Korkotian E, Schwarz A, Pelled D, Schwarzmann G, Segal M, Futerman A H
Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100, Israel.
J Biol Chem. 1999 Jul 30;274(31):21673-8. doi: 10.1074/jbc.274.31.21673.
Gaucher disease is a glycosphingolipid storage disease caused by defects in the activity of the lysosomal hydrolase, glucocerebrosidase (GlcCerase), resulting in accumulation of glucocerebroside (glucosylceramide, GlcCer) in lysosomes. The acute neuronopathic type of the disease is characterized by severe loss of neurons in the central nervous system, suggesting that a neurotoxic agent might be responsible for cellular disruption and neuronal death. We now demonstrate that upon incubation with a chemical inhibitor of GlcCerase, conduritol-B-epoxide (CBE), cultured hippocampal neurons accumulate GlcCer. Surprisingly, increased levels of tubular endoplasmic reticulum elements, an increase in Ca(2+) response to glutamate, and a large increase in Ca(2+) release from the endoplasmic reticulum in response to caffeine were detected in these cells. There was a direct relationship between these effects and GlcCer accumulation since co-incubation with CBE and an inhibitor of glycosphingolipid synthesis, fumonisin B(1), completely antagonized the effects of CBE. Similar effects on endoplasmic reticulum morphology and Ca(2+) stores were observed upon incubation with a short-acyl chain, nonhydrolyzable analogue of GlcCer, C(8)-glucosylthioceramide. Finally, neurons with elevated GlcCer levels were much more sensitive to the neurotoxic effects of high concentrations of glutamate than control cells; moreover, this enhanced toxicity was blocked by pre-incubation with ryanodine, suggesting that Ca(2+) release from ryanodine-sensitive intracellular stores can induce neuronal cell death, at least in neurons with elevated GlcCer levels. These results may provide a molecular mechanism to explain neuronal dysfunction and cell death in neuronopathic forms of Gaucher disease.
戈谢病是一种糖鞘脂贮积病，由溶酶体水解酶葡萄糖脑苷脂酶（GlcCerase）活性缺陷引起，导致葡萄糖脑苷脂（葡糖神经酰胺，GlcCer）在溶酶体中蓄积。该疾病的急性神经病变型的特征是中枢神经系统中神经元严重缺失，这表明一种神经毒性剂可能是细胞破坏和神经元死亡的原因。我们现在证明，在用葡萄糖脑苷脂酶的化学抑制剂环多醇 - B - 环氧化物（CBE）孵育后，培养的海马神经元会蓄积GlcCer。令人惊讶的是，在这些细胞中检测到管状内质网元件水平增加、对谷氨酸的Ca(2 +)反应增加以及对咖啡因的反应中内质网Ca(2 +)释放大幅增加。这些效应与GlcCer蓄积之间存在直接关系，因为与CBE和糖鞘脂合成抑制剂伏马菌素B(1)共同孵育可完全拮抗CBE的效应。在用短酰基链、不可水解的GlcCer类似物C(8)-葡糖硫代神经酰胺孵育后，观察到对内质网形态和Ca(2 +)储存有类似的影响。最后，GlcCer水平升高的神经元对高浓度谷氨酸的神经毒性作用比对照细胞敏感得多；此外，这种增强的毒性可被用ryanodine预孵育阻断，这表明从ryanodine敏感的细胞内储存中释放Ca(2 +)可诱导神经元细胞死亡，至少在GlcCer水平升高的神经元中如此。这些结果可能提供一种分子机制来解释戈谢病神经病变型中的神经元功能障碍和细胞死亡。
