Chao Wei-Ting, Tsai Shu-Huai, Lin Yu-Chun, Lin Wei-Wen, Yang Vivian C
Department of Life Science, Life Science Research Center, Tunghai University, Taichung, Taiwan, ROC.
Biochem Biophys Res Commun. 2005 Jul 8;332(3):743-9. doi: 10.1016/j.bbrc.2005.05.019.
The goal of this study was to investigate the cellular localization and the interaction between caveolin-1 and ABCA1 in cholesterol-loaded aortic endothelial cells after HDL incubation. Immunofluorescence confocal microscopy showed that ABCA1 was found primarily on the cell surface, whereas caveolin-1 was revealed on the cell surface and in the cytoplasm. The HDL appeared to colocalize with ABCA1 and caveolin-1 on the cell surface. No free HDL was revealed in the cytoplasm. The HDL was colocalized neither with early endosome marker (CD71) nor with late endosome marker (LAMP2). The chemical cross-linking and immunoprecipitation analysis revealed that ABCA1 binds directly to both HDL and caveolin-1, whereas HDL does not bind directly to caveolin-1. The studies provide evidence for a direct interaction between ABCA1 and HDL, ABCA1 and caveolin-1, but not HDL and caveolin-1, indicating that ABCA1 may act as a structural platform between HDL and caveolin-1 on the cell surface during cellular cholesterol efflux.
本研究的目的是探讨高密度脂蛋白（HDL）孵育后，胆固醇负荷的主动脉内皮细胞中窖蛋白-1（caveolin-1）与ATP结合盒转运体A1（ABCA1）的细胞定位及相互作用。免疫荧光共聚焦显微镜显示，ABCA1主要位于细胞表面，而窖蛋白-1在细胞表面和细胞质中均有表达。HDL似乎与细胞表面的ABCA1和窖蛋白-1共定位。细胞质中未发现游离的HDL。HDL既不与早期内体标记物（CD71）共定位，也不与晚期内体标记物（LAMP2）共定位。化学交联和免疫沉淀分析表明，ABCA1直接与HDL和窖蛋白-1结合，而HDL不直接与窖蛋白-1结合。这些研究为ABCA1与HDL、ABCA1与窖蛋白-1之间存在直接相互作用提供了证据，但HDL与窖蛋白-1之间不存在直接相互作用，这表明在细胞胆固醇流出过程中，ABCA1可能在细胞表面的HDL与窖蛋白-1之间充当结构平台。
