Harada M, Sakisaka S, Yoshitake M, Kin M, Ohishi M, Shakado S, Mimura Y, Noguchi K, Sata M, Tanikawa K
Second Department of Medicine, Kurume University School of Medicine, Japan.
J Hepatol. 1996 May;24(5):594-603. doi: 10.1016/s0168-8278(96)80146-2.
BACKGROUND/METHODS: The role of vacuolar type H(+)-ATPases (v-ATPases) and pH gradient between the endocytic compartments and cytoplasm in the endocytosis of asialoglycoproteins was morphologically investigated in isolated rat hepatocytes using bafilomycin A1, a specific inhibitor of v-ATPases.
Fluorescent staining by acridine orange showed that bafilomycin A2 inhibited the acidification of the endocytic compartments. Uptake of gold-conjugated asialofetuin was significantly inhibited by bafilomycin A1. However, bafilomycin A1 did not significantly inhibit uptake of a fluid phase marker, horseradish peroxidase. The number of autophagic vacuoles increased after the bafilomycin A1 treatment. However, materials in the autophagic vacuoles were rapidly degraded after the removal of bafilomycin A1.
Results suggest that: (a) v-ATPases are necessary for acidification of the endocytic compartments; (b) the pH gradient between the endocytic compartments and the cytoplasm which is generated by v-ATPases is necessary for the receptor-mediated endocytosis of asialoglycoproteins, and (c) v-ATPases may contribute to the degradation of the materials in autophagic vacuoles.
背景/方法：利用液泡型H(+) -ATP酶（v-ATP酶）的特异性抑制剂巴弗洛霉素A1，在分离的大鼠肝细胞中对v-ATP酶以及内吞小室与细胞质之间的pH梯度在去唾液酸糖蛋白内吞作用中的作用进行了形态学研究。
吖啶橙荧光染色显示巴弗洛霉素A2抑制内吞小室的酸化。巴弗洛霉素A1显著抑制金偶联去唾液酸胎球蛋白的摄取。然而，巴弗洛霉素A1并未显著抑制液相标志物辣根过氧化物酶的摄取。巴弗洛霉素A1处理后自噬泡数量增加。然而，去除巴弗洛霉素A1后，自噬泡内的物质迅速降解。
结果表明：（a）v-ATP酶对于内吞小室的酸化是必需的；（b）由v-ATP酶产生的内吞小室与细胞质之间的pH梯度对于去唾液酸糖蛋白的受体介导内吞作用是必需的，并且（c）v-ATP酶可能有助于自噬泡内物质的降解。
