FIG. 4.
H2S attenuates IL-6-induced STAT3 phosphorylation, dimerization, translocation, and transcriptional function in a JAK2-independent manner. (A) NaHS suppressed IL-6 (10 ng/ml)-induced STAT3 phosphorylation in Huh7 cells, whereas p-JAK2 levels remained unchanged. (B) Representative native PAGE revealed reduced STAT3 dimerization in response to NaHS. (C) Representative immunofluorescence images illustrated that NaHS successfully suppressed p-STAT3 nuclear translocation induced by IL-6. (D) NaHS effectively inhibited IL-6 (10 ng/ml)-evoked STAT3 transcriptional activity assessed by an SIE reporter (n=5). (E) A similar result was demonstrated for the mRNA level of SOCS3, a target gene of STAT3 (n=3). (F, G) Stattic (10 μM), a potent inhibitor of STAT3 activation, dramatically blocked STAT3 phosphorylation (F) and HAMP induction (G) by IL-6 (10 ng/ml, n=3). GAPDH served as the loading control. Representative immunoblots and immunofluorescence images are presented with densitometry analysis in the Supplementary Data. Values are presented as mean±SEM from at least three independent experiments. ##p<0.01 compared with the control group; *p<0.05 and **p<0.01 compared with the IL-6 group. SIE, sis-inducible element. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars