Cysteine Aminotransferase Research Articles

Chemistry of Hydrogen Sulfide-Pathological and Physiological Functions in Mammalian Cells.

Hydrogen sulfide (H2S) was recognized as a gaseous signaling molecule, similar to nitric oxide (-NO) and carbon monoxide (CO). The aim of this review is to provide an overview of the formation of hydrogen sulfide (H2S) in the human body. H2S is synthesized by enzymatic processes involving cysteine and several enzymes, including cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), cysteine aminotransferase (CAT), 3-mercaptopyruvate sulfurtransferase (3MST) and D-amino acid oxidase (DAO). The physiological and pathological effects of hydrogen sulfide (H2S) on various systems in the human body have led to extensive research efforts to develop appropriate methods to deliver H2S under conditions that mimic physiological settings and respond to various stimuli. These functions span a wide spectrum, ranging from effects on the endocrine system and cellular lifespan to protection of liver and kidney function. The exact physiological and hazardous thresholds of hydrogen sulfide (H2S) in the human body are currently not well understood and need to be researched in depth. This article provides an overview of the physiological significance of H2S in the human body. It highlights the various sources of H2S production in different situations and examines existing techniques for detecting this gas.

Stimulation of the endogenous hydrogen sulfide synthesis restores constitutive nitric oxide synthesis and endothelium-dependent vasodilation in old rats

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Hydrogen sulfide (H2S) is a gas transmitter of endogenous origin, which has an important regulatory function in the human body. Endogenous H2S is synthesized by three enzymes, cistationine-β-synthase (CBS), cistationine-γ-liase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MTS), which is coupled to the activity of cysteine aminotransferase (CAT). CAT, CBS, and CSE are pyridoxal-5- phosphate (PLP)-dependent enzymes. It is known that with age the exchange of hydrogen sulfide is disturbed against the background of increasing oxidative and nitrosative stress. At the same time there is a decrease of constitutive synthesis of nitric oxide (NO). Recent studies show that hydrogen sulfide closely interacts with the NO system. Activation of H2S biosynthesis and restoration of its pools in tissues of old animals may be a promising direction of cardiovascular disease prevention. The aim of the current work was to study the effect of H2S-synthesizing enzymes cofactor pyridoxal-5-phosphate (PLP) on the endothelium-dependent relaxation of smooth muscle vessels in old rats, as well as the H2S content and cNOS activity in aortic tissues. Methods Old rats (22-24 months old) were PLP administered per os in dose of 0,7 mg per kg daily for 2 weeks.The content of hydrogen sulfide, activity of cNOS and iNOS was measured in aortic tissues.Vascular reactions were determined in experiments on isolated aortic strips. To clarify the role of either NO or H2S in the endothelium-dependent vasorelaxation, N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (Sigma, USA, 27 mg/kg) or O-carboxymethylhydroxylamine (O-CMH) (50 mg/kg) (Sigma, USA) was injected intraperitoneally 30 min before sacrificing. Results We showed that the H2S content was 1.6 times lower in old rat aorta compared to adult ones. PLP administration for 2 weeks induced a significant increase of H2S content in aortic tissue of old rats (P<0.05). It was found that with aging, the activity of cNOS decreases by 3 times, and the stimulation of endogenous Н2S leads to an increase in the activity of this enzyme in the aortic tissues by 2.1 times as compared with those in old animals. At the same time, the activity of the iNOS enzyme with aging increases by 3.8 times, and after the introduction of PLP, it decreases almost halved. Also shown, that PLP significantly improved endothelium-dependent aortic smooth muscle relaxation in old rats. The amplitude of acetylcholine-induced relaxation which was significantly reduced in old rats was increased more than 2.5-fold. This effect was reversed by inhibitors of NO-synthase and 3-mercaptopyruvate sulfurtransferase indicating the involvement of NO and H2S in the improved endothelium-dependent vascular relaxation. Conclusions Thus, H2S acts as a regulator of the NO system that increases cNOS activity and NO synthesis in aortic tissue, which improves endothelium-dependent relaxation of aortic smooth muscle in aged rats.

Hydrogen sulfide has a role as an endogenous relaxation factor in the rat prostate

