Search Results (117)

Alpha-lipoic acid (ALA) is a naturally occurring organosulfur compound with antioxidant and anti-inflammatory activities. The time-dependent effects of ALA and mechanism of interaction with cystathionine-γ-lyase (CSE—an enzyme responsible for hydrogen sulfide—H₂S synthesis) in RAW 264.7 macrophages remain unknown. In this study, we report results supporting the hypothesis that anti-inflammatory effects of ALA are associated with the reduction in CSE expression. To investigate the temporal effect of ALA in lipopolysaccharide (LPS—a potent stimulator of inflammation) treated RAW 264.7 macrophages, ALA was administered 1 h before LPS stimulation and 1, 3, and 6 h post LPS stimulation. Effects of ALA on different inflammatory and oxidative stress biomarkers including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), catalase activity (CAT), and malondialdehyde (MDA) levels were investigated. LPS stimulation significantly increased TNF- α, IL-6, MCP-1, MDA levels, and CSE expression and decreased CAT activity compared with the control group (p < 0.05 to 0.0001). ALA treatment at 1000 µM significantly attenuated LPS-stimulated inflammatory response in the macrophages across different time points (p < 0.05 to 0.0001). Furthermore, we found that ALA treatment reduced the expression of CSE in both pre- and post-treated LPS-stimulated macrophages in a time-dependent manner. In conclusion, this study demonstrated for the first time that the protective effects of ALA are dependent on the reduction in CSE expression in LPS-stimulated RAW 264.7 macrophages. Full article

Cerebral ischemia–reperfusion injury triggers mitochondrial dysfunction and oxidative stress, exacerbating neuronal apoptosis. Emerging evidence highlights hydrogen sulfide (H₂S) as a gasotransmitter modulating redox balance, autophagy, and apoptosis. This study investigates the neuroprotective mechanisms of Enriched Environment (EE) against ischemic injury, focusing on mitochondrial dynamics and H₂S-mediated pathways. Using MCAO mice and OGD/R-treated SH-SY5Y neurons, interventions targeting H₂S synthesis, hypoxia-inducible factor 1-alpha (HIF-1α), and mitophagy were implemented. Behavioral, histological, and molecular analyses demonstrated EE significantly improved neurological outcomes, suppressed apoptosis, and attenuated oxidative damage (reduced MDA, elevated MnSOD/glutathione). Mechanistically, EE enhanced mitophagy via dual pathways: canonical PINK1/parkin-mediated mitochondrial clearance, corroborated by transmission electron microscope and LC3B/parkin colocalization, and non-canonical HIF-1α/BNIP3L axis activation. Transcriptomic and Co-immunoprecipitation (Co-IP) data revealed EE upregulated endogenous H₂S biosynthesis post-injury by promoting dopamine-induced calcium influx, which activated calmodulin-dependent signaling to stimulate cystathionine β-synthase/γ-lyase expression. Pharmacological blockade of H₂S synthesis or HIF-1α abolished mitochondrial protection, confirming H₂S as a central mediator. Notably, H₂S exerted antiapoptotic effects by restoring mitochondrial integrity through synergistic mitophagy activation and oxidative stress mitigation. These findings propose a novel neuroprotective cascade: EE-induced dopaminergic signaling potentiates H₂S production, which coordinates PINK1/parkin and HIF-1α/BNIP3L pathways to eliminate dysfunctional mitochondria, thereby preserving neuronal homeostasis. This study elucidates therapeutic potential of EE via H₂S-driven mitochondrial quality control, offering insights for ischemic brain injury intervention. Full article

