Figure 7. Involvement of PDK1 in the induction by TSH of IL-6.

(A) Cultures were untreated (control) or bTSH (5 mIU/ml) was added to medium for 30 min. Cellular protein was subjected to Western blot analysis for PDK1 and pPDK1 and re-probed for β-actin. Results are representative of three separate experiments performed. Densitometric analysis; pPDK1, control fibroblasts, 16.25±2.85 AU; plus bTSH, 42.7±6.54 AU; control fibrocytes, 64.5±2.67 AU; plus TSH, 78.5±3.8 AU. In 3 separate experiments, TSH increased pPDK1 levels by 2.6±0.3-fold and 1.2±0.3-fold in fibroblasts and fibrocytes, respectively. (B) Sub- confluent cultures were transfected with either control siRNA or one targeting PDK1, followed by 48 h incubation. Cultures were treated with nothing or bTSH (5 mIU/mL) for 16 h, media collected and subjected to IL-6-specific ELISA and cell layers analyzed for protein content. Data are expressed as the mean ± SD of three independent determinations. Inset: Cell layers were subjected to Western blot analysis for PDK1 after transfection with control siRNA or that targeting PDK1. In 3 separate experiments, PDK1 siRNA reduced TSH-induced IL-6 levels by 73±4% in fibroblasts and 73±5% in fibrocytes. (C) Orbital fibroblasts, in this case from a patient with TAO, were transfected with PDK1siRNA while fibrocytes were treated with OSU-03012 (5 µM) for 6 h. Cultures were treated as indicated (bTSH, 5 mIU/mL) for 30 min. Cellular protein was subjected to Western blot analysis of PKCµ and pPKCµ in fibroblasts (left panel) and PKCβII and pPKCβII in fibrocytes (right panel). (D) Confluent cultures were pre-treated without or with OSU-03012 (5 µM) for 6 h, then treated with nothing (control) or bTSH (5 mIU/ml) for 30 min. Cellular proteins were subjected to Western blot analysis probing with AKT and pAKT antibodies. Inhibition of TSH-dependent pAKT by OSU-03012 in 3 separate experiments was 14.4±1.2% and 2.5±0.6% in fibroblasts and fibrocytes, respectively.