Pipalia Nina H, Hao Mingming, Mukherjee Sushmita, Maxfield Frederick R
Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021, USA.
Traffic. 2007 Feb;8(2):130-41. doi: 10.1111/j.1600-0854.2006.00513.x. Epub 2006 Dec 7.
We studied the trafficking of sterols, lipids and proteins in Niemann-Pick type C (NPC) cells. The NPC is an inherited disorder involving the accumulation of sterol and lipids in modified late-endosome/lysosome-like storage organelles. Most sterol accumulation studies in NPC cells have been carried out using low-density lipoprotein (LDL) as the sterol source, and it has been shown that sterol efflux from late endosomes is impaired in NPC cells. In this study, we used a fluorescent sterol analog, dehydroergosterol, which can be quickly and efficiently delivered to the plasma membrane. Thus, we were able to study the trafficking kinetics of the non-LDL-derived sterol pool, and we found that dehydroergosterol accumulates in the storage organelles over the course of several hours in NPC cells. We also found that dialkylindocarbocyanine lipid-mimetic analogs that recycle efficiently from early endosomes in wild-type cells are targeted to late endosomal organelles in NPC cells, and transferrin receptors recycle slowly and inefficiently in NPC cells. These data are consistent with multiple trafficking defects in both early and late endosomes in NPC cells.
我们研究了尼曼-匹克C型（NPC）细胞中固醇、脂质和蛋白质的运输情况。NPC是一种遗传性疾病，涉及固醇和脂质在经过修饰的晚期内体/溶酶体样储存细胞器中的积累。大多数针对NPC细胞中固醇积累的研究都是使用低密度脂蛋白（LDL）作为固醇来源进行的，并且已经表明NPC细胞中晚期内体的固醇流出受损。在本研究中，我们使用了一种荧光固醇类似物——脱氢麦角固醇，它能够快速且高效地被转运到质膜。因此，我们能够研究非LDL来源的固醇池的运输动力学，并且我们发现脱氢麦角固醇在NPC细胞中会在数小时内积累在储存细胞器中。我们还发现，在野生型细胞中能从早期内体有效循环的二烷基吲哚碳菁脂质模拟类似物在NPC细胞中靶向晚期内体细胞器，并且转铁蛋白受体在NPC细胞中的循环缓慢且效率低下。这些数据与NPC细胞早期和晚期内体中存在多种运输缺陷一致。