ABSTRACT Introduction Hydrogen sulfide (H2S) is the third endogenous gasotransmitter besides carbon monoxide and nitric oxide, and has a wide range of physiological functions such as neuromodulation, vasorelaxation and cytoprotection. Although in human prostate cancer cells, NaHS (a H2S donor) treatment was reported to inhibit proliferation and to elevate secretory function, physiological functions of H2S in the prostate tissue had not been investigated yet. Endogenous H2S is biosynthesized from L-cysteine by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). In addition, 3-mercaptopyruvate sulfurtransferase (MPST) synthesizes H2S from 3-mercaptopyruvate (3MP), which is produced from L-cysteine by cysteine aminotransferase (CAT) (CAT/MPST pathway). Recently, a new pathway for endogenous H2S biosynthesis is reported; D-cysteine is metabolized by D-amino acid oxidase (DAO) to 3MP, which is a substrate for MPST to synthesize H2S. Objective We investigated (1) tissue distribution of CBS, CSE, MPST, CAT and DAO, (2) endogenous H2S levels, and (3) effects of NaHS on contractility in the rat prostate. Methods Dorsolateral and ventral prostate (PR-D and PR-V), liver and cerebellum (L and C) were prepared from male Wistar rats (300-400 g) sacrificed with an overdose of sodium pentobarbital (80 mg/kg, ip). (1) Tissue distributions of 5 enzymes were investigated by real-time PCR, western blot and immunohistochemistry. L and C were used for positive controls. (2) H2S contents in the prostate tissues were measured by methylene blue method. (3) By using 1 x 5 mm strips of the prostate tissues, effects of NaHS (1 x 10-9 to 3 x 10-4 M) were evaluated on pre-contracted prostate strips by noradrenaline (10-5 M). Prostate strips were pretreated with propranolol (10-6 M) 30 min before the pre-contraction. Results (1) CBS, MPST and CAT were detected in the prostate. Expression levels of CBS in the PR-D were lower than those in the PR-V, and the levels of MPST in the PR-D were higher than those in the PR-V. In expression levels of CAT, there was no significant difference between two prostate tissues. On the other hand, CSE or DAO was not detected in these tissues. Immunoreactvities of these enzymes were mainly detected in the prostate glandular epithelium. (2) H2S was detected in the prostate tissues. (3) NaHS dose-dependently induced relaxation of pre-contracted PR-D and PR-V strips. There were no significant differences of the EC50 values or relaxation rate against the pre-contractions between two prostate tissues. Conclusion H2S synthesized by CBS- and CAT/MPST-mediated pathways has a role as an endogenous relaxation factor in the rat prostate. Therefore, endogenous H2S might open new avenues of therapeutic interventions for benign prostatic hyperplasia. Disclosure Work supported by industry: no.

Modulation of Human Hydrogen Sulfide Metabolism by Micronutrients, Preliminary Data.

Background:Hydrogen sulfide (H2S) is a pivotal gasotransmitter networking with nitric oxide (NO) and carbon monoxide (CO) to regulate basic homeostatic functions. It is released by the alternative pathways of transulfuration by the enzymes Cystathionine Beta Synthase (CBS) and Cystathionine Gamma Lyase (CSE), and by Cysteine AminoTransferase (CAT)/ 3-Mercaptopyruvate Sulfur Transferase (3MPST). A non-enzymatic, intravascular release is also in place. We retrospectively investigated the possibility to modulate the endogenous H2S release and signaling in humans by a dietary manipulation with supplemented micronutrients (L-cystine, Taurine and pyridoxal 5-phopsphate/P5P).Methods:Patients referring for antiaging purposes underwent a 10-day supplementation. Blood was collected at baseline and after treatment and the metabolome was investigated by mass spectrometry to monitor the changes in the metabolites reporting on H2S metabolism and related pathways.Results:Data were available from 6 middle aged subjects (2 women). Micronutrients increased 3-mercaptopyruvate (P = .03), reporting on the activity of CAT that provides the substrate for H2S release within mitochondria by 3MPST, decreased lanthionine (P = .024), reporting the release of H2S from CBS, and had no significant effect of H2S release from CSE. This is compatible with a homeostatic balancing. We also recorded a strong increase of reporters of H2S-induced pathways including 5-MethylTHF (P = .001) and SAME (P = .022), reporting on methylation capacity, and of BH4 (P = .021) and BH2 (P = .028) reporting on nitric oxide metabolism. These activations may be explained by the concomitant induction of non-enzymatic release of H2S.Conclusions:Although the current evidences are weak and will need to be confirmed, the effect of micronutrients was compatible with an increase of the H2S endogenous release and signaling within the control of homeostatic mechanisms, further endorsing the role of feeding in health and disease. These effects might result in a H2S boosting effect in case of defective activity of pathologic origin, which should be checked in duly designed clinical trials.

Cysteine Boosts Fitness Under Hypoxia-Mimicked Conditions in Ovarian Cancer by Metabolic Reprogramming.

