Bagai S, Sarkar D P
Department of Biochemistry, University of Delhi South Campus, New Delhi, India.
Biochim Biophys Acta. 1993 Oct 10;1152(1):15-25. doi: 10.1016/0005-2736(93)90226-p.
We have assessed the potential of reconstituted Sendai viral envelopes containing only the fusion protein (F-virosomes) as biological carriers for the delivery of drugs and macromolecules. [125I]lysozyme entrapped in F-virosome is used to study its distribution in various organs of Balb/c mouse in vivo as a function of dose and time. F-virosomes injected intravenously are rapidly cleared from circulation. A major percentage (55-60%) of vesicle contents is delivered to liver at 15 min after injection, showing thereby the liver to be the major site for the accumulation of vesicles. Uptake of virosomes by liver is found to reach a near saturation level at a dose of 0.5 mg F-protein associated with virosomes. In competition studies, the inhibitory effect of asialofetuin on the uptake of F-virosomes suggests the involvement of asialoglycoprotein receptor in its recognition by hepatic parenchymal cells. Incorporation of asialoganglioside-GM1 in the F-virosomes enhanced the uptake by about 1.6-fold. The observed specific interaction of hepatic receptor with F-protein containing a terminal galactose moiety is further supported by degalactosylation of F-virosomes with hard-shelled clam exoglycosidase. The uptake of degalactosylated F-virosomes by liver is found to be significantly reduced. The subcellular radioactivity profile in liver cells exhibits a considerable decrease in cytosolic localisation of the degalactosylated F-virosomal contents with a concomitant increase in their accumulation in lysosomal/mitochondrial fraction as compared to the untreated virosomes. Trypsinized and heat-treated F-virosomes also reflect similar subcellular distribution profile as that of degalactosylated virosomes. Moreover, F-virosomes are able to interact and deliver [125I]lysozyme to the HepG2 cells in culture in the presence of a potent inhibitor of endocytotic process. These results indicate the involvement of specific binding of F-proteins with hepatic receptors followed by their fusion with the membrane of liver cells in the delivery of [125I]lysozyme. The findings reported here open up the possibility of using F-virosomes with defined specificity as fusogenic vehicles for efficient delivery of drugs and biologically active macromolecules both in vivo and in vitro.
我们评估了仅含融合蛋白的重组仙台病毒包膜（F-病毒体）作为药物和大分子递送生物载体的潜力。包封于F-病毒体中的[125I]溶菌酶用于研究其在Balb/c小鼠体内各器官中的分布与剂量和时间的关系。静脉注射的F-病毒体迅速从循环中清除。注射后15分钟，大部分（55 - 60%）的囊泡内容物被递送至肝脏，表明肝脏是囊泡积累的主要部位。发现当与病毒体相关的F-蛋白剂量为0.5 mg时，肝脏对病毒体的摄取达到接近饱和水平。在竞争研究中，去唾液酸胎球蛋白对F-病毒体摄取的抑制作用表明去唾液酸糖蛋白受体参与了肝实质细胞对其的识别。在F-病毒体中掺入去唾液酸神经节苷脂-GM1可使摄取增加约1.6倍。用硬壳蛤外切糖苷酶对F-病毒体进行半乳糖基化修饰进一步支持了所观察到的肝受体与含末端半乳糖部分的F-蛋白之间的特异性相互作用。发现肝脏对去半乳糖基化F-病毒体的摄取显著降低。与未处理的病毒体相比，肝细胞中的亚细胞放射性分布显示，去半乳糖基化F-病毒体内容物在胞质中的定位显著减少，同时它们在溶酶体/线粒体部分的积累增加。经胰蛋白酶处理和热处理的F-病毒体也呈现出与去半乳糖基化病毒体相似的亚细胞分布特征。此外，在存在强效内吞过程抑制剂的情况下，F-病毒体能够在培养中与HepG2细胞相互作用并递送[125I]溶菌酶。这些结果表明，在递送[125I]溶菌酶过程中，F-蛋白与肝受体的特异性结合以及随后与肝细胞膜的融合发挥了作用。此处报道的研究结果为将具有明确特异性的F-病毒体用作融合载体在体内和体外高效递送药物和生物活性大分子开辟了可能性。
