Musat A I, Sattler C A, Sattler G L, Pitot H C
Department of Medicine, University of Wisconsin-Madison Medical School 53706.
Hepatology. 1993 Jul;18(1):198-205.
The cell-basement membrane interaction is an important determinant of epithelial cell polarity. Although hepatocytes in situ are polarized, no morphologically identifiable basement membrane is found at their basal surface. However, several studies have demonstrated immunoreactivity to basement membrane proteins in the space of Disse, indicating the existence of an extracellular matrix, albeit of low density. Therefore we hypothesized that the interaction of hepatocytes with this matrix may determine their polarity and asked whether a basement membrane-like substrate could reestablish hepatocyte polarity in vitro. For this purpose, established monolayers of primary rat hepatocytes were cultured overlaid with a basement membrane-like matrix extracted from the Engelbreth-Holm-Swarm mouse tumor, mimicking thus the in situ tissue architecture. The hepatocytes in this culture configuration, unlike hepatocytes in classic cultures, developed distinct membrane domains, as demonstrated by the reformation of gamma-glutamyltranspeptidase, Mg(2+)-ATPase-positive bile canalicular networks and intercellular gap junctions immunolocalized to the lateral membrane with antibodies to connexin 32. The actin cytoskeleton of these cells reorganized into pericanalicular webs, and no accumulation of "stress" filaments was found beneath the membrane facing the medium. Golgi complexes appeared to be preferentially located in mitochondria-poor pericanalicular cytoplasm, indicating the polarized distribution of these organelles. Together, these data indicate that a basement membrane-like substrate present between hepatocytes and nutrient medium restores the polarity of these cells in culture. Extrapolation of these findings to the intact liver suggests that the matrix in Disse's space governs the development of hepatocyte polarity.
细胞与基底膜的相互作用是上皮细胞极性的重要决定因素。尽管原位肝细胞是极性的，但在其基底表面未发现形态上可识别的基底膜。然而，多项研究已证明狄氏间隙中存在对基底膜蛋白的免疫反应性，这表明存在细胞外基质，尽管其密度较低。因此，我们推测肝细胞与这种基质的相互作用可能决定其极性，并询问类似基底膜的底物是否能在体外重建肝细胞极性。为此，将原代大鼠肝细胞的已建立单层培养物覆盖从恩格尔布雷特 - 霍尔姆 - 斯旺小鼠肿瘤中提取的类似基底膜的基质，从而模拟原位组织结构。与经典培养中的肝细胞不同，这种培养配置中的肝细胞形成了明显的膜结构域，γ-谷氨酰转肽酶、Mg(2 +)-ATP酶阳性胆小管网络的重新形成以及用连接蛋白32抗体免疫定位到侧膜的细胞间间隙连接证明了这一点。这些细胞的肌动蛋白细胞骨架重组为胆小管周围的网络，在面向培养基的膜下方未发现“应激”丝的积累。高尔基体复合物似乎优先位于线粒体贫乏的胆小管周围细胞质中，表明这些细胞器的极性分布。总之，这些数据表明肝细胞与营养培养基之间存在的类似基底膜的底物可恢复培养中这些细胞的极性。将这些发现外推到完整肝脏表明，狄氏间隙中的基质控制着肝细胞极性的发展。