Among gynecologic malignancies, ovarian cancer is the third most prevalent and the most common cause of death, especially due to diagnosis at an advanced stage together with resistance to therapy. As a solid tumor grows, cancer cells in the microenvironment are exposed to regions of hypoxia, a selective pressure prompting tumor progression and chemoresistance. We have previously shown that cysteine contributes to the adaptation to this hypoxic microenvironment, but the mechanisms by which cysteine protects ovarian cancer cells from hypoxia-induced death are still to be unveiled. Herein, we hypothesized that cysteine contribution relies on cellular metabolism reprogramming and energy production, being cysteine itself a metabolic source. Our results strongly supported a role of xCT symporter in energy production that requires cysteine metabolism instead of hydrogen sulfide (H2S) per se. Cysteine degradation depends on the action of the H2S-synthesizing enzymes cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and/or 3-mercaptopyruvate sulfurtransferase (MpST; together with cysteine aminotransferase, CAT). In normoxia, CBS and CSE inhibition had a mild impact on cysteine-sustained ATP production, pointing out the relevance of CAT + MpST pathway. However, in hypoxia, the concomitant inhibition of CBS and CSE had a stronger impact on ATP synthesis, thus also supporting a role of their hydrogen sulfide and/or cysteine persulfide-synthesizing activity in this stressful condition. However, the relative contributions of each of these enzymes (CBS/CSE/MpST) on cysteine-derived ATP synthesis under hypoxia remains unclear, due to the lack of specific inhibitors. Strikingly, NMR analysis strongly supported a role of cysteine in the whole cellular metabolism rewiring under hypoxia. Additionally, the use of cysteine to supply biosynthesis and bioenergetics was reinforced, bringing cysteine to the plateau of a main carbon sources in cancer. Collectively, this work supports that sulfur and carbon metabolism reprogramming underlies the adaptation to hypoxic microenvironment promoted by cysteine in ovarian cancer.

Age-related differences in responses to hydrogen sulfide in the bladder of spontaneously hypertensive rats.

To investigate whether a response to hydrogen sulfide donors (GYY4137 and sodium hydrosulfide) and the endogenous hydrogen sulfide system (hydrogen sulfide level and expression of cysteine aminotransferase, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase) in the spontaneously hypertensive rat bladder differ with age, we compared the responses of hydrogen sulfide donors to micturition and bladder relaxation, and the endogenous hydrogen sulfide system in the bladder of 18-week versus 12-week-old spontaneously hypertensive rats. GYY4137 was intravesically administered and cystometry was performed in anesthetized rats. The responses of sodium hydrosulfide were evaluated in carbachol-mediated precontracted bladder strips. Bladder hydrogen sulfide levels and expression levels of each enzyme were investigated using the methylene blue method and Western blotting, respectively. GYY4137 treatment significantly prolonged intercontraction intervals only in 12-week-old rats. Sodium hydrosulfide-induced bladder relaxation was significantly attenuated in the strips of 18-week-old rats compared with that in 12-week-old rats. In the bladder dome, significant increases in hydrogen sulfide levels and in the expression of cystathionine β-synthase, 3-mercaptopyruvate sulfurtransferase, and cysteine aminotransferase were observed in 18-week-old rats compared with 12-week-old rats. However, cystathionine γ-lyase bands were not detected in bladder tissues of either group. Bladder relaxation induced by hydrogen sulfide may be attenuated in spontaneously hypertensive rats in an age-dependent manner.

Cysteine Aminotransferase (CAT): A Pivotal Sponsor in Metabolic Remodeling and an Ally of 3-Mercaptopyruvate Sulfurtransferase (MST) in Cancer.

Metabolic remodeling is a critical skill of malignant cells, allowing their survival and spread. The metabolic dynamics and adaptation capacity of cancer cells allow them to escape from damaging stimuli, including breakage or cross-links in DNA strands and increased reactive oxygen species (ROS) levels, promoting resistance to currently available therapies, such as alkylating or oxidative agents. Therefore, it is essential to understand how metabolic pathways and the corresponding enzymatic systems can impact on tumor behavior. Cysteine aminotransferase (CAT) per se, as well as a component of the CAT: 3-mercaptopyruvate sulfurtransferase (MST) axis, is pivotal for this metabolic rewiring, constituting a central mechanism in amino acid metabolism and fulfilling the metabolic needs of cancer cells, thereby supplying other different pathways. In this review, we explore the current state-of-art on CAT function and its role on cancer cell metabolic rewiring as MST partner, and its relevance in cancer cells’ fitness.

Hydrogen Sulfide and Endoplasmic Reticulum Stress: A Potential Therapeutic Target for Central Nervous System Degeneration Diseases.

There are three members of the endogenous gas transmitter family. The first two are nitric oxide and carbon monoxide, and the third newly added member is hydrogen sulfide (H2S). They all have similar functions: relaxing blood vessels, smoothing muscles, and getting involved in the regulation of neuronal excitation, learning, and memory. The cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfur transferase acts together with cysteine aminotransferase (3-MST/CAT), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfur transferase with D-amino acid oxidase (3-MST/DAO) pathways are involved in the enzymatic production of H2S. More and more researches focus on the role of H2S in the central nervous system (CNS), and H2S plays a significant function in neuroprotection processes, regulating the function of the nervous system as a signaling molecule in the CNS. Endoplasmic reticulum stress (ERS) and protein misfolding in its mechanism are related to neurodegenerative diseases. H2S exhibits a wide variety of cytoprotective and physiological functions in the CNS degenerative diseases by regulating ERS. This review summarized on the neuroprotective effect of H2S for ERS played in several CNS diseases including Alzheimer’s disease, Parkinson’s disease, and depression disorder, and discussed the corresponding possible signaling pathways or mechanisms as well.

