Fig. 1
From: Redox modifications of cysteine residues regulate the cytokine activity of HMGB1
The cytokine-stimulating activity of HMGB1 requires the presence of a disulfide bond between C23-C45 and the C106 residue in its fully reduced form. a Dose-dependent effect of DTT on the TNF-α-stimulating activity of HMGB1 (1 µg/ml, 16 h incubation), indicating that DTT prevented the formation of a disulfide bridge between C23 and C45. *P < 0.05 versus HMGB1 alone without DTT. N = 3. One-way ANOVA followed by Tukey’s multiple comparisons tests. b Lack of DTT-mediated effect on LPS regarding its TNF-α-stimulating activity. c Time-dependent effect of DTT on the TNF-α-stimulating activity of HMGB1. One-way ANOVA followed by Tukey’s multiple comparisons test between groups. *p < 0.05 versus HMGB1 without DTT. d The effect of mercury (Hg) on TNF-α release induced by recombinant HMGB1 prepared in the absence of DTT. Mercury selectively binds to thiol side chains. The results implicate that out of the 3 cysteines expressed in HMGB1 it must be C106 carrying a thiol side chain in TNF-α-inducing HMGB1, since C23 and C45 are engaged in a disulfide bond. n = 3. Two-way ANOVA followed by Sidak’s multiple comparisons test between groups. *p < 0.05 versus Hg-HMGB1