Targeting of aminopeptidase N to bile canaliculi correlates with secretory activities of the developing canalicular domain
Targeting of aminopeptidase N to bile canaliculi correlates with secretory activities of the developing canalicular domain
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DOI：
10.1002/hep.510300302
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发表时间：
1999-09-01
期刊：
影响因子：
13.5
通讯作者：
Lin, CH
中科院分区：
文献类型：
--
作者：
Lian, WN;Tsai, JW;Lin, CH
我们以人肝癌细胞系为体外模型，研究了肝胆管的发育。分化良好的肝癌细胞培养72小时后，可在细胞-细胞接触部位形成典型的椭圆形结构，内含紧密连接和各种膜蛋白标记物，类似于体内发现的BC。完整的细胞骨架对这种分化过程是必不可少的。在不同来源的细胞共同培养的实验中，BC只在肝细胞之间形成，并且优先在分化良好的细胞中形成。低分化肝癌细胞之间不会形成BC，但可以通过与分化良好的细胞相互作用而被诱导分化为小管。在BC的形态发生过程中，完整的小管膜蛋白在发育中的BC逐渐递送和积累。其中，靶向氨基肽酶N(APN)似乎与某些分泌功能的激活有关。具体地说，只有APN阳性的BC支持二醋酸荧光素(FDA)和70kd的葡聚糖的分泌，但与辣根过氧化物酶(HRP)的分泌无关，另一方面，靶向另一种BC蛋白二肽基肽酶IV(DPPIV)与所研究的任何分泌活性无关。此外，抑制APN的酶活性可以扰乱小管的分化，而不影响细胞的增殖。我们的结果提示，靶向APN蛋白可能反映甚至在小管结构的发育和功能成熟中发挥重要作用。
We have used human hepatoma cell lines as an in vitro model to study the development of hepatic bile canaliculi (BC). Well-differentiated hepatoma cells cultured for 72 hours could develop characteristic spheroid structures at sites of cell-cell contact that contained tight junctions and various membrane protein markers, resembling BC found in vivo. Intact cytoskeleton was essential for this differentiation process. In the coculture experiments in which cells of different origins were populated together, BC only formed between hepatic cells and preferentially among well-differentiated cells. Poorly differentiated hepatoma cells never formed BC among themselves, but could be induced to undergo canalicular differentiation by interacting with well-differentiated cells. During BC morphogenesis, integral canalicular membrane proteins were gradually delivered and accumulated at the developing BC. Among them, targeting of aminopeptidase N (APN) seemed to correlate with activation of certain secretory functions. Specifically, only APN-positive BC supported excretion of fluorescein diacetate (FDA) and 70-kd dextran, but had no relationship with secretion of horseradish peroxidase (HRP), Targeting of another BC protein, dipeptidyl peptidase IV (DPPIV), on the other hand, bore no association with any secretory activity examined. In addition, inhibition of enzymatic activity of APN could perturb canalicular differentiation without affecting cell proliferation. Our results suggest that targeting of APN proteins may reflect or even play an important role in the development and functional maturation of the canalicular structures.