MP28-10 COMPARISON OF THE HYDROGEN SULFIDE-INDUCED RELAXATION OF THE BLADDER BETWEEN HYPERTENSIVE AND NORMOTENSIVE RATS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology I (MP28)1 Apr 2020MP28-10 COMPARISON OF THE HYDROGEN SULFIDE-INDUCED RELAXATION OF THE BLADDER BETWEEN HYPERTENSIVE AND NORMOTENSIVE RATS Suo Zou*, Takahiro Shimizu, Shogo Shimizu, Youichirou Higashi, Takaaki Aratake, Masaki Yamamoto, Tomoya Hamada, Yoshiki Nagao, Masashi Honda, and Motoaki Saito Suo Zou*Suo Zou* More articles by this author , Takahiro ShimizuTakahiro Shimizu More articles by this author , Shogo ShimizuShogo Shimizu More articles by this author , Youichirou HigashiYouichirou Higashi More articles by this author , Takaaki AratakeTakaaki Aratake More articles by this author , Masaki YamamotoMasaki Yamamoto More articles by this author , Tomoya HamadaTomoya Hamada More articles by this author , Yoshiki NagaoYoshiki Nagao More articles by this author , Masashi HondaMasashi Honda More articles by this author , and Motoaki SaitoMotoaki Saito More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000867.010AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: We recently reported that hydrogen sulfide (H2S), an endogenous gasotransmitter, is a possible relaxation factor in the rat bladder. Because it has shown that bladder dysfunctions can be developed by chronic hypertension in spontaneously hypertensive rats (SHRs), we compared effects of NaHS and GYY4137 (H2S donors) on the bladder contractility and the micturition reflex, and the endogenous H2S system in the bladder between SHRs and normotensive Wistar rats (Wistars). METHODS: Eighteen-week-old male SHRs and Wistars were used. (1) Under urethane (0.8 g/kg, ip) anesthesia, a catheter was inserted into the bladder to instill reagents (2.4 ml/h) and to measure intravesical pressure. After detecting 4-5 micturition reflexes induced by saline instillation, GYY4137 solution (10-8, 10-7 and 10-6 M) or vehicle was instilled. (2) Bladder dome and trigone (BL-D and BL-T) were prepared from both rats. Effects of NaHS (1×10-8 to 3×10-4 M) were evaluated on carbachol (10-5 M)-induced pre-contracted bladder strips. H2S contents were measured by the methylene blue method. Expression levels of enzymes related to H2S biosynthesis [3-mercaptopyruvate sulfurtransferase (MPST), cysteine aminotransferase (CAT) and cystathionine β-synthase (CBS)] were examined by western blotting. RESULTS: (1) GYY4137 significantly prolonged intercontraction intervals compared to the vehicle-treated group in Wistars, but not in SHRs (Table 1). (2) NaHS-induced relaxation on pre-contracted BL-D and BL-T strips was significantly attenuated in SHRs compared to Wistars (Table 2). The H2S content in the bladder of SHRs was significantly higher than that of Wistars (Fig. C). The expression levels of MPST, but not CAT or CBS, in the SHR bladder were significantly higher than those in the Wistar bladder (Fig. D). CONCLUSIONS: H2S-induced bladder relaxation in SHRs is attenuated, which might be a cause of hypertension-mediated development of bladder dysfunctions. To compensate the less responsiveness, endogenous H2S levels might be increased in the SHR bladder. Therefore, the endogenous H2S system might be a new drug candidate for the treatment of hypertension-mediated bladder dysfunctions. Source of Funding: JSPS KAKENHI (#15K15583), GSK Japan Research Grant 2017 © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e423-e423 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Suo Zou* More articles by this author Takahiro Shimizu More articles by this author Shogo Shimizu More articles by this author Youichirou Higashi More articles by this author Takaaki Aratake More articles by this author Masaki Yamamoto More articles by this author Tomoya Hamada More articles by this author Yoshiki Nagao More articles by this author Masashi Honda More articles by this author Motoaki Saito More articles by this author Expand All Advertisement PDF downloadLoading ...

Hydrogen sulfide formation in experimental model of acute pancreatitis.