Recent scientific reports have highlighted the physiological role, toxicological effects, and pathophysiological aspects of gasotransmitters, particularly hydrogen sulfide (H₂S), which is recognized as a new member of this family. Endogenous generation of H₂S in the skin occurs through both enzymatic and non-enzymatic pathways. The main enzymes involved in its endogenous production are cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (3-MST) and cysteine aminotransferase. 3-MST and CSE are crucial for maintaining the epidermal barrier. H₂S may play a role in oncogenesis, acting as a gas signaling molecule that disrupts mitochondrial respiration and influences immune modulation, cell proliferation, apoptosis, tumor cell survival, and metastasis. Interestingly, H₂S exhibits dual effects in the biology of skin cancer, promoting tumor growth in some contexts and exerting antitumor activities in others. Data from the European Cancer Information System and Global Cancer Observatory show a significant global increase in skin cancer cases. The most common types of cutaneous malignancies, from both epidemiological and clinical perspectives, are basal cell carcinoma. squamous cell carcinoma, and melanoma. This review aims to evaluate the dysfunctional metabolism of H₂S and the specific profiles of the enzymes that synthesize H₂S in skin cancer. By comparing the roles of H₂S in normal cells with those in cancer cells, we can enhance current understanding of its implications in skin cancer biology. This research paves the way for new clinical strategies, including the development of H₂S-modulatory therapies tailored to the dynamics of tumor progression, which could help overcome therapeutic resistance. Full article

Gliomas are central nervous system primary tumors that are distinguished by heterogeneity, broad-based infiltration, and metabolic reprogramming that sustains proliferation, invasion, and therapy refractoriness. Oxidative stress—a state of imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense—and disturbed iron metabolism are central drivers of glioma biology. The aim of this study was to evaluate ROS production, sulfane sulfur levels, the expression of proteins with antioxidant properties, such as L-cysteine-metabolizing enzymes (cystathionine β-synthase, CBS; cysteine dioxygenase 1, CDO1; cystathionine γ-lyase, CTH; 3-mercaptopyruvate sulfurtransferase, MPST; thiosulfate sulfurtransferase, TST) and non-enzymatic proteins (p53; transferrin receptor 1, TfR1), in human brain cancer cells differing in malignancy: 1321N1 astrocytoma and T98G glioblastoma. Western blotting analysis demonstrated that the expression of CBS, CDO1, and TfR1 was significantly increased in T98G cells, while CTH, MPST, TST, and p53 were comparably expressed in both cell lines. Quantitative assays revealed that T98G cells harbored significantly higher sulfane sulfur levels and higher numbers of ROS-positive cells compared to 1321N1 cells. Our results suggest that glioblastoma but not astrocytoma cells adapt sulfur and iron metabolism to provide proliferation capacity against chronic oxidative stress. It seems that CBS as well as CDO1 may significantly increase the antioxidant potential of T98G cells. In summary, this study suggests a differing metabolic vulnerability identifiable only in high-grade glioma cells and provides a potential novel molecular target for therapy. Full article

In left ventricular hypertrophy (LVH), the combined external administration of hydrogen sulfide (H₂S) and nitric oxide (NO) has been shown to reverse LVH by activating the endothelial nitric oxide synthase pathway (eNOS/NO), independent of the cystathionine γ-lyase (CSE/H₂S) pathway. Individually, both H₂S and NO have also been reported to significantly improve RCBP, restore renal excretory performance, and enhance α-adrenergic receptor responsiveness in rats. The induction of LVH was performed over a period of two weeks using drinking water with caffeine and isoprenaline. Five weeks later, the rats were fed with L-arginine (1.25 g/L) as a nitrogen oxide donor. Vascular reactions to methoxamine, phenylephrine, and noradrenaline were assessed in presences and absence of 5-methylurapidil (5-MeU), BMY7378, and chloroethylclonidine (CeC) and α1-adrenoceptor antagonists. In both the Control WKY and LVH-WKY groups, combined H₂S+NO therapy significantly (p < 0.05) upregulated the renal mRNA of CSE and eNOS when compared with untreated LVH rats. The treatment also markedly increased RCBP in LVH-H₂S+NO rats relative to LVH controls. Furthermore, H₂S+NO administration enhanced the activity of α_1A, α_1B, and α_1D adrenergic receptors in mediating renal vasoconstriction. Even under receptor blockade with high doses (HDs) of 5-MeU, CeC, and BMY 7378, renal vasoconstriction responses to adrenergic agonists like NA, PE, and ME in the LVH-H₂S+NO group remained comparable to those observed in the counterpart Control-H₂S+NO group. The findings of current study suggest that simultaneous exogenous administration of H₂S and NO donors improve renal cortical blood flow, support renal function, and augment α_1A, α_1B, and α_1D adrenergic receptor responsiveness to adrenergic agonists like NA, PE, and ME in LVH rats. This effect appears to rely primarily on the eNOS/NO pathway, with partial contribution from the CSE/H₂S pathway. Full article

