Jackman M R, Shurety W, Ellis J A, Luzio J P
Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, UK.
J Cell Sci. 1994 Sep;107 ( Pt 9):2547-56. doi: 10.1242/jcs.107.9.2547.
Apical and basolateral endocytic pathways in polarised Caco-2 cells were investigated by following the uptake, recycling and transcytosis of the galactose-binding protein toxin ricin, as a membrane marker. Differences in the extent and kinetics of lectin uptake, recycling and transcytosis were observed at the apical and basolateral domains and altered with the age of the cell monolayer. Treatment of polarised Caco-2 cells with cytochalasin D showed a domain-specific, concentration-dependent inhibition of apical endocytosis of ricin. Inhibition of apical endocytosis by cytochalasin D was not due to a gross change in brush border morphology, although actin stress fibres within the cell body were disrupted. It is not clear whether inhibition of apical endocytosis in polarized epithelial cells by cytochalasin D is caused simply by disruption of a mechanochemical motor involving microvillar actin filaments. The cytochalasin D effect was also observed when measuring uptake of folate, suggesting apical domain-specific inhibition of caveolar, as well as clathrin-mediated, endocytic routes.
通过追踪半乳糖结合蛋白毒素蓖麻毒素（作为一种膜标记物）的摄取、循环利用和转胞吞作用，研究了极化的Caco-2细胞中的顶端和基底外侧内吞途径。在顶端和基底外侧结构域观察到凝集素摄取、循环利用和转胞吞作用在程度和动力学上的差异，并且这些差异随细胞单层的年龄而改变。用细胞松弛素D处理极化的Caco-2细胞显示出对蓖麻毒素顶端内吞作用的结构域特异性、浓度依赖性抑制。细胞松弛素D对顶端内吞作用的抑制不是由于刷状缘形态的总体变化，尽管细胞体内的肌动蛋白应力纤维被破坏。尚不清楚细胞松弛素D对极化上皮细胞顶端内吞作用的抑制是否仅仅是由涉及微绒毛肌动蛋白丝的机械化学马达的破坏引起的。在测量叶酸摄取时也观察到了细胞松弛素D的作用，这表明对小窝介导的以及网格蛋白介导的内吞途径存在顶端结构域特异性抑制。