Acute pancreatitis (AP) is a disease defined as acute or chronic inflammatory process of the pancreas characterized by premature activation of digestive enzymes within the pancreatic acinar cells and causing pancreatic auto-digestion. In mammalian tissues, H2S is synthesized endogenously from L-cysteine in regulated enzymatic pathways catalyzed by pyridoxal phosphate-dependent enzymes: cystathionine beta - synthase (CBS), gamma - cystathionase (CTH) and cysteine aminotransferase (CAT) coupled with 3-mercaptopyruvate sulfurtransferase (MPST). In the mitochondria, hydrogen sulfide is oxidized to sulfite, which is then converted to thiosulfate (sulfane sulfur-containing compound) by thiosulfate sulfurtransferase (rhodanese; TST). The activity and the expression of CBS, CTH, MPST, and TST have been determined in vivo in pancreas of control rats, rats with acute pancreatitis and sham group. Levels of low-molecular sulfur compounds such as reduced and oxidized glutathione, cysteine, cystine and cystathionine were also determined. The study showed the significant role of MPST in H2S metabolism in pancreas. Stress caused by the surgery (sham group) and AP cause a decrease in H2S production associated with a decrease of MPST activity and expression. Markedly higher level of cysteine in the AP pancreas may be caused by a reduced rate of cysteine consumption in reaction catalyzed by MPST but it can also be a sign of the processes of proteolysis occurring in the changed tissue.

Surgical Preparation Reduces Hydrogen Sulfide Released from Human Saphenous Veins in Coronary Artery Bypass Grafting.

The long-term patency rate of saphenous vein (SV) grafts is poor compared to arterial grafts. To investigate the effects of surgical preparation (distention) of SV on hydrogen sulfide (H2S) released from the endothelium, human SV segments were harvested from 43 patients during coronary artery bypass surgery (CABG). Acetylcholine (ACh) induced relaxation that was inhibited by NG-nitro-L-arginine + indomethacin and cysteine aminotransferase inhibitor aminooxyacetic acid in the normal SV. In contrast, ACh did not evoke relaxation in the distended SV (DSV). The concentration of H2S quantified by methylene blue assay in DSV was significantly lower than that in control. Transmission electron microscope and immunohistochemistry studies showed that the preparation destroyed the endothelium, smooth muscle, organelle, and vasa vasorum. We conclude that surgical preparation injures the endothelium and smooth muscle of the SV grafts and reduces H2S release from SV. These effects may contribute to the poor long-term patency of the SV graft.

Hydrogen sulfide-induced relaxation of the bladder is attenuated in spontaneously hypertensive rats.

To compare hydrogen sulfide (H2S)-induced relaxation on the bladder between normotensive and spontaneously hypertensive rat (SHR), we evaluated the effects of H2S donors (GYY4137 and NaHS) on the micturition reflex and on the contractility of bladder tissues. We also investigated the content of H2S and the expression levels of enzymes related to H2S biosynthesis [cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (MPST), and cysteine aminotransferase (CAT)] in the bladder. Eighteen-week-old male normotensive Wistar rats and SHRs were used. Under urethane anesthesia, the effects of intravesically instilled GYY4137 (10-8, 10-7 and 10-6 M) on the micturition reflex were evaluated by cystometry. The effects of NaHS (1 × 10-8-3 × 10-4 M) were evaluated on carbachol (10-5 M)-induced pre-contracted bladder strips. Tissue H2S content was measured by the methylene blue method. The expression levels of these enzymes were investigated by Western blot. GYY4137 significantly prolonged intercontraction intervals in Wistar rats, but not in SHRs. NaHS-induced relaxation on pre-contracted bladder strips was significantly attenuated in SHRs compared with Wistar rats. The H2S content in the bladder of SHRs was significantly higher than that of Wistar rats. CBS, MPST and CAT were detected in the bladder of Wistar rats and SHRs. The expression levels of MPST in the SHR bladder were significantly higher than those in the Wistar rat bladder. H2S-induced bladder relaxation in SHRs is impaired, thereby resulting in a compensatory increase of the H2S content in the SHR bladder.

S-3-Carboxypropyl-l-cysteine specifically inhibits cystathionine γ-lyase–dependent hydrogen sulfide synthesis

Hydrogen sulfide (H2S) is a gaseous signaling molecule, which modulates a wide range of mammalian physiological processes. Cystathionine γ-lyase (CSE) catalyzes H2S synthesis and is a potential target for modulating H2S levels under pathophysiological conditions. CSE is inhibited by propargylglycine (PPG), a widely used mechanism-based inhibitor. In this study, we report that inhibition of H2S synthesis from cysteine, but not the canonical cystathionine cleavage reaction catalyzed by CSE in vitro, is sensitive to preincubation of the enzyme with PPG. In contrast, the efficacy of S-3-carboxpropyl-l-cysteine (CPC) a new inhibitor described herein, was not dependent on the order of substrate/inhibitor addition. We observed that CPC inhibited the γ-elimination reaction of cystathionine and H2S synthesis from cysteine by human CSE with Ki values of 50 ± 3 and 180 ± 15 μm, respectively. We noted that CPC spared the other enzymes involved either directly (cystathionine β-synthase and mercaptopyruvate sulfurtransferase) or indirectly (cysteine aminotransferase) in H2S biogenesis. CPC also targeted CSE in cultured cells, inhibiting transsulfuration flux by 80-90%, as monitored by the transfer of radiolabel from [35S]methionine to GSH. The 2.5 Å resolution crystal structure of human CSE in complex with the CPC-derived aminoacrylate intermediate provided a structural framework for the molecular basis of its inhibitory effect. In summary, our study reveals a previously unknown confounding effect of PPG, widely used to inhibit CSE-dependent H2S synthesis, and reports on an alternative inhibitor, CPC, which could be used as a scaffold to develop more potent H2S biogenesis inhibitors.

