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

Area of Science:

• Cellular Biology
• Molecular Biology
• Biochemistry

Background:

• The Interleukin-6 (IL-6)/Signal Transducer and Activator of Transcription 3 (STAT3) pathway regulates critical cellular processes like inflammation and proliferation.
• Carbon monoxide (CO) is a gaseous molecule produced from heme degradation, known to modulate various biological functions.

Purpose of the Study:

• To investigate the mechanism by which CO-releasing molecules (CORMs) inhibit IL-6-induced STAT3 activation in endothelial cells (ECs).
• To explore the role of protein glutathionylation and heme oxygenase-1 (HO-1) in mediating the effects of CORMs on STAT3 signaling.

Main Methods:

• Treatment of endothelial cells with CORMs and IL-6.
• Assessment of STAT3 phosphorylation, nuclear translocation, and transactivity.
• Measurement of intracellular GSSG levels and protein glutathionylation.
• Use of catalase and buthionine sulfoximine (BSO) to modulate antioxidant status and glutathione synthesis.
• Employing HO-1 siRNA to investigate the role of HO-1.

Main Results:

• CORMs suppressed IL-6-induced STAT3 phosphorylation, nuclear translocation, and transactivity in ECs.
• CORMs increased intracellular GSSG levels, leading to STAT3 glutathionylation.
• Catalase treatment reversed the inhibitory effects of CORMs on STAT3 phosphorylation.
• BSO treatment attenuated CORM-induced STAT3 glutathionylation and STAT3 phosphorylation inhibition.
• HO-1 expression was induced by CORMs, and HO-1 siRNA reduced CORM-induced STAT3 glutathionylation.

Conclusions:

• CO-mediated increase in GSSG levels augments protein glutathionylation, inhibiting STAT3 activation.
• CO-induced HO-1 expression enhances and sustains the inhibition of STAT3 signaling in IL-6-treated ECs.
• The findings elucidate a novel mechanism involving CO, oxidative stress, and glutathionylation in the regulation of the IL-6/STAT3 pathway.