Rescan P Y, Loréal O, Hassell J R, Yamada Y, Guillouzo A, Clément B
Unité de Recherches Hépatologiques, INSERM U49, Hôpital Pontchaillou, Rennes, France.
Am J Pathol. 1993 Jan;142(1):199-208.
Basement membranes contain three major components (ie collagen IV, laminin, and the heparan sulfate proteoglycan termed perlecan). Although the distribution and origin of both collagen IV and laminin have been well documented in the liver, perlecan has been poorly investigated, so far. We have studied the distribution and cellular origin of perlecan in rat livers in various conditions as well as in hepatocyte primary culture. By immunolocalization in both adult and 18-day-old fetal liver, perlecan was found in portal spaces, around central veins, and throughout the lobule. Immunoelectron microscopy revealed its presence at the level of basement membranes surrounding bile ducts and blood vessels, and in the space of Disse discontinuously interacting with hepatocyte microvilli. Precursors of perlecan were detected in the rough endoplasmic reticulum of bile duct cells and both vascular and sinusoidal endothelial cells. Both hepatocytes and Ito cells were negative. Northern-blot analysis confirmed the lack of appreciable expression of perlecan in hepatocytes isolated from either fetal or adult livers. In 18-month-diethylnitrosamine-treated rat liver, perlecan was abundant in neoplastic nodules. Electron microscopic investigation revealed an almost continuous layer of perlecan in the space of Disse and intracellular staining in sinusoidal endothelial cells, only. Perlecan mRNAs were detectable in malignant nodules, and absent in hepatocytes from nontumorous areas. Hepatocytes expressed high levels of perlecan mRNAs only when put in culture. This expression was reduced in conditions that allow improvement of hepatocyte survival and function (ie addition of corticoids, dimethylsulfoxide or nicotinamide to the medium, or in coculture with liver epithelial cells from biliary origin). Immunolocalization by light and electron microscopy showed that deposition of the proteoglycan occurred in coculture, in basement membranelike structures located around hepatocyte cords. In vitro attachment assay of hepatocytes on purified perlecan substrate indicated that these cells may interact with the proteoglycan through integrins which belong to the beta 1 family. These data suggest that deposition of perlecan in the space of Disse requires cellular cooperation. This article on perlecan, the third major component of hepatic basement membranes, shows a unique cellular origin in the liver and, as found for both collagen IV and laminin, an expression in adult hepatocytes when place in culture.
基底膜包含三种主要成分（即IV型胶原、层粘连蛋白和被称为基底膜聚糖的硫酸乙酰肝素蛋白聚糖）。尽管IV型胶原和层粘连蛋白在肝脏中的分布及来源已有充分记载，但迄今为止，对基底膜聚糖的研究还很少。我们研究了基底膜聚糖在不同条件下大鼠肝脏以及肝细胞原代培养中的分布和细胞来源。通过对成年和18日龄胎肝进行免疫定位，发现基底膜聚糖存在于门管区、中央静脉周围以及整个肝小叶。免疫电子显微镜显示其存在于胆管和血管周围的基底膜水平，以及狄氏间隙中，与肝细胞微绒毛间断性相互作用。在胆管细胞、血管内皮细胞和窦状内皮细胞的粗面内质网中检测到基底膜聚糖的前体。肝细胞和贮脂细胞均为阴性。Northern印迹分析证实，从胎肝或成年肝脏分离的肝细胞中基底膜聚糖没有明显表达。在18月龄经二乙基亚硝胺处理的大鼠肝脏中，基底膜聚糖在肿瘤结节中大量存在。电子显微镜研究显示，仅在狄氏间隙中有几乎连续的基底膜聚糖层，且仅在窦状内皮细胞中有细胞内染色。在恶性结节中可检测到基底膜聚糖mRNA，而在非肿瘤区域的肝细胞中则不存在。肝细胞仅在培养时才表达高水平的基底膜聚糖mRNA。当在培养基中添加皮质激素、二甲基亚砜或烟酰胺，或与胆管来源的肝上皮细胞共培养时，这种表达会降低，而这些条件有利于肝细胞存活和功能改善。光镜和电镜免疫定位显示，蛋白聚糖沉积发生在共培养中，位于肝细胞索周围的基底膜样结构中。肝细胞在纯化的基底膜聚糖底物上的体外黏附试验表明，这些细胞可能通过属于β1家族的整合素与蛋白聚糖相互作用。这些数据表明，狄氏间隙中基底膜聚糖的沉积需要细胞间的协作。这篇关于基底膜聚糖（肝基底膜的第三种主要成分）的文章显示，它在肝脏中有独特的细胞来源，并且如同IV型胶原和层粘连蛋白一样，成年肝细胞在培养时会表达。