Hydrogen sulfide-mediated endothelial function and the interaction with eNOS and PDE5A activity in human internal mammary arteries.

ObjectiveTo investigate the role of hydrogen sulfide (H2S) in human internal mammary arteries (IMA) and its interaction with endothelial nitric oxide synthase (eNOS) and phosphodiesterase (PDE)5A activity.MethodsHuman IMA segments from patients undergoing coronary artery bypass grafting (CABG) were studied by myography for acetylcholine and sodium hydrosulfide (NaHS)-induced relaxation. Locations of 3-mercaptopyruvate sulfurtransferase (3-MPST) and cysteine aminotransferase (CAT) were examined immunohistochemically. Levels of H2S, eNOS, phosphorylated-eNOSser1177, and PDE5A were measured.ResultsIn IMA segments from 47 patients, acetylcholine-induced relaxation (resistant to NG-nitro-L-arginine and indomethacin) was significantly attenuated by aminooxyacetic acid or L-aspartate (CAT inhibitors), iberiotoxin (large-conductance calcium-activated K+ channel blocker), TRAM-34 plus apamin (intermediate- and small-conductance Ca2+-activated K+ channel blockers) or glibenclamide (ATP-sensitive K+ channel blocker). 3-MPST and mitochondrial CAT were found in endothelial and smooth muscle cells while cytosolic CAT was located only in endothelial cells. Acetylcholine significantly increased the H2S levels. The H2S donor, NaHS, increased eNOS phosphorylation and down-regulated PDE5A.ConclusionsHuman conduit artery endothelium releases H2S under basal and stimulated conditions, involving the 3-MPST/CAT pathway, eNOS phosphorylation, PDE5A activity, and potassium channels. These findings may provide new therapeutic targets for treating vasospasm in CABG grafts and facilitate the development of new vasodilator drugs.

Synthesis, Metabolism, and Signaling Mechanisms of Hydrogen Sulfide: An Overview.

In addition to nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H2S) has recently emerged as the novel gasotransmitter involved in the regulation of the nervous system, cardiovascular functions, inflammatory response, gastrointestinal system, and renal function. H2S is synthesized from L-cysteine and/or L-homocysteine by cystathionine β-synthase, cystathionine γ-lyase, and cysteine aminotransferase together with 3-mercaptopyruvate sulfurtransferase. In addition, H2S is enzymatically metabolized in mitochondria by sulfide:quinone oxidoreductase, persulfide dioxygenase, and sulfite oxidase to thiosulfate, sulfite, and sulfate which enables to regulate its level by factors such as oxygen pressure, mitochondria density, or efficacy of mitochondrial electron transport. H2S modifies protein structure and function through the so-called sulfuration or persulfidation, that is, conversion of cysteine thiol (-SH) to persulfide (-SSH) groups. This, as well as other signaling mechanisms, is partially mediated by more oxidized H2S-derived species, polysulfides (H2Sn). In addition, H2S is able to react with reactive oxygen and nitrogen species to form other signaling molecules such as thionitrous acid (HSNO), nitrosopersulfide (SSNO-), and nitroxyl (HNO). All H2S-synthesizing enzymes are expressed in the vascular wall, and H2S has been demonstrated to regulate vascular tone, endothelial barrier permeability, angiogenesis, vascular smooth muscle cell proliferation and apoptosis, and inflammatory reaction. H2S-modifying therapies are promising approach for diseases such as arterial hypertension, diabetic angiopathy, and atherosclerosis.

The production and role of hydrogen sulfide and hydrogen polysulfides in mammalian cells

Accumulating evidence shows that hydrogen sulfide (H2S) has physiological functions in various tissues and organs. It includes regulation of neuronal activity, vascular tension, a release of insulin, and protection of the heart, kidney, and brain from ischemic insult. H2S is produced from L-cysteine by pyridoxal 5'-phosphate (PLP)-dependent enzymes, cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). 3-Mercaptopyruvate sulfurtransferase (3MST) is the third H2S-producing enzyme. 3-Mercaptopyruvate (3MP) is provided from L-cysteine and α-ketoglutarate by a PLP-dependent cysteine aminotransferase (CAT). An additional pathway for the production of H2S from D-cysteine involving 3MST and D-amino acid oxidase (DAO) has been identified. Recently, hydrogen polysulfides (H2Sn), which are oxidized forms of H2S, have been found to stimulate transient receptor potential ankyrin1 (TRPA1) channel, much more potently than H2S. H2Sn is produced from 3MP by 3MST. In addition to the enzymatic production, the interaction between H2S and nitric oxide (NO), another gaseous signaling molecule, also generates H2Sn. These observations provide new insight into the production of these molecules and their mechanisms of physiological functions.

