EFFECT OF TRANSFORMING GROWTH-FACTOR-BETA ON LIPOPROTEIN-LIPASE IN RAT MESENCHYMAL HEART CELL-CULTURES

The effect of recombinant transforming growth factor-beta 2 (rTGF-beta 2) on lipoprotein lipase (LPL) synthesis was studied in mesenchymal r at heart cell cultures. Addition of rTGF-beta 2 to culture medium cont aining 20% serum resulted in a time-dependent decrease in LPL activity . With 10 ng/ml a 30% fall occurred after 12 h and only 20% of enzyme activity remained after 24 h with 5 or 10 ng/ml. The minimal effective dose of rTGF-beta 2 was 0.1 ng/ml and a 20% decrease occurred after e xposure for 24 h. Antibodies specific to TGF-beta 2 blocked this effec t. The decrease in enzymic activity was accompanied by a decrease in e nzyme mass and LPL mRNA. Addition of rTGF-beta 2 was effective only du ring the first week in culture, when enzyme activity was increasing bu t not after 12 days when the cultures were overconfluent, and the enzy me activity was high.