Cholesterol Modulates -Secretase Cleavage of Amyloid Precursor Protein (*)
Cholesterol Modulates -Secretase Cleavage of Amyloid Precursor Protein (*)
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DOI：
10.1074/jbc.271.8.4436
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发表时间：
1996-02
期刊：
影响因子：
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通讯作者：
S. Bodovitz;W. Klein
中科院分区：
文献类型：
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作者：
S. Bodovitz;W. Klein
淀粉样前体蛋白（APP）和胆固醇代谢与阿尔茨海默病有遗传联系，后者通过载脂蛋白E，一种脂质和胆固醇转运蛋白。我们已经研究了这一假设，即APP的加工被高胆固醇破坏，这是已知的调节几个跨膜蛋白的活性。在本研究中，将用甲基-β-环糊精或乙醇增溶的胆固醇加入到APP 751稳定转染的HEK 293细胞的培养基中。从稳定转染的HEK 293细胞的裂解物和条件培养基中沉淀放射性标记的APP和APP（α-分泌酶裂解后的可溶性N-末端衍生物）;通过SDS-聚丙烯酰胺凝胶电泳分离后，通过定量光密度测定法测定相对水平。结果表明，甲基-β-环糊精增溶胆固醇后，APP水平显著降低，低剂量乙醇增溶胆固醇后APP水平显著降低，APP全蛋白水平保持不变或升高。APP产生的大量减少不是由于分泌的非特异性抑制，因为几种分泌蛋白的水平增加。胆固醇阻碍膜流动性，可能通过阻碍底物与其蛋白酶的相互作用来降低APP的产生。如果APP是营养功能，如其他研究所建议的那样，目前的结论表明，阿尔茨海默病中细胞胆固醇水平的变化可能会通过减少APP的产生而导致神经元变性。
Amyloid precursor protein (APP) and cholesterol metabolism are genetically linked to Alzheimer's disease, the latter through apolipoprotein E, a lipid and cholesterol transport protein. We have examined the hypothesis that the processing of APP is disrupted by elevated cholesterol, which is known to modulate the activity of several transmembrane proteins. In the current study, cholesterol, solubilized by methyl-β-cyclodextrin or ethanol, was added to the culture media of APP 751 stably transfected HEK 293 cells. Radiolabeled APP and APP (the soluble N-terminal derivative following α-secretase cleavage) were precipitated from lysates and conditioned media of stably transfected HEK 293 cells; the relative levels were determined by quantitative densitometry following separation by SDS-polyacrylamide gel electrophoresis. The data show that cholesterol, solubilized by methyl-β-cyclodextrin, greatly reduced the levels of APP. Low doses of ethanol-solubilized cholesterol similarly caused a dramatic reduction of APP. By contrast, levels of APP holoprotein remained the same or increased. The large decrease seen in APP production was not due to nonspecific inhibition of secretion because several secreted proteins increased in level. Cholesterol, which impedes membrane fluidity, may lower APP production by impeding the interaction of the substrate with its protease(s). If APP were to function trophically, as suggested by other studies, the current conclusion suggests that changes in cellular cholesterol levels in Alzheimer's disease could contribute to neuronal degeneration by decreasing the production of APP.