Crocin Suppresses LPS-Stimulated Expression of Inducible Nitric Oxide Synthase by Upregulation of Heme Oxygenase-1 via Calcium/Calmodulin-Dependent Protein Kinase 4
Figure 1
Induction of HO-1 by crocin. (a) Chemical structure of crocin. (b) RAW 264.7 cells were incubated with the indicated concentrations of crocin for 24 h, after which cell viability was measured by MTT assay. (c) RAW 264.7 cells were treated with the indicated concentrations of crocin for 6 h (upper panel) or with 500 μM crocin for various periods (lower panel), and HO-1 protein levels were analyzed by Western blotting. (d) Cells were treated with the indicated concentrations of crocin for 3 h or with 500 μM crocin for various periods and HO-1 mRNA levels were measured by RT-PCR. (e) Cells were treated with crocin (500 μM) for 6 h in the presence of Act. D (1 μg/mL) or CHX (1 μg/mL), after which protein levels of HO-1 were measured by Western blotting. (f) Cells were transfected with HO-1 promoter-luciferase construct and then treated with the indicated concentration of crocin or CoPP (10 μM). Equal amounts of cell extracts were then assayed for dual luciferase activity. versus the group treated with PBS (vehicle). GAPDH and tubulin were used as loading controls.