Hydrogen sulfide (H₂S), nitric oxide (NO), and carbon monoxide (CO) are now recognized as key gasotranmitters that regulate vascular function, contributing to vasodilation, angiogenesis, inflammation control, and oxidative balance. Initially regarded as toxic gases, they are produced on demand by specific enzymes, including cystathionine γ-lyase (CSE), endothelial nitric oxide synthase (eNOS), and heme oxygenase-1 (HO-1). Their activity is tightly controlled by redox-sensitive pathways. Reactive oxygen species (ROS), particularly superoxide and hydrogen peroxide, modulate gasotransmitter biosynthesis at the transcriptional and post-translational levels. Moreover, ROS affect gasotransmitter availability through oxidative modifications, including thiol persulfidation, nitrosative signaling, and carbonylation. This redox regulation ensures a tightly coordinated response to environmental and metabolic cues within the vascular system. This review synthesizes the current understanding of redox–gasotransmitter interactions, highlighting how ROS modulate the vascular roles of H₂S, NO, and CO. Understanding these interactions provides critical insights into the pathogenesis of cardiovascular diseases and offers potential redox-targeted therapies. Full article

Cystathionine γ-lyase (CSE) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that catalyzes the final step of the transsulfuration pathway, converting cystathionine into cysteine. Additionally, CSE is also essential for the formation of cysteine hydropolysulfide (Cys-S-(S)n-H), known as supersulfides, by metabolizing cystine under pathological conditions. We previously reported that, during cystine metabolism, CSE undergoes self-inactivation through polysulfidation at the Cys136 residue. Here, contrary to the anticipated role of L-S-nitrosocysteine (L-CysNO) as a nitric oxide (NO) donor, we demonstrate that it serves as a substrate for CSE and that its metabolites inhibit the activity of the enzyme during L-CysNO metabolism. The in vitro incubation of CSE—but not the Cys136/171Val mutant—with L-CysNO resulted in the dose-dependent inhibition of supersulfide production, which was not reversed by the reducing agents. Notably, CSE activity remained unchanged upon preincubation with other NO donors, such as S-nitrosoglutathione or D-CysNO, but was inhibited when coincubated with cysteine. Furthermore, when PLP was removed from the CSE/L-CysNO premix, L-CysNO no longer inhibited CSE activity, suggesting that CSE metabolizes L-CysNO and that its metabolites contribute to enzyme inactivation. Indeed, we identified thionitrous acid and pyruvate as the primary CSE/L-CysNO reaction products. Thus, we establish L-CysNO as a CSE substrate and demonstrate that its metabolites act as enzyme inhibitors through a novel irreversible modification at the Cys136/171 residues. Full article

Pre-eclampsia (PE) is a hypertensive pregnancy complication. Oxidative stress is hypothesized to contribute to the pathophysiology of PE. Both the hydrogen sulfide (H₂S) and oxytocin (OT) systems might play a role in the pathophysiology of PE, like their antioxidant and hypotensive effects. Thus, the role of the interaction of the OT and H₂S systems in the context of PE was further elucidated in the present clinical case–control study “NU-HOPE” (Nürnberg-Ulm: The role of H₂S and Oxytocin Receptor in Pre-Eclampsia; ethical approval by the Landesärztekammer Bayern, file number 19033, 29 August 2019), comparing uncomplicated pregnancies, early onset PE (ePE, onset < 34 weeks gestational age) and late onset PE (lPE, onset > 34 weeks gestational age). Routine clinical data, serum H₂S and homocysteine levels, and tissue protein expression, as well as nitrotyrosine formation, were determined. The main findings were (i) unchanged plasma sulfide levels, (ii) significantly elevated homocysteine levels in ePE, but not lPE, (iii) significantly elevated expression of H₂S enzymes and OT receptor in the placenta in lPE, and (iv) significantly elevated nitrotyrosine formation in the lPE myometrium. Taken together, these findings suggest a role for the interaction of the endogenous H₂S- and OT/OTR systems in the pathophysiology of pre-eclampsia, possibly linked to impaired antioxidant protection. Full article