Possible role of hydrogen sulfide as an endogenous relaxation factor in the rat bladder and prostate.

To clarify the roles of hydrogen sulfide (H2 S), an endogenous gasotransmitter, in the rat bladder and prostate, we investigated the distribution of enzymes related to H2 S biosynthesis (cystathionine β-synthase [CBS], cystathionine γ-lyase [CSE], 3-mercaptopyruvate sulfurtransferase [MPST], cysteine aminotransferase [CAT], and D-amino acid oxidase [DAO]) and the content of H2 S. We also investigated the effects of H2 S donors (NaHS and GYY4137) on the contractility of both tissues and on micturition. The distribution of these enzymes was investigated by real-time PCR, Western blot, and immunohistochemistry. Tissue H2 S content was measured by the methylene blue method. The effects of NaHS (1 × 10-9 to 3 × 10-4 M) were evaluated on carbachol (10-5 M)-induced pre-contracted bladder strips, and on noradrenaline (10-5 M)-induced pre-contracted prostate strips, which were pretreated with propranolol (10-6 M). In addition, in urethane-anesthetized male Wistar rats, the effects of intravesically instilled GYY4137 (10-8 , 10-7 , and 10-6 M) on micturition were evaluated by cystometry. MPST and CAT were detected in the bladder and prostate, CBS was only detected in the prostate, while CSE and DAO were not detected in both tissues. Immunoreactivity of these enzymes was mainly detected in the urothelium and smooth muscle layer of the bladder and in the prostate glandular epithelium. H2 S was detected in both tissues. NaHS dose-dependently induced relaxation of pre-contracted bladder and prostate strips. Intravesically instilled GYY4137 significantly prolonged intercontraction intervals. It is possible that H2 S can function as an endogenous relaxation factor in the rat bladder and prostate.

MP09-03 HYDROGEN SULFIDE CAN FUNCTION AS AN ENDOGENOUS RELAXATION FACTOR IN THE RAT BLADDER AND PROSTATE

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology I1 Apr 2018MP09-03 HYDROGEN SULFIDE CAN FUNCTION AS AN ENDOGENOUS RELAXATION FACTOR IN THE RAT BLADDER AND PROSTATE Takahiro Shimizu, Suo Zou, Shogo Shimizu, Youichirou Higashi, Hideaki Ono, Kumiko Nakamura, Takaaki Aratake, Masaki Yamamoto, Tomoya Hamada, Yoshiki Nagao, Masashi Honda, and Motoaki Saito Takahiro ShimizuTakahiro Shimizu More articles by this author , Suo ZouSuo Zou More articles by this author , Shogo ShimizuShogo Shimizu More articles by this author , Youichirou HigashiYouichirou Higashi More articles by this author , Hideaki OnoHideaki Ono More articles by this author , Kumiko NakamuraKumiko Nakamura More articles by this author , Takaaki AratakeTakaaki Aratake More articles by this author , Masaki YamamotoMasaki Yamamoto More articles by this author , Tomoya HamadaTomoya Hamada More articles by this author , Yoshiki NagaoYoshiki Nagao More articles by this author , Masashi HondaMasashi Honda More articles by this author , and Motoaki SaitoMotoaki Saito More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.329AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES We previously reported that hydrogen sulfide (H2S), an endogenous gasotransmitter, induced relaxation on rat bladder and prostate strips (AUA2015, MP21-01). In this study, we examined (1) endogenous H2S contents and expression levels of 5 enzymes of H2S synthesis, cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), 3-mercaptopyruvate sulftransferase (MPST), cysteine aminotransferase (CAT) and D-amino acid oxidase (DAO) in the rat bladder and prostate, and (2) effects of intravesical instillation of GYY4137 (GYY), an H2S donor, on micturition in rats. METHODS (1) Bladder dome and trigone (BL-D and BL-T), and dorsolateral and ventral prostate (PR-D and PR-V) were prepared from male Wistar rats (300-400 g). H2S contents were measured by methylene blue method. Expression levels of 5 enzymes were examined by quantitative real-time PCR, western blotting and immunohistochemistry. (2) In urethane (0.8 g/kg, ip)-anesthetized male Wistar rats (300-400 g), a catheter was inserted into the bladder in order to instill reagents (2.4 ml/h) and to measure intravesical pressure. After detecting 4-5 micturition reflexes induced by saline instillation, GYY solution (10-8, 10-7 and 10-6 M, in turn) or vehicle was instilled. RESULTS (1) H2S was detected in both bladder and prostate and the content was the highest in the BL-T. In both gene and protein levels, MPST and CAT were detected in the bladder and prostate and CBS was only detected in PR-D and PR-V, while CSE and DAO were not detected in these 4 tissues. In the PR-D and PR-V, immunoreactivities of CBS, MPST and CAT were detected in the glandular epithelium (Fig. 1). In the BL-D and BL-T, MPST and CAT were detected in the urothelium and smooth muscle layers, while CBS was not detected (Fig. 1). (2) Intravesical instillation of GYY significantly prolonged intercontraction intervals compared to the vehicle-treated group (Fig. 2) without altering maximal voiding pressure. CONCLUSIONS H2S can function as an endogenous relaxation factor in the rat bladder and prostate. Therefore, endogenous H2S might open new avenues of therapeutic interventions for lower urinary tract dysfunction such as overactive bladder and benign prostatic hyperplasia. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e106 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Takahiro Shimizu More articles by this author Suo Zou More articles by this author Shogo Shimizu More articles by this author Youichirou Higashi More articles by this author Hideaki Ono More articles by this author Kumiko Nakamura More articles by this author Takaaki Aratake More articles by this author Masaki Yamamoto More articles by this author Tomoya Hamada More articles by this author Yoshiki Nagao More articles by this author Masashi Honda More articles by this author Motoaki Saito More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Role of cGMP and EDHF Pathways in Hydrogen Sulfide‐induced Vasorelaxation in the Human Artery

