mRNA expression induced by cell-substrate interaction. A two-dimensional tissue formation process.

Abstract

This study aimed to develop a quantitative assay method of determining cellular events at the mRNA level during tissue formation. Quantitative assessment of mRNAs coding specific proteins (beta-actin, fibronectin, laminin) during tissue formation on tissue culture dishes was attained using a Northern blot technique with autoradiography. The amount of beta-actin mRNA, the expression of which is initiated shortly after adhesion, greatly increased with incubation time and reached maximal levels near the confluent state, followed by a reduced expression at a later stage of tissue formation. The time course of beta-actin mRNA expression, which reflects cytoskeletal organization, corresponded well to morphologic changes in adherent cells. Expression of mRNAs coding the extracellular matrix proteins, fibronectin and laminin, was initiated at the proliferation stage. After maximum expression levels were observed at the confluent stage, a gradual decrease in the expression of both mRNAs was seen after longer culture periods. Expression patterns of mRNAs coding cytoskeletal and extracellular matrix proteins greatly depended upon the type of artificial substrates. Thus, the dynamic changes in tissue formation were quantified to elucidate the significance of artificial substrates in tissue formation at the mRNA level.