Liver epithelial cell migration induced by epidermal growth factor or transforming growth factor alpha is associated with changes in the gene expression of secreted proteins

Abstract

Rat liver epithelial cells are induced to migrate by epidermal growth factor (EGF) or transforming growth factor alpha (TGF-alpha) in serum-free medium supplemented with insulin. Immunohistological staining of the migration tracks containing laminin and fibronectin has allowed a quantitative analysis of the process. The growth factor-induced migration is relatively slow, but very efficient. Between 24 and 48 h after exposure to EGF (or TGF-alpha), 50 to 70% of the cells have migrated away from their site of initial attachment and spreading. This delayed effect of the interaction of the receptor with its ligands is associated with changes in gene expression, but is not associated with a stimulation of cell proliferation. In serum-free medium supplemented with insulin, the cells secrete six major proteins, as revealed by SDS-polyacrylamide gel electrophoresis. The media of cultures supplemented with insulin plus EGF (or TGF-alpha) contain in addition two new proteins and an increased amount of fibronectin. One secreted protein is synthesized in significantly reduced amounts. The most conspicuously EGF-induced protein (EIP-1; Mr 47,000) is detected within 2 h, depends on the continued presence of the growth factor, and has not been detected as bound to the substratum. The stringent regulation of EIP-1 suggests that this gene product might participate in the modulation of the changes induced by the growth factor. The system is being used for the further analysis of the regulation of gene expression by EGF and of the migration of normal and neoplastically transformed epithelial cells.

Adenine nucleotides stimulate migration in wounded cultures of kidney epithelial cells.

“…TGF-f has been shown to modulate cellular production of matrix proteins, plasminogen activator, and plasminogen activator inhibitor (30,47), and EGF stimulates transcription of integrins in 3T3 fibroblasts (48). In rat liver epithelial cells, EGF-induced migration is associated with altered fibronectin and laminin gene expression (49), and ECM proteins appear to modulate migration (50). In addition, activation of fibronectin receptor function has been demonstrated in keratinocytes during cutaneous wound healing (5 1), and specific integrin subunits were detected in migrating, but not resting, keratinocytes (52).…”

Cellular fibronectin is induced by epidermal growth factor, but not by dexamethasone or cyclic AMP in rat liver epithelial cells

“…We have recently reported that rat liver epithelial cells induced to migrate by EGF deposit ECM migration tracks that contain FN as one of its components, and also synthesize increased amounts of the protein [4]. We now show that the induction of FN by EGF occurs shortly after exposure of the cells to the growth factor and is associated with an increase in the amount of mRNA for the cellular type of FN.…”

“…FN is also required for migration during development (e.g., neural crest cells [2]) and is involved in liver tissue repair [3] and liver cell migration [4]. From the single FN gene, up to 12 (rat [5]) or 20 (human [18]) variants can be derived by differential splicing of the primary transcript.…”

Plasminogen activator inhibitor 1: Mechanisms of its synergistic regulation by growth factors

“…EGF-stimulated PAI-1 (earlier reported as EGF/TGFα-inducible protein EIP-1) synthesis is closely associated with EGF-induced cell migration in both normal and Ha-Ras-transformed liver epithelial cells (Bade and Feindler 1988;Manske, Feindler et al 1990;Seebacher, Manske et al 1992). …”

“…Thalacker and Nilsen-Hamilton 1987; Bade and Feindler 1988), and these proteins are deposited into the ECM migration tracks (Seebacher, Manske et al 1992). However, PAI-1…”