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Effects of inhibiting antioxidant pathways on cellular hydrogen sulfide and polysulfide metabolism.
Free Radic Biol Med. 2019 05 01; 135:1-14.FR

Abstract

Elaborate antioxidant pathways have evolved to minimize the threat of excessive reactive oxygen species (ROS) and to regulate ROS as signaling entities. ROS are chemically and functionally similar to reactive sulfur species (RSS) and both ROS and RSS have been shown to be metabolized by the antioxidant enzymes, superoxide dismutase and catalase. Here we use fluorophores to examine the effects of a variety of inhibitors of antioxidant pathways on metabolism of two important RSS, hydrogen sulfide (H2S with AzMC) and polysulfides (H2Sn, where n = 2-7, with SSP4) in HEK293 cells. Cells were exposed to inhibitors for up to 5 days in normoxia (21% O2) and hypoxia (5% O2), conditions also known to affect ROS production. Decreasing intracellular glutathione (GSH) with l-buthionine-sulfoximine (BSO) or diethyl maleate (DEM) decreased H2S production for 5 days but did not affect H2Sn. The glutathione reductase inhibitor, auranofin, initially decreased H2S and H2Sn but after two days H2Sn increased over controls. Inhibition of peroxiredoxins with conoidin A decreased H2S and increased H2Sn, whereas the glutathione peroxidase inhibitor, tiopronin, increased H2S. Aminoadipic acid, an inhibitor of cystine uptake did not affect either H2S or H2Sn. In buffer, the glutathione reductase and thioredoxin reductase inhibitor, 2-AAPA, the glutathione peroxidase mimetic, ebselen, and tiopronin variously reacted directly with AzMC and SSP4, reacted with H2S and H2S2, or optically interfered with AzMC or SSP4 fluorescence. Collectively these results show that antioxidant inhibitors, generally known for their ability to increase cellular ROS, have various effects on cellular RSS. These findings suggest that the inhibitors may affect cellular sulfur metabolism pathways that are not related to ROS production and in some instances they may directly affect RSS or the methods used to measure them. They also illustrate the importance of carefully evaluating RSS metabolism when biologically or pharmacologically attempting to manipulate ROS.

Authors+Show Affiliations

Indiana University School of Medicine - South Bend, South Bend, IN, 46617, USA; Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA. Electronic address: kolson@nd.edu.Indiana University School of Medicine - South Bend, South Bend, IN, 46617, USA.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30790656

Citation

Olson, Kenneth R., and Yan Gao. "Effects of Inhibiting Antioxidant Pathways On Cellular Hydrogen Sulfide and Polysulfide Metabolism." Free Radical Biology & Medicine, vol. 135, 2019, pp. 1-14.
Olson KR, Gao Y. Effects of inhibiting antioxidant pathways on cellular hydrogen sulfide and polysulfide metabolism. Free Radic Biol Med. 2019;135:1-14.
Olson, K. R., & Gao, Y. (2019). Effects of inhibiting antioxidant pathways on cellular hydrogen sulfide and polysulfide metabolism. Free Radical Biology & Medicine, 135, 1-14. https://doi.org/10.1016/j.freeradbiomed.2019.02.011
Olson KR, Gao Y. Effects of Inhibiting Antioxidant Pathways On Cellular Hydrogen Sulfide and Polysulfide Metabolism. Free Radic Biol Med. 2019 05 1;135:1-14. PubMed PMID: 30790656.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of inhibiting antioxidant pathways on cellular hydrogen sulfide and polysulfide metabolism. AU - Olson,Kenneth R, AU - Gao,Yan, Y1 - 2019/02/19/ PY - 2018/12/17/received PY - 2019/02/12/revised PY - 2019/02/12/accepted PY - 2019/2/23/pubmed PY - 2020/5/22/medline PY - 2019/2/22/entrez KW - Antioxidants KW - Reactive oxygen species KW - Reactive sulfur species SP - 1 EP - 14 JF - Free radical biology & medicine JO - Free Radic Biol Med VL - 135 N2 - Elaborate antioxidant pathways have evolved to minimize the threat of excessive reactive oxygen species (ROS) and to regulate ROS as signaling entities. ROS are chemically and functionally similar to reactive sulfur species (RSS) and both ROS and RSS have been shown to be metabolized by the antioxidant enzymes, superoxide dismutase and catalase. Here we use fluorophores to examine the effects of a variety of inhibitors of antioxidant pathways on metabolism of two important RSS, hydrogen sulfide (H2S with AzMC) and polysulfides (H2Sn, where n = 2-7, with SSP4) in HEK293 cells. Cells were exposed to inhibitors for up to 5 days in normoxia (21% O2) and hypoxia (5% O2), conditions also known to affect ROS production. Decreasing intracellular glutathione (GSH) with l-buthionine-sulfoximine (BSO) or diethyl maleate (DEM) decreased H2S production for 5 days but did not affect H2Sn. The glutathione reductase inhibitor, auranofin, initially decreased H2S and H2Sn but after two days H2Sn increased over controls. Inhibition of peroxiredoxins with conoidin A decreased H2S and increased H2Sn, whereas the glutathione peroxidase inhibitor, tiopronin, increased H2S. Aminoadipic acid, an inhibitor of cystine uptake did not affect either H2S or H2Sn. In buffer, the glutathione reductase and thioredoxin reductase inhibitor, 2-AAPA, the glutathione peroxidase mimetic, ebselen, and tiopronin variously reacted directly with AzMC and SSP4, reacted with H2S and H2S2, or optically interfered with AzMC or SSP4 fluorescence. Collectively these results show that antioxidant inhibitors, generally known for their ability to increase cellular ROS, have various effects on cellular RSS. These findings suggest that the inhibitors may affect cellular sulfur metabolism pathways that are not related to ROS production and in some instances they may directly affect RSS or the methods used to measure them. They also illustrate the importance of carefully evaluating RSS metabolism when biologically or pharmacologically attempting to manipulate ROS. SN - 1873-4596 UR - https://www.unboundmedicine.com/medline/citation/30790656/Effects_of_inhibiting_antioxidant_pathways_on_cellular_hydrogen_sulfide_and_polysulfide_metabolism_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0891-5849(18)32592-9 DB - PRIME DP - Unbound Medicine ER -