BackgroundEndogenous H2S generated by mercaptopyruvate sulfurtransferase (MPST) coupled with cysteine aminotransferase (CAT) in endothelium as a physical vasodilator and blood pressure regulator may play an important protective role in the pathogenesis of coronary heart disease. The present study aimed to investigate the role of cGMP and endothelium‐derived hyperpolarizing factor (EDHF) in H2S‐induced vasorelaxation in the human internal mammary artery (IMA).MethodsIn the human IMA segments from 54 patients undergoing coronary artery bypass grafting, the acetylcholine (ACh)‐induced relaxation and the effect of CAT inhibitor (aminooxyacetic acid [AOAA] and L‐aspartate) and KCa channel blocker or KATP channel blocker were studied in a myograph. Enzyme‐linked Immunosorbent Assay for PDE5A and western blotting analysis for eNOS and p‐eNOSser1177 were performed. Methylene blue assay was used to quantify the contents of H2S.ResultsThe maximal relaxation induced by ACh was significantly attenuated by AOAA or L‐aspartate, Iberiotixin (BKCa channel blocker) (P<0.01), or IKCa channel blocker plus SKCa channel blocker (TRAM‐34+Apamin) (P<0.01), or KATP channel blocker (Glibenclamide) (P<0.01). The H2S donor NaHS increased eNOS phosphorylation at its activating site S1177 and down‐regulated PDE5A activity. Incubation with ACh for 4 hours significantly increased the H2S concentration.ConclusionsWe for the first time demonstrated in the human IMA that endogenous H2S could be produced under the stimulation of ACh and that CAT is one of the key enzymes in production of H2S in the endothelial cell of the IMA. H2S may activate eNOS to produce NO that activates PKG and may also inhibit PDE5A activity; both enhance the cGMP pathway‐mediated relaxation. Further, H2S as a potential EDHF directly stimulates KCa channels to induce vasodilatation. These findings may provide new therapeutical targets for the treatment of vasospasm of coronary artery bypass grafting vessels and provide a pharmacological basis for the development of new vasodilator drugs.Support or Funding InformationSupported by grants from the National Natural Science Foundation of China (81170148 & 81641017), Zhejiang Provincial Natural Science Foundation (LY15H020008), & Tianjin Binhai Key Platform for Creative Research Program (2012‐BK110004), Binhai New Area Health Bureau (2012BWKZ008, 2016BWKY007, 2016BWKZ003).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Antioxidant and Cell-Signaling Functions of Hydrogen Sulfide in the Central Nervous System.

Hydrogen sulfide (H2S), a toxic gaseous molecule, plays a physiological role in regulating homeostasis and cell signaling. H2S is produced from cysteine by enzymes, such as cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), cysteine aminotransferase (CAT), and 3-mercaptopyruvate sulfurtransferase (3MST). These enzymes regulate the overall production of H2S in the body. H2S has a cell-signaling function in the CNS and plays important roles in combating oxidative species such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the body. H2S is crucial for maintaining balanced amounts of antioxidants to protect the body from oxidative stress, and appropriate amounts of H2S are required to protect the CNS in particular. The body regulates CBS, 3MST, and CSE levels in the CNS, and higher or lower levels of these enzymes cause various neurodegenerative diseases. This review discusses how H2S protects the CNS by acting as an antioxidant that reduces excessive amounts of ROS and RNS. Additionally, H2S regulates cell signaling to combat neuroinflammation and protect against central neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS).