Fig. 5.

Mechanisms of transcriptional regulation by HO-1. a Expression of IL-8 in confluent control shRNA- and HMOX1 shRNA-transduced Caco-2 IECs treated with IL-1β (1 ng/mL) +/– transcriptional blockade with actinomycin D after 1 h. b Expression of NRF2 protein at baseline normalized to cell density via crystal violet staining and presented as % of control. The activation of AP-1 (c) and NF-κB (d) transcription factors by IL-1β (1 ng/mL) was measured using luciferase reporter plasmid transfection in non-targeted control shRNA- and HMOX1 shRNA-transduced Caco-2 IECs. e Activation (phosphorylation) of p38 MAPK was assessed at baseline and in the setting of IL-1β treatment (1 ng/mL × 30 min) by cell-based ELISA. f The influence of inhibition of p38 MAPK on the increased expression of IL-8 in HMOX1 shRNA Caco-2 cells was assessed by pretreatment with a p38 MAPK inhibitor (p38i) SB202190 at 40 µM, 1 h prior to IL-1β (1 ng/mL) exposure for 2 h. Data represent the combined results from at least 3 independent experiments. * p < 0.05; ** p < 0.01.