Fig. 3

Induction of TGF-β mRNA expression by insulin and TNF-α.

(A) Six-week-old lean mice were injected intraperitoneally either with 10 units of insulin, with 4 µg of murine recombinant TNF-α, or with saline. The epididymal fat pads were removed 3, 6, and 24 hr later and total RNA was prepared and analyzed for TGF-β gene expression by quantitative RT-PCR as described in Materials and Methods. Each time point on the graph represents the mean ± SD of 3 animals. (B) 3T3-L1 adipocytes were grown and differentiated in 6-well tissue culture plates. The washed and differentiated cells were then treated with insulin (100 nM), TNF-α (5 ng/ml), or media alone for the indicated times, and total RNA was isolated and the steady-state levels of TGF-β mRNA were determined using quantitative RT-PCR. n = 6 ± SD.