rAAV2/1-SR-BI-IRES-EGFP转染HepG2肝细胞对^(125)I-HDL摄取的调节

Regulation of rAAV2/1-SR-BI-IRES-EGFP Transfection on Uptake of HDL in HepG2 Hepatoma Cells

【目的】探讨B族I型清道夫受体(SR-BI)过表达对高密度脂蛋白(HDL)摄取的调节,为SR-B1在胆固醇逆转运(RCT)及动脉粥样硬化(AS)中的研究提供新思路。【方法】用含SR-BI基因的重组腺相关病毒r AAV2/1-SR-BI-IRESEGFP杂合载体转染人Hep G2肝细胞株,Realtime RT-PCR和Western Blot分别检测转染后SR-BI m RNA和蛋白的表达。125I-HDL同位素标记观察转染对HDL结合的影响。激光共聚焦显微镜观察转染后SR-BI细胞分布及转移情况。【结果】与未转染组及对照病毒r AAV2/1-IRES-EGFP转染组相比,重组病毒r AAV2/1-SR-BI-IRES-EGFP转染组SR-BI m RNA水平和蛋白表达显著增加,差别均有统计学意义(P均<0.01),且可以引起125I标记的HDL与Hep G2肝细胞的结合增加1.28倍和1.40倍,差别均有统计学意义(P均<0.01)。在无血清状态下,我们用激光共聚焦显微镜观察发现SR-BI同时位于细胞膜和细胞浆,HDL可以促进SR-BI从细胞浆到细胞表面的转移。【结论】SR-BI过表达可以增加Hep G2肝细胞HDL的摄取且摄取可能主要发生在细胞膜上,SR-BI参与了RCT的过程。

[Objective] The aim of this study was to investigate the effect of scavenger receptor class B type I （SR-BI） overexpression on the uptake of high density lipoprotein （HDL） and provide a novel thought to research the role of SR-B1 in reverse cholesterol transport （RCT） and atherosclerosis （AS）. [Methods] We adopted recombinant vectors rAAV2/1-SR-BI-IRES- EGFPtotransfect human HepG2 hepatoma cells. Then, the expressions of SR-BI mRNA and protein were detected by Real-time RT- PCR analysis and Western blot analysis after transfection. HDL was labeled by radioiodination of the protein component using I and radioactivity were measured after transfection. [ Results] Compared with the control and rAAV2/1-IRES-EGFP transfection group, the expressions of SR-BI mRNA and protein were significantly increased as well as the increasing uptake of 125I-HDL （by !.28 and 1.40 times, respectively）after rAAV2/1-SR-BI-IRES-EGFP transfection （P 〈 0.05）. RAAV2/1-SR-BI-IRES-EGFP was found distributed both in the cytoplasm and cell membrane in serum-starved cells. However, HDL resulted in a marked redistribution of the bulk of rAAV2/1-SR-BI-IRES-EGFP to the cell surface. [Conclusion] SR-B1 overexpression increases the uptake of HDL in HepG2 hepatoma cells, which might occur in the cell surface. Thus, the overexpression of SR-BI gene could increase the RCT pathway by promoting cholesterol ester uptake from plasma HDL.