Phosphatidylinositol 3-kinase is not required for recycling of mannose 6-phosphate receptors from late endosomes to the trans-Golgi network.
Phosphatidylinositol 3-kinase is not required for recycling of mannose 6-phosphate receptors from late endosomes to the trans-Golgi network.
复制标题
将甘露糖 6-磷酸受体从晚期内涵体再循环到跨高尔基体网络不需要磷脂酰肌醇 3-激酶。
DOI：
10.1091/mbc.8.4.577
复制
发表时间：
1997
影响因子：
3.3
通讯作者：
Pfeffer,SR
中科院分区：
文献类型：
--
作者：
Nakajima,Y;Pfeffer,SR
甘露糖6-磷酸受体携带新合成的溶酶体水解酶从trans-Golgi网络到内体，然后返回到trans-Golgi网络进行另一轮酶递送。Wortmannin是磷脂酰肌醇3-激酶的抑制剂，干扰新合成的溶酶体酶向溶酶体的递送。我们使用了两个独立的甘露糖6-磷酸受体运输的测定，以确定被渥曼青霉素阻断的精确步骤。使用一种检测方法，监测再唾液酸化的细胞表面300 kDa甘露糖6-磷酸受体，我们发现，受体的内吞作用和运输到trans-Golgi网络不抑制2 μ M渥曼青霉素。此外，该浓度的药物对甘露糖6-磷酸受体从晚期内体转运至trans-Golgi网络没有影响，所述转运使用在细胞提取物中重建该转运过程的系统。在相同条件下，渥曼青霉素显著抑制成熟组织蛋白酶D的生成。此外，结构无关的磷脂酰肌醇3-激酶抑制剂，LY 294002，也没有影响时，在体外内体trans-Golgi网络运输反应。这些实验表明，溶酶体酶靶向的中断最有可能是由于这些受体从反式高尔基体网络输出所需的渥曼青霉素敏感过程，这与磷脂酰肌醇3-激酶在等效转运过程中的既定作用一致。在酿酒酵母中。
Mannose 6-phosphate receptors carry newly synthesized lysosomal hydrolases from the trans-Golgi network to endosomes, then return to the trans-Golgi network for another round of enzyme delivery. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, interferes with the delivery of newly synthesized lysosomal enzymes to lysosomes. We used two independent assays of mannose 6-phosphate receptor trafficking to determine the precise step that is blocked by wortmannin. Using an assay that monitors resialylation of desialylated cell surface 300-kDa mannose 6-phosphate receptors, we found that receptor endocytosis and transport to the trans-Golgi network were not inhibited by 2 microM wortmannin. In addition, this concentration of drug had no effect on the transport of the mannose 6-phosphate receptor from late endosomes to the trans-Golgi network using a system that reconstitutes this transport process in cell extracts. Under the same conditions, wortmannin significantly inhibited the generation of mature cathepsin D. In addition, the structurally unrelated phosphatidylinositol 3-kinase inhibitor, LY294002, was also without effect when added to in vitro endosome-trans-Golgi network transport reactions. These experiments demonstrate that the interruption in lysosomal enzyme targeting is most likely due to a wortmannin-sensitive process required for the export of these receptors from the trans-Golgi network, consistent with the established role of phosphatidylinositol 3-kinase in the equivalent transport process in Saccharomyces cerevisiae.