Hydrogen sulfide increases glutathione production and suppresses oxidative stress in mitochondria

Interactions of multiple gas-transducing systems: hallmarks and uncertainties of CO, NO, and H2S gas biology

The diverse physiological actions of the "biologic gases," O2, CO, NO, and H2S, have attracted much interest. Initially viewed as toxic substances, CO, NO, and H2S play important roles as signaling molecules. The multiplicity of gas actions and gas targets and the difficulty in measuring local gas concentrations obscures detailed mechanisms whereby gases exert their actions, and many questions remain unanswered. It is now readily apparent, however, that heme-based proteins play central roles in gas-generation/reception mechanisms and provide a point where multiple gases can interact. In this review, we consider a number of key issues related to "gas biology," including the effective tissue concentrations of these gases and the importance and significance of the physical proximity of gas-producing and gas-receptor/sensors. We also take an integrated approach to the interaction of gases by considering the physiological significance of CO, NO, and H2S on mitochondrial cytochrome c oxidase, a key target and central mediator of mitochondrial respiration. Additionally, we consider the effects of biologic gases on mitochondrial biogenesis and "suspended animation." By evaluating gas-mediated control functions from both in vitro and in vivo perspectives, we hope to elaborate on the complex multiple interactions of O2, NO, CO, and H2S.

Development of hydrogen sulfide-based therapeutics for cardiovascular disease

The physiological role of the gaseous signaling molecule hydrogen sulfide (H(2)S) was first realized in the mid-1990s with the work of Abe and Kimura. Since then, it has become evident that this endogenous gas is extremely important in the homeostasis of the cardiovascular system and the pathogenesis of cardiovascular disease. Several biotechnology companies have developed and are developing H(2)S-based therapeutic compounds, and there are ongoing clinical trials investigating the therapeutic potential of H(2)S. Several organic and chemical compounds that are known H(2)S donors have the potential to be developed into effective H(2)S-based therapeutic agents. This review will provide a historical and current perspective on the role(s) of H(2)S in the cardiovascular system and the current state of development and future outlook of H(2)S-based therapies for cardiovascular disease.

Measurement of extracellular (exofacial) versus intracellular protein thiols

In recent years, the importance of compartmentalization in redox signaling has been realized. A number of specific thiol pools exist both inside and outside the cell, and these thiols are regulated via unique mechanisms and serve specific roles in cell signaling. This chapter covers some of the methodologies available for the interrogation of thiol status in various cellular compartments, with a focus on mitochondrial, cytosolic, and exofacial thiols. Finally, the relevance of these thiols to pathological disease states, in particular cancer, will be discussed. The chapters in the remainder of this volume more than adequately cover the diversity of thiol modifications, describing the specific biochemical nature of these reactions, ranging from S-nitrosation through glutathionylation, to oxidation and beyond. Therefore, this topic will not be further addressed here. Similarly, general methodological considerations are considered to have been dealt with in the remainder of this volume, including requirements for subdued lighting, avoidance of reducing agents and transition metals in media, and rapid sample preparation with adequate control over temperature and pH.

Hydrogen sulfide and ischemia-reperfusion injury

Gasotransmitters are lipid soluble, endogenously produced gaseous signaling molecules that freely permeate the plasma membrane of a cell to directly activate intracellular targets, thus alleviating the need for membrane-bound receptors. The gasotransmitter family consists of three members: nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H(2)S). H(2)S is the latest gasotransmitter to be identified and characterized and like the other members of the gasotransmitter family, H(2)S was historically considered to be a toxic gas and an environmental/occupational hazard. However with the discovery of its presence and enzymatic production in mammalian tissues, H(2)S has gained much attention as a physiological signaling molecule. Also, much like NO and CO, H(2)S's role in ischemia/reperfusion (I/R) injury has recently begun to be elucidated. As such, modulation of endogenous H(2)S and administration of exogenous H(2)S has now been demonstrated to be cytoprotective in various organ systems through diverse signaling mechanisms. This review will provide a detailed description of the role H(2)S plays in different model systems of I/R injury and will also detail some of the mechanisms involved with its cytoprotection.

