Fig. 4.

Inhibition of PERK disrupts the UPR and renders the X-ALD fibroblasts more susceptible to ER stress. a Representative immunoblots for cleaved-ATF6, total PERK, P-PERK, total eIF2α, P-eIF2α, ATF4, CHOP, GADD34, GRP78, GRP94 and PDI levels in control (Ctrl) and X-ALD human fibroblasts pretreated with or without the PERK inhibitor GSK2606414 (GSK, 120 nM) for 1 h and then exposed to tunicamycin (TM, 2 µg/mL) for 48 h. Protein levels were normalized relative to γ-tubulin (γ-Tub). The histograms below show the cleaved-ATF6, P-PERK, P-eIF2α, ATF4, CHOP, GADD34, GRP94, GRP78 and PDI levels normalized relative to γ-Tub and the P-PERK/PERK and P-eIF2α/eIF2α ratios relative to their respective WT values. b Real-time RT-PCR analyses of Edem2 and Herpud1 mRNA levels in Ctrl and X-ALD human fibroblasts pretreated with or without the PERK inhibitor GSK2606414 (GSK; 120 nM) for 1 h and then exposed to tunicamycin (TM, 2 µg/mL) for 48 h. All values are expressed as the mean ± SD (n = 4 by genotype and condition; *P < 0.05 and **P < 0. 01, one-way ANOVA followed by Tukey’s HSD post hoc test)