Low S H, Wong S H, Tang B L, Hong W
Membrane Biology Laboratory, National University of Singapore, Kent Ridge Crescent.
Mol Membr Biol. 1994 Jan-Mar;11(1):45-54. doi: 10.3109/09687689409161029.
The extracellular matrix protein fibronectin was found to be secreted by three polarized epithelial cell lines Madin-Darby canine kidney (MDCK), Caco-2 and LLC-PK1. About 54 and 46% of fibronectin was secreted from the apical and basolateral cell surfaces, respectively, in MDCK cells. In Caco-2 and LLC-PK1 cells, the majority (about 92-93%) of fibronectin secretion occurs from the basolateral cell surface, with the remaining 7-8% from the apical surface. In all three cell types, NH4Cl was found to inhibit basolateral secretion (resulting in enhanced apical secretion), while total fibronectin secretion was not significantly affected (although a delay in secretion was observed). Nocodazole reduced total fibronectin secretion to about 70% of control levels in MDCK and Caco-2 cells, with significant inhibition on secretion from both surfaces. In contrast, total fibronectin secretion was enhanced by nocodazole in LLC-PK1 cells. Furthermore, the majority of fibronectin secretion was redirected to the apical cell surface in LLC-PK1 cells. These observations demonstrate that the nature as well as the extent of the effects of NH4-Cl and nocodazole on polarized fibronectin secretion varies amongst different epithelial cell types.
细胞外基质蛋白纤连蛋白被发现由三种极化上皮细胞系——犬肾细胞系（MDCK）、人结肠腺癌细胞系（Caco - 2）和猪肾近曲小管上皮细胞系（LLC - PK1）分泌。在MDCK细胞中，分别约有54%和46%的纤连蛋白从细胞顶端和基底外侧表面分泌。在Caco - 2细胞和LLC - PK1细胞中，大部分（约92% - 93%）纤连蛋白从基底外侧细胞表面分泌，其余7% - 8%从顶端表面分泌。在所有这三种细胞类型中，发现氯化铵可抑制基底外侧分泌（导致顶端分泌增强），而纤连蛋白的总分泌量未受到显著影响（尽管观察到分泌延迟）。诺考达唑使MDCK细胞和Caco - 2细胞中纤连蛋白的总分泌量降至对照水平的约70%，对两个表面的分泌均有显著抑制作用。相比之下，诺考达唑使LLC - PK1细胞中纤连蛋白的总分泌量增加。此外，在LLC - PK1细胞中，大部分纤连蛋白分泌被重新导向细胞顶端表面。这些观察结果表明，氯化铵和诺考达唑对极化纤连蛋白分泌的影响性质以及程度在不同上皮细胞类型中有所不同。
