Cell density dependent effects of TGF-β demonstrated by a plasminogen activator-based assay for TGF-β

✍ Scribed by Robert Flaumenhaft; Daniel B. Rifkin

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 857 KB
• Volume: 152
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041520107

✦ Synopsis

Transforming growth factor-pl (TGF-Pl) induces a decrease in plasminogen activator (PA) expression in confluent cultures of bovine aortic endothelial (BAE) cells We describe an assay using the suppression of PA expression in confluent BAE cells by TGF-P1 which detects concentrations of the growth factor ranging from 5 to LOO pgiml and has an ED, , of 15-20 pg/mI. The assay can be performed in 96-well plates and requires a minimum of 35 uI of solution per sample, thereby limiting the amount of reagents required and allowing many samples to be tested in a single assay. Here we demonstrate that the effect of TGF-PI on PA expression in BAE cells depends on the length of time the cells are exposed to the growth factor and the density at which the cells are plated In cells plated at a high density ( 3 5 x lo5 cells/cm2), both 4 h and 24 h exposures to TGF-p1 suppress PA expression. However, with cells plated sparsely (3 5 x lo4 cellsicm2), a 4 h exposure to TGF-PI increases PA expression Z-fold, whereas a 24 h exposure rcsults in an 85% inhibition of basal PAexpression The paradoxical stimulation ot PA expression in cells at a sparse density upon 4 h exposure to TGF-pl occurs in a dose-dependent manner with an ED, , of 15-20 pg/ml This bifunctional response of PA production in cells exposed to TGF-P1 may have implications with regard to the role of TGF-PI in angiogenesis