Abstract Hydrogen sulfide (H 2 S) is an important signaling molecule whose up‐ and down‐regulation have specific biological consequences. Although significant advances in H 2 S up‐regulation, by the development of H 2 S donors, have been achieved in recent years, precise H 2 S down‐regulation is still challenging. The lack of potent/specific inhibitors for H 2 S‐producing enzymes contributes to this problem. We expect the development of H 2 S scavengers is an alternative approach to address this problem. Since chemical sensors and scavengers of H 2 S share the same criteria, we constructed a H 2 S sensor database, which summarizes key parameters of reported sensors. Data‐driven analysis led to the selection of 30 potential compounds. Further evaluation of these compounds identified a group of promising scavengers, based on the sulfonyl azide template. The efficiency of these scavengers in in vitro and in vivo experiments was demonstrated.
Methylmercury (MeHg) is an electrophilic environmental neurotoxicant that is biologically concentrated into seafood. High-dose MeHg exposure leads covalent modification of protein thiol groups to form S-mercuration (MeHg-S-protein). This pathological protein modification, in part, explains the neurotoxicity of MeHg. Epidemiological studies have also suggested that MeHg increases cardiac risk at a lower concentration than that associated with neurotoxicity. However, the underlying mechanism is unclear. We previously identified that aberrant mitochondrial fission induced by hypoxic stress cause cardiac vulnerability. Here we show that exposure to a low dose of MeHg increased cardiac risk induced by pressure overload in mice. MeHg exposure caused mitochondrial hyperfission in myocardium through the activation of mitochondrial fission factor Drp1. MeHg treatment promoted Drp1 activation by increasing the interaction between Drp1 and its guanine nucleotide exchange factor filamin A. Modification of cysteine residues in proteins with polysulfides play an indispensable role in redox signaling and mitochondrial homeostasis in mammalian cells. Drp1 activity was negatively regulated by polysulfidation at Cys624, a redox-sensitive residue. MeHg exposure induced the depolysulfidation of Cys624 in Drp1, which led to filamin A-dependent activation of Drp1 and mitochondrial hyperfission. Other environmental pollutant, cigarette sidestream smoke that is a significant contributor to increased cardiovascular mortality also led cardiomyocyte dysfunction through Drp1 depolysulfidation. Treatment with NaHS, which acts as a donor for reactive polysulfides, reversed MeHg-evoked Drp1 depolysulfidation and vulnerability to mechanical load in rodent and human cardiomyocytes and mouse hearts. These results suggest that depolysulfidation of Drp1 at Cys624 by environmental stress such as MeHg increases cardiac fragility to mechanical load through filamin-dependent mitochondrial hyperfission.
Cysteine-bound sulfane sulfur atoms in proteins have received much attention as key factors in cellular redox homeostasis. However, the role of sulfane sulfur in zinc regulation has been overlooked. We report here that cysteine-bound sulfane sulfur atoms serve as ligands to hold and release zinc ions in growth inhibitory factor (GIF)/metallothionein-3 (MT3) with an unexpected C–S–S–Zn structure. Oxidation of such a zinc/persulfide cluster in Zn 7 GIF/MT3 results in the release of zinc ions, and intramolecular tetrasulfide bridges in apo-GIF/MT3 efficiently undergo S–S bond cleavage by thioredoxin to regenerate Zn 7 GIF/MT3. Three-dimensional molecular modeling confirmed the critical role of the persulfide group in the thermostability and Zn-binding affinity of GIF/MT3. The present discovery raises the fascinating possibility that the function of other Zn-binding proteins is controlled by sulfane sulfur.
The physiological functions of supersulfides, inorganic and organic sulfides with sulfur catenation, have been extensively studied. Their synthesis is mainly mediated by mitochondrial cysteinyl-tRNA synthetase (CARS2) that functions as a principal cysteine persulfide synthase. This study aimed to investigate the role of supersulfides in joint homeostasis and bone regeneration. Using Cars2AINK/+ mutant mice, in which the KIIK motif of CARS2 essential for supersulfide production was replaced with AINK, we evaluated the role of supersulfides in fracture healing and cartilage homeostasis during osteoarthritis (OA). Tibial fracture surgery was performed on the wild-type (Cars2+/+) and Cars2AINK/+ mice littermates. Bulk RNA-seq analysis for the osteochondral regeneration in the fracture model showed increased inflammatory markers and reduced osteogenic factors, indicative of impaired bone regeneration, in Cars2AINK/+ mice. Destabilization of the medial meniscus (DMM) surgery was performed to produce the mouse OA model. Histological analyses with Osteoarthritis Research Society International and synovitis scores revealed accelerated OA progression in Cars2AINK/+ mice compared with that in Cars2+/+ mice. To assess the effects of supersulfides on OA progression, glutathione trisulfide (GSSSG) or saline was periodically injected into the mouse knee joints after the DMM surgery. Thus, supersulfides derived from CARS2 and GSSSG exogenously administered significantly inhibited inflammation and lipid peroxidation of the joint cartilage, possibly through suppression of ferroptosis, during OA development. This study represents a significant advancement in understanding anti-inflammatory and anti-oxidant functions of supersulfides in skeletal tissues and may have a clinical relevance for the bone healing and OA therapeutics.
