Limits...
Carbon monoxide induces heme oxygenase-1 to modulate STAT3 activation in endothelial cells via S-glutathionylation.

Yang YC, Huang YT, Hsieh CW, Yang PM, Wung BS - PLoS ONE (2014)

Bottom Line: The inhibition of glutathione synthesis by BSO was also found to attenuate STAT3 glutathionylation and its inhibition of STAT3 phosphorylation.We further found that HO-1 increases STAT3 glutathionylation and that HO-1 siRNA attenuates CORM-induced STAT3 glutathionylation.Hence, the inhibition of STAT3 activation is likely to occur via a CO-mediated increase in the GSSG level, which augments protein glutathionylation, and CO-induced HO-1 expression, which may enhance and maintain its effects in IL-6-treated ECs.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Immunology and Biopharmaceuticals, National Chiayi University, Chiayi, Taiwan, ROC.

ABSTRACT
IL-6/STAT3 pathway is involved in a variety of biological responses, including cell proliferation, differentiation, apoptosis, and inflammation. In our present study, we found that CO releasing molecules (CORMs) suppress IL-6-induced STAT3 phosphorylation, nuclear translocation and transactivity in endothelial cells (ECs). CO is a byproduct of heme degradation mediated by heme oxygenase (HO-1). However, CORMs can induce HO-1 expression and then inhibit STAT3 phosphorylation. CO has been found to increase a low level ROS and which may induce protein glutathionylation. We hypothesized that CORMs increases protein glutathionylation and inhibits STAT3 activation. We found that CORMs increase the intracellular GSSG level and induce the glutathionylation of multiple proteins including STAT3. GSSG can inhibit STAT3 phosphorylation and increase STAT3 glutathionylation whereas the antioxidant enzyme catalase can suppress the glutathionylation. Furthermore, catalase blocks the inhibition of STAT3 phosphorylation by CORMs treatment. The inhibition of glutathione synthesis by BSO was also found to attenuate STAT3 glutathionylation and its inhibition of STAT3 phosphorylation. We further found that HO-1 increases STAT3 glutathionylation and that HO-1 siRNA attenuates CORM-induced STAT3 glutathionylation. Hence, the inhibition of STAT3 activation is likely to occur via a CO-mediated increase in the GSSG level, which augments protein glutathionylation, and CO-induced HO-1 expression, which may enhance and maintain its effects in IL-6-treated ECs.

Show MeSH

Related in: MedlinePlus

CO increases the GSSG level in ECs.A. and B. ECs were exposed to TCDC or MC for 1, 3, 6 and 12 hours and the intracellular SGGS levels were then measured. The results shown are the mean ± SEM. *P<0.05 compared with untreated ECs. C. and D. The intracellular GSH levels of ECs incubated with TCDC or MC for 1, 3, 6 and 12 hours. Results are presented as the mean ± SEM (n = 3). *P<0.05 compared with untreated ECs.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4114553&req=5

pone-0100677-g004: CO increases the GSSG level in ECs.A. and B. ECs were exposed to TCDC or MC for 1, 3, 6 and 12 hours and the intracellular SGGS levels were then measured. The results shown are the mean ± SEM. *P<0.05 compared with untreated ECs. C. and D. The intracellular GSH levels of ECs incubated with TCDC or MC for 1, 3, 6 and 12 hours. Results are presented as the mean ± SEM (n = 3). *P<0.05 compared with untreated ECs.

Mentions: We have reported previously that HO-1 can be induced by oxidative stress [33]. Nevertheless, CO has long been known to increase low level ROS via the inhibition of cytochrome c oxidase by competing with oxygen binding [13], [14]. We thus examined intracellular ROS formation in CORM-treated ECs. As shown in Figure 3A and 3B, TCDC and MC can both increase the intracellular ROS level and superoxide levels (Figure 3C and D). CORM-treated ECs were pretreated with the anti-oxidant enzyme catalase and showed reduced ROS formation (Figure 3A and B). This may in turn enhance the GSSG level and induce protein glutathionylation, as demonstrated by our previous findings [15]. We therefore analyzed in our current study whether CO modulates the intracellular redox homeostasis in BAECs. As shown in Figure 4A and B, TCDC or MC increase the intracellular GSSG level after three hour of treatment. However, we also found that TCDC or MC increase the intracellular GSH level (Figure 4C and 4D). Although CORMs could induce a significant increase in GSSG, the GSH/GSSG ratio have different recovery time course after CORMs treatment. (Figure S3 A and B).


