Figure 6

HSF1 inhibits autophagic flux. (a) Immunoblotting analysis of HSF1, Hsp70, p62, mTOR, phosphorylated mTOR (pS2448), p70 S6K, phosphorylated p70 S6K (pT389) in lysates from U2OS cells, which had been transfected with either control siRNA (siCTL) or HSF1 siRNA (siHSF1s or siHSF1sp) for 48 h, and subsequently treated with vehicle (0.1% DMSO) or HBB2 (3 µM) for 18 h, and supplemented with bafilomycin A1 (Baf-A1; 10 nM) or vehicle (0.1% DMSO) for a the last two hours of HBB2 treatment. The levels of β-actin served as a loading control. (b–d) Real-time PCR analysis of HSF1 (b), NRF2 (c), and p62 (d) from a parallel experiment described in (a) except without Baf-A1 treatment, in U2OS cells transfected with siCTL (10 nM) or siHSF1sp (10 nM). The mRNA levels of 18 S were used for normalization. The data are represented by means + SD from three independent transfections. Student’s t-test was used to test for statistical significance, where *represents p < 0.05 when comparing siCTL and siHSF1sp for each treatment pair. (e) Immunoblotting analysis of LC3B in lysates from U2OS cells, which had been transfected with either siCTL (10 nM) or siHSF1sp siRNA (10 nM) for 48 h, and subsequently treated with vehicle (0.1% DMSO) or HBB2 (3 µM) for 18 h, supplemented with bafilomycin A1 (Baf-A1; 10 nM) for the last 2 h. The levels of β-actin served as a loading control.