The cystathionine γ-lyase/hydrogen sulfide system maintains cellular glutathione status.
Hydrogen sulfide (H2S) has been implicated to exhibit antioxidative properties in many models. CSE (cystathionine γ-lyase) is an important enzyme responsible for endogenous H2S production in mammalian systems, but little is known about the modulation of endogenous H2S production and its antioxidative activity. We found that inhibiting CSE activity with PAG (propargylglycine) or silencing CSE expression using an siRNA approach resulted in a greater reduction in cell viability under exposure to the oxidizing agent hydrogen peroxide (H2O2). Cellular oxidative stress also increased significantly upon PAG inhibition or CSE knockdown. Further experiments using an activity-null Y60A mutant, a hyperactive E339A mutant and a control E349A mutant demonstrated that modulation of CSE catalytic activity altered its antioxidative activity. The increased sensitivity towards H2O2-induced cytotoxicity in CSE-siRNA-transfected cells was associated with a decreased glutathione concentration (GSH) and glutathione ratio (GSH/GSSG). Incubation of cells with exogenous H2S increased the GSH concentration and GSH/GSSG ratio. Moreover, exogenous H2S preserved the cellular glutathione status under BSO (buthionine sulfoximine)-induced glutathione depletion. Taken together, the results of the present study provide molecular insights into the antioxidative activity of CSE and highlights the importance of the CSE/H2S system in maintaining cellular glutathione status.
*Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
Zheng-Wei
ZW
Lee
*Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
Yi-Lian
YL
Low
*Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
Shufen
S
Huang
†Department of Pharmacy, Henan University, Kaifeng, Henan 475004, People's Republic of China.
Tianxiao
T
Wang
*Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
Lih-Wen
LW
Deng
D000480:Alkynes / Q000494:pharmacology; D000975:Antioxidants / Q000502:physiology*; D002470:Cell Survival; D003542:Cystathionine gamma-Lyase / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D005978:Glutathione / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism*; D014162:Transfection
D000480:Alkynes; D000975:Antioxidants; C009055:propargylglycine; D003542:Cystathionine gamma-Lyase; D005978:Glutathione; D005998:Glycine; D006862:Hydrogen Sulfide