Endocytosis of beta-cyclodextrins is responsible for cholesterol reduction in Niemann-Pick type C mutant cells
Endocytosis of beta-cyclodextrins is responsible for cholesterol reduction in Niemann-Pick type C mutant cells
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DOI：
10.1073/pnas.0914309107
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发表时间：
2010-03-23
影响因子：
11.1
通讯作者：
Maxfield, Frederick R.
中科院分区：
文献类型：
--
作者：
Rosenbaum, Anton I.;Zhang, Guangtao;Maxfield, Frederick R.
C型尼曼-匹克病（NPC）是一种溶酶体胆固醇沉积症，导致未酯化胆固醇在溶酶体胆固醇沉积细胞器中蓄积。最近的研究表明，npc 1（-/-）小鼠注射羟丙基-β-环糊精对治疗这种疾病部分有效。使用培养的成纤维细胞，我们已经调查了负责减少胆固醇积累的细胞机制。我们表明，降低胆固醇积累水平保持了几天后，从培养基中去除环糊精。这表明，内吞的环糊精可以减少胆固醇的储存，从内吞细胞器内部的作用，而不是通过从质膜上清除胆固醇。为了进一步测试这一点，我们将NPC 1和NPC 2突变体细胞与胆固醇负载的环糊精一起孵育1小时，然后在含血清培养基中追逐。虽然处理后的细胞的胆固醇含量增加1小时孵育后，胆固醇水平的存储细胞器后来显着降低。我们共价偶联环糊精荧光葡聚糖聚合物。这些环糊精-葡聚糖缀合物被递送到富含胆固醇的溶酶体储存细胞器，并且有效地减少胆固醇积累。我们证明甲基-β-环糊精在降低NPC突变成纤维细胞中胆固醇和双（单酰基甘油）磷酸盐积累方面比羟丙基-β-环糊精更有效。用环糊精对细胞进行短暂处理会导致通过酰基CoA：胆固醇酰基转移酶进行的胆固醇酯化增加，表明胆固醇向内质网的递送增加。这些发现表明，环糊精介导的增强胆固醇从内吞系统的转运可以减少胆固醇在NPC 1或NPC 2缺陷的细胞中的积累。
Niemann-Pick type C disease (NPC) is a lysosomal storage disorder causing accumulation of unesterified cholesterol in lysosomal storage organelles. Recent studies have shown that hydroxypropyl-beta-cyclodextrin injections in npc1(-/-) mice are partially effective in treating this disease. Using cultured fibroblasts, we have investigated the cellular mechanisms responsible for reduction of cholesterol accumulation. We show that decreased levels of cholesterol accumulation are maintained for several days after removal of cyclodextrin from the culture medium. This suggests that endocytosed cyclodextrin can reduce the cholesterol storage by acting from inside endocytic organelles rather than by removing cholesterol from the plasma membrane. To test this further, we incubated both NPC1 and NPC2 mutant cells with cholesterol-loaded cyclodextrin for 1 h, followed by chase in serum-containing medium. Although the cholesterol content of the treated cells increased after the 1-h incubation, the cholesterol levels in the storage organelles were later reduced significantly. We covalently coupled cyclodextrin to fluorescent dextran polymers. These cyclodextrin-dextran conjugates were delivered to cholesterol-enriched lysosomal storage organelles and were effective at reducing the cholesterol accumulation. We demonstrate that methyl-beta-cyclodextrin is more potent than hydroxypropyl-beta-cyclodextrin in reducing both cholesterol and bis(monoacylglycerol) phosphate accumulation in NPC mutant fibroblasts. Brief treatment of cells with cyclodextrins causes an increase in cholesterol esterification by acyl CoA:cholesterol acyl transferase, indicating increased cholesterol delivery to the endoplasmic reticulum. These findings suggest that cyclodextrin-mediated enhanced cholesterol transport from the endocytic system can reduce cholesterol accumulation in cells with defects in either NPC1 or NPC2.