Cell-cell contact and growth regulation of pinocytosis in 3T3 cells

✍ Scribed by Davies, Peter F.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1980
• Tongue: English
• Weight: 423 KB
• Volume: 13
• Category: Article
• ISSN: 0091-7419
• DOI: 10.1002/jss.400130209

✦ Synopsis

Abstract

In sub‐confluent cultures of Balb/c‐3T3 cells, pinocytosis rates were increased after exposure to specific growth factors (serum; platelet‐derived growth factor, PDGF; epidermal growth factor, EGF). Conversely, as cells became growth‐inhibited with increasing culture density, there was a corresponding decline in pinocytosis rate per cell. In order to test whether density‐inhibition of pinocytosis was influenced either by the growth cycle or by cell contact independently of growth, cells were induced into a quiescent state at a range of subconfluent and confluent densities. Under such conditions, cell density did not significantly inhibit pinocytosis rate. When confluent quiescent cultures in 2.5% serum were exposed to 10% serum, the resulting round of DNA synthesis was accompanied by enhanced pinocytosis per cell, even though the cells were incontact with one another. Furthermore, in a SV40‐viral transformed 3T3 cell line, both the growth fraction and the pinocytosis rate per cell remained unchanged over a wide range of culture densities. These studies indicate that density‐dependent inhibition of pinocytosis in 3T3 cells appears to be secondary to growth‐inhibition rather than to any direct physical effects of cell–cell contact.