Human spreading factor: Synthesis and response by HepG2 hepatoma cells in culture

✍ Scribed by David W. Barnes; Janet Reing

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 964 KB
• Volume: 125
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041250206

✦ Synopsis

Human serum spreading factor (SF) is a cell adhesion and spreading-promoting glycoprotein purified from serum or plasma that mediates effects in a wide variety of animal cell culture systems. HepG2 human hepatoma cells were found to synthesize and secrete SF into culture medium. Quantitative immunoassay of the protein indicated a concentration of about 1 j@nl in 48 hr-conditioned medium from confluent cultures. Although fibronectin also was synthesized and secreted into the culture medium, HepC2 cell spreading was observed in response to human serum SF, but not in response to human plasma fibronectin. lmmunoprecipitation of SF from culture medium of cells metabolically-labeled with leucine, fucose or glucosamine identified a single form of the molecule of approximately 70,000 daltons. Treatment of cultures with tunicamycin inhibited incorporation of fucose and glucosamine into immunoprecipitated SF, but did not prevent synthesis and secretion of the protein. Electrophoretic analysis and cell spreading assays showed that SF secreted by tunicamycin-treated HepG2 cells was of molecular weight (mw) approximately 60,000, and was biologically active.

Human serum spreading factor (SF) is a blood glycoprotein that promotes attachment and spreading and influences growth, migration and differentiation of animal cells in culture (Barnes