This study aims to investigate the mechanism by which the total flavones of Rhododendron (TFR) protect against cerebral ischemic injury through the endothelial-derived H₂S-mediated regulation of RhoA phosphorylation at the Ser188 and Rho kinase 2 (ROCK₂) phosphorylation at Thr436. For experimental design, mouse or rat cerebrovascular endothelial cells (ECs) were cultured with or without neurons and subjected to hypoxia/reoxygenation (H/R) injury. The vasodilation of the cerebral basilar artery was assessed. Cerebral ischemia/reperfusion (I/R) injury was induced in mice by bilateral carotid artery ligation, followed by Morris water maze and open field behavioral assessments. The protein levels of cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST), RhoA, ROCK₂, p-RhoA (RhoA phosphorylated at Ser188), and p-ROCK₂ (ROCK₂ phosphorylated at Thr436) were quantified. Additionally, the activities of RhoA and ROCK₂ were measured. Notably, TFR significantly inhibited H/R-induced H₂S reduction and suppressed the increased expression and activity of RhoA and ROCK₂ in ECs, effects attenuated by CSE or 3-MST knockout. Moreover, TFR-mediated cerebrovascular dilation was reduced by RhoA or ROCK₂ inhibitors, while the protective effect of TFR against cerebral I/R injury in mice was markedly attenuated by the heterozygous knockout of ROCK₂. In the ECs-co-cultured neurons, the inhibition of TFR on H/R-induced neuronal injury and decrease in H₂S level in the co-culture was attenuated by the knockout of CSE or 3-MST in the ECs. TFR notably inhibited the H/R-induced upregulation of neuronal RhoA, ROCK₂, and p-ROCK₂ protein levels, as well as the activities of RhoA and ROCK₂, while reversing the decrease in p-RhoA. However, the knockout of CSE or 3-MST in the ECs significantly attenuated the inhibition of TFR on these increases. Furthermore, 3-MST knockout in ECs attenuated the TFR-mediated suppression of p-RhoA reduction. Additionally, CSE or 3-MST knockout in ECs exacerbated H/R-induced neuronal injury, reduced H₂S level in the co-culture system, and increased RhoA activity and ROCK₂ expression in neurons. In summary, TFR protected against ischemic cerebral injury by endothelial-derived H₂S promoting the phosphorylation of RhoA at Ser188 but inhibited the phosphorylation of ROCK₂ at Thr436 to inhibit the RhoA-ROCK₂ pathway in neurons. Full article

Here, we describe the effects of double knockout (KO) of the cbs and cse genes, which are responsible for H₂S synthesis through the transsulfuration pathway, and KO of the sulfurtransferase gene (dtst1) in Drosophila melanogaster females. The analysis of H₂S production in flies showed minimal levels in the double- and triple-knockout strains. The double- (cbs-/-; cse-/-) and triple- (cbs-/-; cse-/-; dtst-/-) KO flies exhibited a shortened lifespan and reduced fecundity, and showed dramatic changes in Malpighian tubule morphology. The transcriptomic analysis revealed a profound increase in the expression levels of several genes involved in excretory system function in the double-KO and especially the triple-KO flies. Importantly, major groups of differentially expressed genes (DEGs) in the whole bodies of females and ovaries of KO strains included genes responsible for detoxification, reproduction, mitochondrial activity, excretion, cell migration, and muscle system function. The reduced fecundity observed in the double- and triple-KO flies correlated with pronounced changes in the ovarian transcriptome. At the same time, the single knockout of dtst1 increased the flies’ fecundity and lifespan. Our experiments exploring unique Drosophila strains with KO of major H₂S-related genes revealed several new pathways controlled by this ancient adaptogenic system that is involved in various human diseases and aging. Full article

