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. 2013 Sep 26;9(9):e1003747. doi: 10.1371/journal.pgen.1003747

Figure 1. KHSRP and TTP down-regulate IL-8 expression by promoting degradation of IL-8 mRNA.

Figure 1

a, e). KHSRP (75 kD) (a) and TTP (36 kD) (e) were knocked down in NCI-H292 cells using si-RNA. Scrambled si-RNA (si-con) served as a control for specificity and β-actin (42 kD) was determined to verify equal protein loading. b, f). IL-8 released over 24 h in supernatant from NCI-H292 cells, non-transfected (nt) or transfected with si-con or si-KHSRP (b) or si-TTP (f), and either non-stimulated (ns) or stimulated with IL-17 (100 ng/ml), TNF-α (5 ng/ml) or TNF-α plus IL-17 (5 ng/ml+100 ng/ml, respectively). Data are shown as mean ± SD. 2-way ANOVA analysis was done with Bonferroni's multiple comparison post-test. ***P<0.001, **P<0.01, *P<0.05. c, g). Quantitative PCR (q-PCR) analysis of IL-8 mRNA was done for non-transfected or transfected cells with si-con or si-KHSRP (c) or si-TTP (g), at 2 h after stimulation with TNF-α or TNF-α plus IL-17, or left unstimulated. ***P<0.001, **P<0.01, *P<0.05 (2-way ANOVA, Bonferroni's multiple comparison post-test). The data presented is representative of 3 independent experiments done for each AUBp. mRNA results are presented relative to that of unstimulated, non-transfected cells. d, h). Non-transfected, si-con or si-KHSRP (d) or si-TTP (h) transfected cells were left unstimulated or stimulated with TNF-α or TNF-α plus IL-17 for 2 h. RNA was isolated from cells at 0, 30 and 60 minutes (mins) after blocking gene transcription by actinomycin D (5 µg/ml). % of IL-8 mRNA remaining was calculated on basis of q-PCR. Representative experiment is shown representative of 5 experiments.