Figure 3.

PDGF activates select members of the AP-1 family of transcription factors. A: Nuclear extracts from pBSMC treated with 30 ng/ml PDGF or vehicle for two hours were assayed using a transcription factor ELISA to determine DNA-binding activity of AP-1 proteins. The graph shows AP-1 binding expressed as a percentage of control for each of 7 AP-1 subunits and data are representative of at least two independent experiments, each performed in duplicate. Increased binding of c-jun, JunB, Fos, Fra1, and Fra2 proteins to a consensus AP-1 oligonucleotide was observed in PDGF-treated cells (black bar) relative to controls (gray bar). JunD and FosB binding was unaffected by PDGF stimulation. B: Nuclear extracts from pBSMC pretreated for 30 minutes without (gray, black bar) or with (stippled, striped bar) 10 μmol/L triciribine followed by vehicle (gray, striped bar) or PDGF (black bar, stippled) for two hours were assayed as in (A). The graph shows AP-1 binding expressed as a percentage of control (vehicle or triciribine alone control). Data are representative of two independent trials. Inhibition of Akt ablated PDGF-induced DNA binding of c-jun and Fra1 but not Fos (compare stippled and black bar).