Distribution of type I collagen and basement membrane proteins in the cultures of cloned epithelial liver cells.

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Abstract
Cultures of a cloned epithelial cell lines derived from rat liver that synthesizes .alpha.-fetoprotein were used. Time courses of the appearance and distribution of types I and IV collagen, laminin and fibronectin in these cultures were assayed by the unlabeled peroxidase anti-peroxidase technique. Fibrillogenesis was monitored by the conventional phosphotungstic acid aniline-blue staining method for collagen fibrils. In the initial stage of cell proliferation, the antigenecities of these 4 matrix proteins were found only in the interior of most cells. Later, laminin and fibronectin began to appear in the intercellular spaces, although types I and IV collagens still were confined within the cells. With the onset of fibrillogenesis, extracellular deposition of types I and IV collagen began together with a relative decrease in the intensity of cellular staining. As fibrillogenesis progressed, these 4 matrix proteins gave more and more intense immunocytochemical reactions in the extracellular spaces, developing into the characteristic circular pattern of distribution. This process usually stopped when fibrillogenesis reached what appeared to be a static state. Immunocytochemical staining for the type I collagen of the preparations, then phosphotungstic acid aniline blue staining showed that 2 types of staining coincide. In contrast, none of 3 other matrix proteins showed complete codistribution with aniline blue positive fibrils. They were, however, located close to each other. Cultured epithelial liver cells produce these matrix proteins from a time early in culture and the extracellular depositions of these proteins take place successively with some interrelation.