The expression and activity of cystathionine-γ-lyase and 3-mercaptopyruvate sulfurtransferase in human neoplastic cell lines

The expression and activity of cystathionine γ-lyase (CST) and 3-mercaptopyruvate sulfurtransferase (MPST) were investigated in the human neoplastic cells lines: astrocytoma U373, neuroblastoma SH-SY5Y, melanoma A375, and melanoma WM35. Gene expression analysis demonstrated that the investigated neoplastic cells showed the expression of MPST and what is particularly interesting, the expression of CST. The presence of CST in these cells was confirmed using RT-PCR and western blot analysis. However, in U373 cells, a very low activity of CST was detected. In all the investigated cell lines, the activity of MPST was higher than that of CST, which suggests that in these cells, the main pathway of sulfane sulfur formation is the MPST-catalyzed reaction. RP-HPLC analysis showed a large disparity between the level of cystathionine and GSH in the investigated neoplastic cells. In SH-SY5Y cells, the low level of GSH and low GSH/GSSG ratio corresponded with the highest CST activity. Further investigations could aim at verifying whether the stimulation of CST, at the level of protein or gene expression, could change the proliferation of neoplastic cells.

Hydrogen sulfide: from brain to gut

Three hundred years have passed since the first description of the toxicity of hydrogen sulfide (H(2)S). Three papers in 1989 and 1990 described relatively high concentrations of sulfide in the brain. In 1996 we demonstrated that cystathionine beta-synthase (CBS) is a H(2)S producing enzyme in the brain and that H(2)S enhances the activity of NMDA receptors and facilitates the induction of hippocampal long-term potentiation (LTP), a synaptic model of memory. In the following year, we demonstrated that another H(2)S producing enzyme, cystathionine gamma-lyase is in the thoracic aorta, portal vein, and the ileum, and that H(2)S relaxes these tissues. Based on these observations we proposed H(2)S as a neuromodulator as well as a smooth muscle relaxant. We recently demonstrated that the third H(2)S-producing enzyme, 3-mercaptopyruvate sulfurtransferase (3MST) along with cysteine aminotransferase (CAT) produces H(2)S in the brain as well as in vascular endothelium. Various functions in many tissues have been proposed. H(2)S protects neurons and cardiac muscle from oxidative stress. H(2)S has pro- and anti-inflammatory effects, nociceptive effects, the regulatory function of insulin release, and is even involved in longevity. Recent progress in the studies of physiological functions of H(2)S in neurons and smooth muscle was described.

Mechanisms of angiogenesis: role of hydrogen sulphide

1. Hydrogen sulphide (H(2)S) has recently been recognized as a gasotransmitter that regulates angiogenesis in vitro and in vivo under physiological and ischaemic conditions. 2. In the present review, the mechanisms underlying angiogenesis are summarized briefly and the most recent progress in H(2)S-induced angiogenesis in vivo and in vitro is described. The anti-angiogenic effects of garlic extracts, which may serve as substrates for H(2)S-generating enzymes in vivo, are also discussed. 3. Hydrogen sulphide increases cell growth, migration and the formation of tube-like structures in cultured endothelial cells. These effects are dependent on activation of the phosphatidylinositol 3-kinase-Akt-survivin signalling pathway. Neovascularization in vivo has also been demonstrated to be promoted in the mouse Matrigel plug assay, as well as in chicken chorioallantoic membranes. In a rat unilateral hindlimb ischaemic model, treatment with sodium hydrosulphide (NaHS), an H(2)S donor, promotes significant angiogenesis and improves regional blood flow. These effects may be mediated by interactions between upregulated vascular endothelial growth factor (VEGF) in skeletal muscle cells and VEGF receptor 2 and the downstream signalling element Akt in vascular endothelial cells. However, H(2)S does not exhibit a pro-angiogenic effect at a high concentrations/doses. 4. Based on the studies reviewed in the present article, we assume that, at physiologically relevant doses/concentrations, H(2)S/HS(-) promote angiogenesis at least partly via the VEGF signalling pathway. At high doses, H(2)S/HS(-) may act on additional cellular targets to evoke mechanisms that counteract the pro-angiogenic pathways. More studies need to be performed analysing the general interactions between H(2)S/HS(-) and other molecules, including other gasotransmitters, such as nitric oxide and carbon monoxide (CO).