人肝癌SMMC－7721细胞受体介导内吞高密度脂蛋白－2的逆向胞饮作用

Retroendocytosis of Endocytic HDL-2 by Human SMMC-7721 Hepatocarcinoma Cells

荧光素异硫氰酸酯标记高密度脂蛋白－２保持天然高密度脂蛋白－２的生物活性。人肝癌ＳＭＭＣ－７７２１细胞与荧光标记无载脂蛋白Ｅ－高密度脂蛋白－２在３７℃培养３ｈ左右，细胞结合与内吞的荧光强度分别为１３．５±０．８和９．２±０．５（±ｓ土）。细胞进一步在３７℃培养２ｈ细胞释放的三氯醋酸沉淀和三氯醋酸可溶性荧光强度分别为５．１±０．４和０．６７±０．１７．４℃培养２ｈ，细胞释放三氯醋酸沉淀荧光强度为０．４１±０．１６。结果提示：①细胞内吞高密度脂蛋白－２没有经过溶酶体分解途径；②细胞释放高密度脂蛋白－２载脂蛋白是一种取决于温度的逆向胞饮机制。

Fluorescein isothiocyanester(FITC)lablled high density lipoprotein-2 keeps the biological activities of native HDL.After human SMMC-7721 hepatocarcinoma cells were incubated with FITCapolipoprotein E-free HDL-2 at 37℃ for 3h, the cellassociated and endocytic fluorescent strength (FS)were 13.5±0.8 and 9.2±0.5(x±s,n=2) respectively. The cell-released trichloroacetic acid (TCA)precipitable FS and TCA-soluble FS were 5.1±0.4and 0.67±0.17 after the cells were incubated further at 37℃ for 2 h. And the cell-released TCA-precipitable FS was 0.41±0.16 at 4℃ for 2h.These results suggest that:①cell-internalized doesn't take lysosomal pathway;②the released of cell-internalized HDL-2-apolipoprotein is a temperature-dependent retroendocytosis.