Miyabayashi C, Kojima T, Inoue K, Sasaki H, Muragaki Y, Ooshima A
Gastroenterol Jpn. 1987 Jun;22(3):354-69. doi: 10.1007/BF02774262.
Type IV collagen and laminin are major components of basement membrane (BM), whereas prolyl hydroxylase (PH) is a key enzyme in the hydroxylation of proline to hydroxyproline in collagen synthesis. In order to elucidate the exact mechanism of the formation of BM, immune electron microscopic observation of type IV collagen, laminin and PH was made in rat liver with marked proliferation of bile ducts following ligation of the common bile duct. Extracellular localization of type IV collagen was found in the BM of bile ducts and blood vessels and in the space of Disse in both normal rat liver and the liver of rats undergoing operation. Type IV collagen was localized in lamina rara and lamina densa. Laminin was codistributed with type IV collagen in BM but rarely in the space of Disse even in the liver of rats undergoing operation. Immunostaining of laminin was diffusely spread in lamina densa, but sparsely in lamina rara. Though no reaction products of type IV collagen and laminin were detected in the cytoplasm of normal biliary epithelial cells, they were found in rough endoplasmic reticulum (rER) and the vesicles close to the basal surfaces of the plasma membrane of the proliferating biliary epithelial cells. No evident localization of these components in Golgi apparatus was found. PH was found in rER of the biliary epithelial cells, hepatocytes, endothelial cells of vessels, fibroblasts and perisinusoidal cells except for Kupffer cells in normal rat liver. More intense and diffuse staining of PH was observed in rER in the proliferating biliary epithelial cells of the liver of rats undergoing operation in concomitance with the evident localization of type IV collagen in this organelle. These findings suggest that the major components of BM, such as type IV collagen and laminin in the proliferating biliary epithelial cells, are produced in rER and secreted by vesicles to the basal extracellular spaces, thus forming new BM in these circumstances.
IV型胶原蛋白和层粘连蛋白是基底膜（BM）的主要成分，而脯氨酰羟化酶（PH）是胶原蛋白合成过程中脯氨酸羟化为羟脯氨酸的关键酶。为了阐明BM形成的确切机制，我们对胆总管结扎后胆管明显增生的大鼠肝脏进行了IV型胶原蛋白、层粘连蛋白和PH的免疫电镜观察。在正常大鼠肝脏和手术大鼠肝脏中，IV型胶原蛋白的细胞外定位均见于胆管和血管的BM以及狄氏间隙。IV型胶原蛋白定位于透明层和致密层。层粘连蛋白与IV型胶原蛋白在BM中共分布，但即使在手术大鼠肝脏的狄氏间隙中也很少见。层粘连蛋白的免疫染色在致密层中弥漫分布，但在透明层中稀疏分布。虽然在正常胆管上皮细胞的细胞质中未检测到IV型胶原蛋白和层粘连蛋白的反应产物，但在增生胆管上皮细胞质膜基底表面附近的粗面内质网（rER）和小泡中发现了它们。在高尔基体中未发现这些成分的明显定位。在正常大鼠肝脏中，除库普弗细胞外，在胆管上皮细胞、肝细胞、血管内皮细胞、成纤维细胞和窦周细胞的rER中发现了PH。在手术大鼠肝脏增生胆管上皮细胞的rER中观察到PH的染色更强烈且弥漫，同时IV型胶原蛋白在该细胞器中有明显定位。这些发现表明，增生胆管上皮细胞中BM的主要成分，如IV型胶原蛋白和层粘连蛋白，在rER中产生，并通过小泡分泌到基底细胞外空间，从而在这些情况下形成新的BM。
