(A) Schematic figure of putative binding sites for XBP1 in the KDEL receptor genes (arrows).
(B and C) ATF6 and XBP1 activity was induced in HEK293DAX cells by a 16 hr incubation in 10 mM trimethoprim (TMP) and/or 1 μg/mL doxycycline (DOX), and expression levels of (B) BiP and ERdj4 and (C) KDEL receptors were analyzed using real-time RT-qPCR (n = 8–9).
(D) XBP1 splicing was inhibited by a 1hr pretreatment with 1 or 3 μM KIRA6, and changes in KDEL receptor expression were assessed after exposure of SH-SY5Y cells to 100 nM Tg for 8 hr (n = 6–9).
(E) Extracellular GLuc-ASARTDL from cells described in (D) (n = 6).
All transcription results are shown as 2−ddCq (mean ± upper and lower limit) with *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001 versus control groups using two-way ANOVA followed by Tukey’s test. In (B) and (C): ##p < 0.01, ####p < 0.0001 as compared to TMP only, and %%p < 0.01, %%%%p < 0.0001 as compared to DOX only. In (D): ####p < 0.0001 as compared to 0 mM KIRA6/Tg and %%p < 0.01 as compared to 1 μM KIRA6/Tg. See also Figure S6 and Table S1.