Role of CHOP in SFA-induced GDF15 expression. (A,B) GDF15 expression measured by RT-qPCR after treatment with 200 µM C18:0 for 16 h in PMA-differentiated THP-1 after ATF3 or CHOP silencing by siRNA (n = 4). (C) Schematic representation of GDF15 promoter with the putative CHOP response elements and the regions analyzed in ChIP-qPCR. (D) CHOP binding in GDF15 promoter measured by ChIP-qPCR in PMA-differentiated THP-1 cells treated with 200 µM C18:0 for 16 h (n = 4). (E) Analysis of CHOP, BIP and eIF2α phosphorylation by western blot after stimulation of PMA-differentiated THP-1 cells with 200 µM SFAs or 5 µg/mL tunicamycin for 24 h (n = 3). HSP90, HSP60 and eIF2α were used as loading control.* p < 0.05, ** p < 0.01, *** p < 0.001 by two-way ANOVA with Sidak’s multiple comparisons test. Results are presented as mean ± SEM. FC, Fold change. TSS, transcription start site.