Iron overload contributes to proliferative vascular diseases, yet its interplay with hydrogen sulfide (H₂S) in vascular smooth muscle cell (VSMC) proliferation remains poorly understood. This study elucidates H₂S’s role in mitigating iron-overload-induced oxidative stress and cellular damage. Using aortic VSMCs from wildtype (WT) and cystathionine γ-lyase-knockout (CSE-KO) mice treated with ferric ammonium citrate (FAC) at concentrations equivalent to serum levels of iron and citrate, we demonstrate that FAC triggers the integrated stress response (ISR) in WT cells, upregulating CSE to enhance H₂S production. The ISR mediator ATF4 activates caspases but simultaneously induces CSE, which inhibits caspase activity and promotes autophagy via AMPK signaling. In CSE-KO cells, iron overload leads to diminished Ferritin upregulation, unchecked Caspase activation, and impaired autophagy compared to WT cells. Exogenous H₂S restored iron homeostasis by enhancing Ferritin expression, activating NRF2 antioxidant pathways, and restoring apoptosis–autophagy equilibrium in both WT and KO cells. These findings establish H₂S as a critical regulator of iron-induced VSMC dysfunction, highlighting its therapeutic potential in managing vascular pathologies linked to iron dysregulation. Full article

Background/Objectives: Hydrogen sulfide (H₂S) is a vasorelaxant gas and exerts anti-oxidative, anti-inflammatory, and cytoprotective effects. H₂S has been implicated in regulating placental vaso-activity and angiogenesis. It is believed that abnormal trophoblast production of vasodilators and angiogenic factors contributes to pre-eclampsia development. However, little is known about whether aberrant H₂S production is present in placental trophoblasts from pre-eclamptic pregnancies. Methods: Trophoblasts were isolated from normal and pre-eclamptic placentas. After incubation, cell production of H₂S in the culture medium and the cellular levels of H₂S were analyzed by reversed phase high-performance liquid chromatography (RP-HPLC). Expression levels of the three key H₂S converting enzymes, cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST), were determined by immunohistochemistry. The protein expression of CBS and CSE was assessed by Western blot analysis. Results: (1) Trophoblast production and cellular levels of H₂S were significantly reduced in cells from pre-eclamptic vs. normal placentas; (2) free H₂S production was increased in a time-dependent manner in cultured trophoblasts from normal, but not from pre-eclamptic, placentas; and (3) strong CBS and CSE expression was seen in trophoblasts from normal, as opposed to pre-eclamptic, placentas. Reduced CBS and CSE expression in trophoblasts from pre-eclamptic vs. normal placentas were confirmed by Western blot analysis; and (4) 3-MST expression was undetachable in both normal and pre-eclamptic placentas, but 3-MST expression was strongly expressed in the first and second trimester placentas. Conclusions: These data provide plausible evidence that downregulation of CBS and CSE, but not 3-MST, expression may be responsible for reduced free H₂S production and decreased cellular H₂S levels in pre-eclamptic placentas. Our data provide further evidence that expression of 3-MST in placental trophoblasts is likely gestational age (developmental)-dependent. Full article

Exercise plays a crucial role in maintaining metabolic health, enhancing muscle function, and improving insulin sensitivity, thereby preventing metabolic diseases such as type 2 diabetes. Emerging evidence highlights the significance of the cystathionine γ-lyase (CSE)/hydrogen sulfide (H₂S) signaling pathway as a pivotal regulator in the molecular and physiological adaptations induced by exercise. This review comprehensively examines the biosynthesis and metabolism of H₂S, its distribution in different muscle tissues, and the mechanisms by which CSE/H₂S influences muscle contraction, repair, and protein synthesis. Additionally, it explores how CSE/H₂S modulates insulin signaling pathways, glucose uptake, and lipid metabolism, thereby enhancing insulin sensitivity. The potential of H₂S donors as exercise supplements is also discussed, highlighting their ability to improve exercise performance and metabolic health. Current research advancements, including the application of multi-omics approaches, are reviewed to provide a deeper understanding of the complex molecular networks involved. Furthermore, the challenges and future directions in CSE/H₂S research are addressed, emphasizing the need for further mechanistic studies and clinical applications. This review underscores the therapeutic potential of targeting the CSE/H₂S pathway to optimize the benefits of exercise and improve metabolic health. Full article

