Fig. 5.

Effect of cell-penetrating interfering peptide on PAI-1 mRNA levels. (A) Dose-response of the peptides. 3T3L1 adipocytes (day 8) were treated with increasing concentrations (0–40 μM) of either specific or control peptide for 6 h, followed by treatment with or without 1 μM insulin for 2 h. Total RNA was prepared, and levels of PAI-1 and GAPDH (loading control) mRNAs were measured by Northern blot hybridization. Ribosomal RNAs were stained with methylene blue to serve as an additional control for equal loading and blotting. (B) Effect of the peptides on PAI-1 mRNA levels, which are elevated under insulin-resistant conditions. Cells were serum-starved and then treated with 40 μM of specific or control peptides for 12 h. Cells were then treated with MBCD for 40 min, followed by insulin (100 nM) for 2 h. Total RNA was prepared and analyzed for PAI-1 mRNA as above.