Carbon monoxide induces heme oxygenase-1 to modulate STAT3 activation in endothelial cells via S-glutathionylation.

Yang YC, Huang YT, Hsieh CW, Yang PM, Wung BS - PLoS ONE (2014)

CO increases the GSSG level in ECs.A. and B. ECs were exposed to TCDC or MC for 1, 3, 6 and 12 hours and the intracellular SGGS levels were then measured. The results shown are the mean ± SEM. *P<0.05 compared with untreated ECs. C. and D. The intracellular GSH levels of ECs incubated with TCDC or MC for 1, 3, 6 and 12 hours. Results are presented as the mean ± SEM (n = 3). *P<0.05 compared with untreated ECs.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4114553&req=5

pone-0100677-g004: CO increases the GSSG level in ECs.A. and B. ECs were exposed to TCDC or MC for 1, 3, 6 and 12 hours and the intracellular SGGS levels were then measured. The results shown are the mean ± SEM. *P<0.05 compared with untreated ECs. C. and D. The intracellular GSH levels of ECs incubated with TCDC or MC for 1, 3, 6 and 12 hours. Results are presented as the mean ± SEM (n = 3). *P<0.05 compared with untreated ECs.
Mentions: We have reported previously that HO-1 can be induced by oxidative stress [33]. Nevertheless, CO has long been known to increase low level ROS via the inhibition of cytochrome c oxidase by competing with oxygen binding [13], [14]. We thus examined intracellular ROS formation in CORM-treated ECs. As shown in Figure 3A and 3B, TCDC and MC can both increase the intracellular ROS level and superoxide levels (Figure 3C and D). CORM-treated ECs were pretreated with the anti-oxidant enzyme catalase and showed reduced ROS formation (Figure 3A and B). This may in turn enhance the GSSG level and induce protein glutathionylation, as demonstrated by our previous findings [15]. We therefore analyzed in our current study whether CO modulates the intracellular redox homeostasis in BAECs. As shown in Figure 4A and B, TCDC or MC increase the intracellular GSSG level after three hour of treatment. However, we also found that TCDC or MC increase the intracellular GSH level (Figure 4C and 4D). Although CORMs could induce a significant increase in GSSG, the GSH/GSSG ratio have different recovery time course after CORMs treatment. (Figure S3 A and B).

Bottom Line: The inhibition of glutathione synthesis by BSO was also found to attenuate STAT3 glutathionylation and its inhibition of STAT3 phosphorylation.We further found that HO-1 increases STAT3 glutathionylation and that HO-1 siRNA attenuates CORM-induced STAT3 glutathionylation.Hence, the inhibition of STAT3 activation is likely to occur via a CO-mediated increase in the GSSG level, which augments protein glutathionylation, and CO-induced HO-1 expression, which may enhance and maintain its effects in IL-6-treated ECs.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Immunology and Biopharmaceuticals, National Chiayi University, Chiayi, Taiwan, ROC.

ABSTRACT
IL-6/STAT3 pathway is involved in a variety of biological responses, including cell proliferation, differentiation, apoptosis, and inflammation. In our present study, we found that CO releasing molecules (CORMs) suppress IL-6-induced STAT3 phosphorylation, nuclear translocation and transactivity in endothelial cells (ECs). CO is a byproduct of heme degradation mediated by heme oxygenase (HO-1). However, CORMs can induce HO-1 expression and then inhibit STAT3 phosphorylation. CO has been found to increase a low level ROS and which may induce protein glutathionylation. We hypothesized that CORMs increases protein glutathionylation and inhibits STAT3 activation. We found that CORMs increase the intracellular GSSG level and induce the glutathionylation of multiple proteins including STAT3. GSSG can inhibit STAT3 phosphorylation and increase STAT3 glutathionylation whereas the antioxidant enzyme catalase can suppress the glutathionylation. Furthermore, catalase blocks the inhibition of STAT3 phosphorylation by CORMs treatment. The inhibition of glutathione synthesis by BSO was also found to attenuate STAT3 glutathionylation and its inhibition of STAT3 phosphorylation. We further found that HO-1 increases STAT3 glutathionylation and that HO-1 siRNA attenuates CORM-induced STAT3 glutathionylation. Hence, the inhibition of STAT3 activation is likely to occur via a CO-mediated increase in the GSSG level, which augments protein glutathionylation, and CO-induced HO-1 expression, which may enhance and maintain its effects in IL-6-treated ECs.

Show MeSH
Related in: MedlinePlus