title: Regulation of mitochondrial bioenergetic function by hydrogen sulfide. Part I. Biochemical and physiological mechanisms.
abstract: Until recently, hydrogen sulfide (H2 S) was exclusively viewed a toxic gas and an environmental hazard, with its toxicity primarily attributed to the inhibition of mitochondrial Complex IV, resulting in a shutdown of mitochondrial electron transport and cellular ATP generation. Work over the last decade established multiple biological regulatory roles of H2 S, as an endogenous gaseous transmitter. H2 S is produced by cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). In striking contrast to its inhibitory effect on Complex IV, recent studies showed that at lower concentrations, H2 S serves as a stimulator of electron transport in mammalian cells, by acting as a mitochondrial electron donor. Endogenous H2 S, produced by mitochondrially localized 3-MST, supports basal, physiological cellular bioenergetic functions; the activity of this metabolic support declines with physiological aging. In specialized conditions (calcium overload in vascular smooth muscle, colon cancer cells), CSE and CBS can also associate with the mitochondria; H2 S produced by these enzymes, serves as an endogenous stimulator of cellular bioenergetics. The current article overviews the biochemical mechanisms underlying the stimulatory and inhibitory effects of H2 S on mitochondrial function and cellular bioenergetics and discusses the implication of these processes for normal cellular physiology. The relevance of H2 S biology is also discussed in the context of colonic epithelial cell physiology: colonocytes are exposed to high levels of sulfide produced by enteric bacteria, and serve as a metabolic barrier to limit their entry into the mammalian host, while, at the same time, utilizing it as a metabolic 'fuel'.
authors.affiliation: Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Csaba
authors.initials: C
authors.lastname: Szabo
authors.forename: Céline
authors.initials: C
authors.lastname: Ransy
authors.forename: Katalin
authors.initials: K
authors.lastname: Módis
authors.forename: Mireille
authors.initials: M
authors.lastname: Andriamihaja
authors.forename: Baptiste
authors.initials: B
authors.lastname: Murghes
authors.forename: Ciro
authors.initials: C
authors.lastname: Coletta
authors.forename: Gabor
authors.initials: G
authors.lastname: Olah
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yanagi
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bouillaud
mesh_terms: D000818:Animals; D019069:Cell Respiration / Q000502:physiology; D003106:Colon / Q000502:physiology; D004579:Electron Transport / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D004847:Epithelial Cells / Q000502:physiology; D064426:Gasotransmitters / Q000378:metabolism / Q000502:physiology* / Q000633:toxicity; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism* / Q000633:toxicity; D008928:Mitochondria / Q000378:metabolism* / Q000502:physiology*; D008954:Models, Biological
chemical_list: D064426:Gasotransmitters; D006862:Hydrogen Sulfide
keywords: 3-mercaptopyruvate sulfurtransferase; bioenergetics; blood vessels; cysteine; cytochrome c oxidase; free radicals; gasotransmitters; mitochondrial electron transport; nitric oxide; superoxide