Pelled D, Shogomori H, Futerman A H
Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel.
J Inherit Metab Dis. 2000 Mar;23(2):175-84. doi: 10.1023/a:1005622001239.
We have recently demonstrated that incubation of cultured rat hippocampal neurons with conduritol beta-epoxide (CBE), an inhibitor of glucocerebrosidase, the enzyme defective in Gaucher disease, results in changes in intracellular morphology and in functional calcium stores. Changes in levels of functional calcium stores are directly related to neuronal cell death. We now show that neurons incubated with either CBE or a non-hydrolysable analogue of GlcCer (glucosylthioceramide), are more sensitive to the toxic effects of high concentrations of glutamate and of a variety of metabolic inhibitors. A linear relationship exists between level of accumulation of GlcCer and the extent of neuronal cell death. The deleterious effects of elevated GlcCer levels can be completely reversed by addition of human glucocerebrosidase (imiglucerase) to the culture medium. Imiglucerase is internalized to lysosomes, where it presumably degrades excess GlcCer. This suggests that the limited success of enzyme replacement therapy in neuronopathic forms of Gaucher disease is not due to lack of efficacy of glucocerebroside in degrading GlcCer in neurons of the central nervous system, and adds impetus to attempts to develop ways to efficiently deliver glucocerebrosidase to the brains of neurologically compromised Gaucher disease patients.
我们最近证明，用葡萄糖脑苷脂酶（葡糖脑苷脂酶）的抑制剂——伴刀豆球蛋白β - 环氧化物（CBE）培养大鼠海马神经元，葡糖脑苷脂酶是戈谢病中存在缺陷的酶，这会导致细胞内形态和功能性钙储存的变化。功能性钙储存水平的变化与神经元细胞死亡直接相关。我们现在表明，用CBE或GlcCer（葡糖基硫代神经酰胺）的不可水解类似物培养的神经元，对高浓度谷氨酸和多种代谢抑制剂的毒性作用更敏感。GlcCer的积累水平与神经元细胞死亡程度之间存在线性关系。通过向培养基中添加人葡萄糖脑苷脂酶（伊米苷酶），可以完全逆转升高的GlcCer水平的有害影响。伊米苷酶被内化到溶酶体中，在那里它可能降解过量的GlcCer。这表明，在戈谢病的神经元病变形式中，酶替代疗法取得有限成功并非由于葡萄糖脑苷脂在中枢神经系统神经元中降解GlcCer的功效不足，这也为尝试开发有效将葡萄糖脑苷脂酶递送至神经功能受损的戈谢病患者大脑的方法增添了动力。
