Intramitochondrial hydrogen sulfide production by 3‐mercaptopyruvate sulfurtransferase maintains mitochondrial electron flow and supports cellular bioenergetics

Abstract

It is well established that exposure of mammalian cells to hydrogen sulfide (H(2)S) suppresses mitochondrial function by inhibiting cytochrome-c oxidase (CcOX; complex IV). However, recent experimental data show that administration of H(2)S to mammalian cells can serve as an electron donor and inorganic source of energy. The aim of our study was to investigate the role of endogenously produced H(2)S in the regulation of mitochondrial electron transport and oxidative phosphorylation in isolated liver mitochondria and in the cultured murine hepatoma cell line Hepa1c1c7. Low concentrations of H(2)S (0.1-1 μM) elicited a significant increase in mitochondrial function, while higher concentrations of H(2)S (3-30 μM) were inhibitory. The positive bioenergetic effect of H(2)S required a basal activity of the Krebs cycle and was most pronounced at intermediate concentrations of succinate. 3-mercaptopyruvate (3-MP), the substrate of the mitochondrial enzyme 3-mercaptopyruvate sulfurtransferase (3-MST) stimulated mitochondrial H(2)S production and enhanced mitochondrial electron transport and cellular bioenergetics at low concentrations (10-100 nM), while at higher concentrations, it inhibited cellular bioenergetics. SiRNA silencing of 3-MST reduced basal bioenergetic parameters and prevented the stimulating effect of 3-MP on mitochondrial bioenergetics. Silencing of sulfide quinone oxidoreductase (SQR) also reduced basal and 3-MP-stimulated bioenergetic parameters. We conclude that an endogenous intramitochondrial H(2)S-producing pathway, governed by 3-MST, complements and balances the bioenergetic role of Krebs cycle-derived electron donors. This pathway may serve a physiological role in the maintenance of mitochondrial electron transport and cellular bioenergetics.

Regulation of Vascular Tone, Angiogenesis and Cellular Bioenergetics by the 3-Mercaptopyruvate Sulfurtransferase/H2S Pathway: Functional Impairment by Hyperglycemia and Restoration by dl-α-Lipoic Acid

“…3-MP (10 μmol/L) stimulated mitochondrial function, consistent with our recent studies (20,38), showing that mitochondria generate H 2 S when incubated with 3-MP and that the resulting H 2 S gives electrons to the mitochondria at complex II and stimulates mitochondrial electron transport and cellular bioenergetics. The 3-MP-elicited stimulatory effect on mitochondrial respiration was reduced in mitochondria from STZ-diabetic rats by approximately 40% (Figure 7), in line with prior findings (20) demonstrating that oxidative stress attenuates the catalytic activity of 3-MST and of the H 2 S-associated bioenergetic responses.…”

“…Although the presence of 3-MST and the metabolism of 3-MP by 3-MST in various tissues has been known for over three decades (54), the production of H 2 S by this pathway has only been realized in the last few years. There are now several reports demonstrating 3-MP/3-MST induced H 2 S production in the central and peripheral nervous system (55,56) and in the vascular endothelium (17), as well as in various other cells and tissues (20,38,43). The oxidative-stresssensitive nature of 3-MST (57,58) and the functional consequence of this property (in terms of reduced H 2 S production and impaired cellular bioenergetics) (20) have also been demonstrated in recent years.…”

“…The XF24 Extracellular Flux Analyzer (Seahorse Biosciences, North Billerica, MA, USA) was used to measure mitochondrial bioenergetic function, as described (38). Mitochondria from rat livers (control, diabetic, either treated with vehicle or with LA, as described above) were isolated by differential centrifugation and used for bioenergetic analysis.…”

“…We have recently demonstrated that 3-MST activity is inhibited by oxidative stress in vitro and speculated that this may exert adverse effects on cellular homeostasis (20,21). Given the importance of H 2 S as a vasorelaxant (22)(23)(24)(25)(26)(27)(28)(29), proangiogenic agent (27,(30)(31)(32)(33)(34)(35)(36) and mitochondrial/bioenergetic modulator (20,21,35,(37)(38)(39)(40)(41)(42), here we examined whether the 3-MST/H 2 S system plays physiological regulatory roles in endothelial cells. Next, we examined whether a dysfunction of the 3-MST/H 2 S system develops in hyperglycemia/diabetes and tested whether this dysfunction can be corrected by DL-α-lipoic acid (LA), a known antioxidant and 3-MST cofactor (43)(44)(45).…”

H2S in the Vasculature: Controversy of Mechanisms in Physiology, Pathology and Beyond

“…3-MST/CAT is localized in thoracic aorta ECs and produces H 2 S [13]; however, a vascular effect of 3-MST/CATderived H 2 S is unknown. Endogenous intra mitochondrial 3-MSTderived H 2 S has been shown to protect mitochondrial function/ metabolism [14].…”