In recent years, a number of synthetic potentiators of antibiotics have been discovered. Their action can significantly enhance the antibacterial effect and limit the spread of antibiotic resistance through inhibition of bacterial cystathionine-γ-lyase. To expand the known set of potentiators, we developed methods for the synthesis of five new representatives of 6-bromoindole derivatives—potential inhibitors of bacterial cystathionine-γ-lyase—namely potassium 3-amino-5-((6-bromoindolyl)methyl)thiophene-2-carboxylate (MNS2) and its 6-bromoindazole analogs (MNS3 and MNS4), along with two 6-broindazole analogs of the parent compound NL2. Their syntheses are based on 6-bromoindole, 6-bromoindazole and methyl 5-(bromomethyl)-3-((ethoxycarbonyl)amino)thiophene-2-carboxylate as the main building blocks, assembling the rest of the heterocyclic system on their basis at the nitrogen atom. We assessed the ability of the new inhibitors to potentiate the antimicrobial activity of gentamicin. Full article

Both hydrogen sulfide and endocannabinoids can protect the neural retina from toxic insults under in vitro and in vivo conditions. Purpose: The aim of the present study was two-fold: (a) to examine the neuroprotective action of cannabinoids [methanandamide and 2-arachidonyl glycerol (2-AG)] against hydrogen peroxide (H₂O₂)-induced oxidative damage in the isolated bovine retina and (b) to evaluate the role of endogenously biosynthesized hydrogen sulfide (H₂S) in the inhibitory actions of cannabinoids on the oxidative stress in the bovine retina. Methods: Isolated neural retinas from cows were exposed to oxidative damage using H₂O₂ (100 µM) for 10 min. When used, tissues were pretreated with methanandamide (1 nM–100 nM) and 2-AG (1–10 µM) for 30 min before a 10 min treatment with H₂O₂ (100 µM). In some experiments, retinas were pretreated with inhibitors of the biosynthesis of H₂S [cystathionine β-synthase/cystathionine γ-lyase (CBS/CSE), aminooxyacetic acid, AOAA 30 µM, or 3-mercaptopyruvate sulfurtransferase (3MST), α-keto-butyric acid, KBA 1 mM] and the CB1-receptor antagonist, AM251 (100 nM) for 30 min before treatment with methanandamide (1 nM–100 µM). Enzyme immunoassay measurement of 8-epi PGF2α (8-isoprostane) levels was performed to assess lipid peroxidation in retinal tissues. Results: In the presence of H₂O₂ (100 µM), methanandamide (1 nM–100 µM) and 2-AG (1–10 µM) significantly (p < 0.001) blocked the H₂O₂-induced elevation in 8-isoprostane levels in the isolated bovine retina. In the presence of the CB1 antagonist AM251 (100 nM), the effect of methanandamide (1 nM) on the H₂O₂-induced 8-isoprostane production was significantly (p < 0.001) attenuated. While AOAA (30 µM) had no significant (p > 0.05) effect on the inhibition of H₂O₂-induced oxidative stress elicited by methanandamide, KBA (1 mM) reversed the neuroprotective action of methanandamide. Conclusions: The cannabinoids, methanandamide and 2-AG can prevent H₂O₂-induced oxidative stress in the isolated bovine retina. The neuroprotective actions of cannabinoids are partially dependent upon the activation of the CB1 receptors and endogenous production of H₂S via the 3-MST/CAT pathway. Full article