Cysteine-bound sulfane sulfur atoms in proteins have received much attention as key factors in cellular redox homeostasis. However, the role of sulfane sulfur in zinc regulation has been underinvestigated. We report here that cysteine-bound sulfane sulfur atoms serve as ligands to hold and release zinc ions in growth inhibitory factor (GIF)/metallothionein-3 (MT-3) with an unexpected C– S–S–Zn structure. Oxidation of such a zinc/persulfide cluster in Zn 7 GIF/MT-3 results in the release of zinc ions, and intramolecular tetrasulfide bridges in apo-GIF/MT-3 efficiently undergo S–S bond cleavage by thioredoxin to regenerate Zn 7 GIF/MT-3. Three-dimensional molecular modeling confirmed the critical role of the persulfide group in the thermostability and Zn-binding affinity of GIF/MT-3. The present discovery raises the fascinating possibility that the function of other Zn-binding proteins is controlled by sulfane sulfur.
Cysteine-bound sulfane sulfur atoms in proteins have received much attention as key factors in cellular redox homeostasis. However, the role of sulfane sulfur in zinc regulation has been overlooked. We report here that cysteine-bound sulfane sulfur atoms serve as ligands to hold and release zinc ions in growth inhibitory factor (GIF)/metallothionein-3 (MT3) with an unexpected C–S–S–Zn structure. Oxidation of such a zinc/persulfide cluster in Zn7GIF/MT3 results in the release of zinc ions, and intramolecular tetrasulfide bridges in apo-GIF/MT3 efficiently undergo S–S bond cleavage by thioredoxin to regenerate Zn7GIF/MT3. Three-dimensional molecular modeling confirmed the critical role of the persulfide group in the thermostability and Zn-binding affinity of GIF/MT3. The present discovery raises the fascinating possibility that the function of other Zn-binding proteins is controlled by sulfane sulfur.
Abstract The mammalian brain is highly vulnerable to oxygen deprivation, yet the mechanism underlying the brain’s sensitivity to hypoxia is incompletely understood. Hypoxia induces accumulation of hydrogen sulfide, a gas that inhibits mitochondrial respiration. Here, we show that, in mice, rats, and naturally hypoxia-tolerant ground squirrels, the sensitivity of the brain to hypoxia is inversely related to the levels of sulfide:quinone oxidoreductase (SQOR) and the capacity to catabolize sulfide. Silencing SQOR increased the sensitivity of the brain to hypoxia, whereas neuron-specific SQOR expression prevented hypoxia-induced sulfide accumulation, bioenergetic failure, and ischemic brain injury. Excluding SQOR from mitochondria increased sensitivity to hypoxia not only in the brain but also in heart and liver. Pharmacological scavenging of sulfide maintained mitochondrial respiration in hypoxic neurons and made mice resistant to hypoxia. These results illuminate the critical role of sulfide catabolism in energy homeostasis during hypoxia and identify a therapeutic target for ischemic brain injury.
Abstract Sulfite oxidase (SOX) deficiency is a rare inborn error of cysteine metabolism resulting in severe neurological damage. In patients, sulfite accumulates to toxic levels causing a raise in downstream products S -sulfocysteine (SSC), mediating excitotoxicity, and thiosulfate, a catabolic intermediate/product of H 2 S metabolism. Here, we report a full-body knock-out mouse model for SOX deficiency (SOXD) with a severely impaired phenotype. Amongst the urinary biomarkers, thiosulfate showed a 45-fold accumulation in SOXD mice representing the major excreted S-metabolite. Consistently, we found increased plasma H 2 S, which was derived from sulfite-induced release from persulfides as demonstrated in vitro and in vivo . Mass spectrometric analysis of total protein persulfidome identified a major loss of persulfidation in 20% of the proteome affecting enzymes in amino acids and fatty acid metabolism. Urinary amino acid profiles indicate metabolic rewiring suggesting partial reversal of the TCA cycle thus identifying a novel contribution of H 2 S metabolism and persulfidation in SOXD.
