Fig. 4

Curcumin inhibit IFNAR1 reduction by disrupting 20S proteasome activities. a SH-SY5Y cells were infected with EV71 at an MOI of 5. 2 h later, the cells were post-treated with IFN-α (250 IU/mL) without or with DMSO or MG132 (5 μM) or Curcumin (5 or 20 μM) as the figure outlined. 10 h later, total cellular protein were extracted and used for the detection of IFNAR1, VP1 and β-actin (loading control) protein by western blot. b Densitometric analysis of the western blot results in a was conducted using Quantity One software. IFNAR1 and VP1 expression levels were normalized by β-actin expression level. SH-SY5Y cells were treated in parallel as shown in a, cell lysates were prepared, proteasomes (c) and deubiquitinating (d) activities were measured using a fluorogenic substrate SLLVY-AMC and ubiquitin-AMC as described in Materials and Methods, respectively. All the results indicate the mean ± SD of three independent experiments. Statistical analysis was performed using Student’s t-test, *P < 0.05, ** P < 0.01, *** P < 0.001, n.s. P > 0.05. EV, EV71; F, IFN-α; C, Curcumin