Parton R G, Dotti C G, Bacallao R, Kurtz I, Simons K, Prydz K
European Molecular Biology Laboratory, Cell Biology Program, Heidelberg, Federal Republic of Germany.
J Cell Biol. 1991 Apr;113(2):261-74. doi: 10.1083/jcb.113.2.261.
The interaction between late endocytic structures and microtubules in polarized cells was studied using a procedure previously shown to cause microtubule-dependent redistribution of lysosomes in fibroblasts and macrophages (Heuser, J. 1989. J. Cell Biol. 108:855-864). In cultured rat hippocampal neurons, low cytoplasmic pH caused cation-independent mannose-6-phosphate receptor-enriched structures to move out of the cell body and into the processes. In filter grown MDCK cells lowering the cytosolic pH to approximately 6.5 caused late endosomes to move to the base of the cell and this process was shown to be microtubule dependent. Alkalinization caused a shift in distribution towards the apical pole of the cell. The results are consistent with low pH causing the redistribution of late endosomes towards the plus ends of the microtubules. In MDCK cells the microtubules orientated vertically in the cell may play a role in this process. The shape changes that accompanied the redistribution of the late endosomes in MDCK cells were examined by electron microscopy. On low pH treatment fragmentation of the late endosomes was observed whereas after microtubule depolymerization individual late endosomal structures appeared to fuse together. The late endosomes of the MDCK cell appear to be highly pleomorphic and dependent on microtubules for their form and distribution in the cell.
利用先前已证明可导致成纤维细胞和巨噬细胞中溶酶体发生微管依赖性重新分布的方法（Heuser，J. 1989.《细胞生物学杂志》108:855 - 864），研究了极化细胞中晚期内吞结构与微管之间的相互作用。在培养的大鼠海马神经元中，低细胞质pH值导致富含阳离子非依赖性甘露糖-6-磷酸受体的结构移出细胞体并进入突起。在滤膜生长的MDCK细胞中，将胞质pH值降低至约6.5会导致晚期内体移至细胞底部，且该过程被证明是微管依赖性的。碱化导致分布向细胞顶端极转移。结果表明低pH值导致晚期内体向微管正端重新分布。在MDCK细胞中，垂直于细胞排列的微管可能在此过程中起作用。通过电子显微镜检查了MDCK细胞中晚期内体重新分布伴随的形态变化。在低pH处理时观察到晚期内体碎片化，而在微管解聚后，单个晚期内体结构似乎融合在一起。MDCK细胞的晚期内体似乎高度多形，并且其形态和在细胞中的分布依赖于微管。
