Receptor-mediated transcytosis of IgA in MDCK cells is via apical recycling endosomes.
Receptor-mediated transcytosis of IgA in MDCK cells is via apical recycling endosomes.
复制标题
MDCK细胞中IgA的受体介导的转介症是通过根尖回收的内体。
DOI：
10.1083/jcb.125.1.67
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发表时间：
1994-04
影响因子：
7.8
通讯作者：
Mostov, K E
中科院分区：
文献类型：
--
作者：
Apodaca, G;Katz, L A;Mostov, K E
传统上，认为多聚免疫球蛋白受体及其配体伊加从基底外侧早期内体分选到直接与顶端质膜融合的胞吞囊泡中。相比之下，我们发现在MDCK细胞中，伊加从基底外侧内体递送至顶端内体，然后仅递送至顶端细胞表面。当从MDCK细胞的基底外侧表面内化时，发现伊加在顶端质膜下积聚在一个隔室中，该隔室可接近两个顶端添加的膜标记物：抗分泌组分Fab片段和从细胞的生物素化顶端极内化的抗生物素蛋白。这种积累发生在顶端胰蛋白酶的存在下，其防止配体从顶端细胞表面内化。使用修改的二氨基联苯胺密度漂移试验，我们估计，约80%的基底外侧内化伊加驻留在顶端内体室。此外，大约50%的基底外侧内化的转铁蛋白（一种基底外侧再循环蛋白）可以进入该顶端内体区室，并有效地再循环回基底外侧表面。微管是组织顶端内体区室所必需的，它分散在诺考达唑处理的细胞中。此外，该隔室在很大程度上是不可接近的流体相标记物添加到细胞的两极，因此似乎类似于非极化细胞中描述的再循环内体。我们提出了一个模型，其中转胞吞作用不是使用独特的转胞吞囊泡的专门途径，而是结合了非转胞吞分子使用的部分途径。
Classically, the polymeric immunoglobulin receptor and its ligand, IgA, are thought to be sorted from basolateral early endosomes into transcytotic vesicles that directly fuse with the apical plasma membrane. In contrast, we have found that in MDCK cells IgA is delivered from basolateral endosomes to apical endosomes and only then to the apical cell surface. When internalized from the basolateral surface of MDCK cells IgA is found to accumulate under the apical plasma membrane in a compartment that is accessible to two apically added membrane markers: anti-secretory component Fab fragments, and avidin internalized from the biotinylated apical pole of the cell. This accumulation occurs in the presence of apical trypsin, which prevents internalization of the ligand from the apical cell surface. Using a modification of the diaminobenzidine density-shift assay, we estimate that approximately 80% of basolaterally internalized IgA resides in the apical endosomal compartment. In addition, approximately 50% of basolaterally internalized transferrin, a basolateral recycling protein, has access to this apical endosomal compartment and is efficiently recycled back to the basolateral surface. Microtubules are required for the organization of the apical endosomal compartment and it is dispersed in nocodazole-treated cells. Moreover, this compartment is largely inaccessible to fluid-phase markers added to either pole of the cell, and therefore seems analogous to the recycling endosome described in nonpolarized cells. We propose a model in which transcytosis is not a specialized pathway that uses unique transcytotic vesicles, but rather combines portions of pathways used by non- transcytosing molecules.