Sulfur amino acid metabolism: pathways for production and removal of homocysteine and cysteine

H2S-Synthesizing Enzymes Are Putative Determinants in Lung Cancer Management toward Personalized Medicine

Lung cancer is a lethal disease with no truly efficient therapeutic management despite the progresses, and metabolic profiling can be a way of stratifying patients who may benefit from new therapies. The present study is dedicated to profiling cysteine metabolic pathways in NSCLC cell lines and tumor samples. This was carried out by analyzing hydrogen sulfide (H2S) and ATP levels, examining mRNA and protein expression patterns of cysteine catabolic enzymes and transporters, and conducting metabolomics analysis using nuclear magnetic resonance (NMR) spectroscopy. Selenium-chrysin (SeChry) was tested as a therapeutic alternative with the aim of having an effect on cysteine catabolism and showed promising results. NSCLC cell lines presented different cysteine metabolic patterns, with A549 and H292 presenting a higher reliance on cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) to maintain H2S levels, while the PC-9 cell line presented an adaptive behavior based on the use of mercaptopyruvate sulfurtransferase (MST) and cysteine dioxygenase (CDO1), both contributing to the role of cysteine as a pyruvate source. The analyses of human lung tumor samples corroborated this variability in profiles, meaning that the expression of certain genes may be informative in defining prognosis and new targets. Heterogeneity points out individual profiles, and the identification of new targets among metabolic players is a step forward in cancer management toward personalized medicine.

Dietary methionine sources and levels modulate the intestinal health status of broiler chickens

Given the key role of methionine in biological processes, adequate methionine should be provided to meet the nutritional requirements. DL-2-hydroxy-4-(methylthio)-butanoic acid (DL-HMTBA) has been considered as an important source of methionine. However, the effects of different sources and levels of methionine on the intestinal health status have not been clarified yet. An experiment was carried out to investigate the effects of different dietary sources and levels of methionine on the intestinal epithelial barrier, inflammatory cytokines expression, ileal morphology, microbiota composition, and cecal short chain fatty acids (SCFA) profiles. For this purpose, 720 male Arbor Acre broiler chicks at 1 d old were randomly assigned to a 2 × 3 factorial arrangement with 2 methionine sources (DL-methionine and DL-HMTBA) and 3 total sulfur amino acids (TSAA) levels (80%, 100%, and 120% of Arbor Acre recommendation). The results showed that DL-HMTBA supplementation promoted intestinal physical barrier at both gene expression level of claudin-1 and serum diamine oxidase level (P < 0.05), and the inflammatory cytokine IL-6 mRNA expression was down-regulated by dietary DL-HMTBA supplementation compared with the DL-methionine group (P < 0.05). Meanwhile, an upregulated gene expression of claudin-1 and zonula occluden-1 (ZO-1) were observed in the low-TSAA treatment on d 14 (P < 0.05), whereas this treatment increased the expression of IL-1β and IL-6 (P < 0.05). Villus height to crypt depth ratio was high (P < 0.05) in the middle-level TSAA group. Furthermore, DL-HMTBA supplementation optimized the microbiota of the ileum especially the relative abundance of Lactobacillus, where the digestion and absorption were completed, and elevated the concentrations of SCFA (acetate, propionate, and butyrate) in the cecal content on d 21 (P < 0.01). In conclusion, dietary DL-HMTBA supplementation improved the intestinal barrier function, immune homeostasis and optimized the microbiota to promote intestinal health status in broiler chickens.

The Role of Cystathionine-β-Synthase, H2S, and miRNA-377 in Hypoxic-Ischemic Encephalopathy: Insights from Human and Animal Studies

We aimed to investigate the mechanism underlying the roles of miRNA-377, Cystathionine-β-synthase (CBS), and hydrogen sulfide (H2S) in the development of hypoxic-ischemic encephalopathy (HIE). We investigated the relationship between CBS, H2S, and miR-377 in both humans with HIE and animals with hypoxic-ischemic insult. An animal model of fetal rats with hypoxic-ischemic brain injury was established, and the fetal rats were randomly assigned to control and hypoxic-ischemic groups for 15 min (mild) and 30 min (moderate) groups. Human samples were collected from children diagnosed with HIE. Healthy or non-neurological disease children were selected as the control group. Hematoxylin-eosin (HE) staining, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and western blot were used to conduct this study. Hypoxia-ischemia induced pathological alterations in brain tissue changes were more severe in groups with severe hypoxic insult. miRNA-377 expression levels were upregulated in brain tissue and serum of fetal rats and human samples with HIE compared to controls. Conversely, CBS and H2S expression levels were significantly decreased in both human and animal samples compared to controls. Our findings suggest that CBS is a target gene of miR-377 which may contribute to the development of HIE by regulating CBS/H2S. H2S has a protective effect against hypoxic damage in brain tissue. The study provides new insights into the potential mechanisms underlying the protective role of H2S in hypoxic brain damage and may contribute to the development of novel therapies for HIE.

The effects of in ovo injection with sulfur amino acids and folic acid on the gene expression, relative organ weights, hematologic parameters, performance, and carcass characteristics of broiler chickens

This study aimed to evaluate the effect of in ovo injection of folic acid (FA) and sulfur amino acids (SAAs) on the mitotic activity of myocytes, performance, relative organ weight, hematological values, and characteristics of broiler chicken carcasses. A total of 1200 fertile eggs from 42-week-old Ross AP© breeders were inoculated in the albumen on the first day of incubation in a completely randomized design with one of the treatments: C-intact eggs; SS: inoculation with 0.5 mL of saline solution; FA: 0.150 mg of FA; SAA: 5.90 mg of L-methionine and 3.40 mg of L-cysteine; or FA/SAA: FA + SAA. The inoculation of SAA did not influence (p > 0.05) the post-hatching characteristics of the chickens. FA inoculation increased (p < 0.05) the expression of the PAX7 and MYF genes in the pectoralis muscle of hatched chicks and reduced (p < 0.05) feed conversion at 42 days of age. The combination of SAA + FA increased (p < 0.05) the depth of the ileal crypt on the 1st day after hatching and the relative weight of the spleen and thymus on the 21st day of life. In conclusion, the inoculation of FA on the 1st day of incubation increases gene expression and improves the performance of broilers.

Chromatin balances cell redox and energy homeostasis

Chromatin plays a central role in the conversion of energy in cells: alteration of chromatin structure to make DNA accessible consumes energy, and compaction of chromatin preserves energy. Alteration of chromatin structure uses energy sources derived from carbon metabolism such as ATP and acetyl-CoA; conversely, chromatin compaction and epigenetic modification feedback to metabolism and energy homeostasis by controlling gene expression and storing metabolites. Coordination of these dual chromatin events must be flexibly modulated in response to environmental changes such as during development and exposure to stress. Aging also alters chromatin structure and the coordination of metabolism, chromatin dynamics, and other cell processes. Noncoding RNAs and other RNA species that associate directly with chromatin or with chromatin modifiers contribute to spatiotemporal control of transcription and energy conversion. The time required for generating the large amounts of RNAs and chromatin modifiers observed in super-enhancers may be critical for regulation of transcription and may be impacted by aging. Here, taking into account these factors, we review alterations of chromatin that are fundamental to cell responses to metabolic changes due to stress and aging to maintain redox and energy homeostasis. We discuss the relationship between spatiotemporal control of energy and chromatin function, as this emerging concept must be considered to understand how cell homeostasis is maintained.

Dissecting molecular mechanisms underlying ferroptosis in human umbilical cord mesenchymal stem cells: Role of cystathionine γ-lyase/hydrogen sulfide pathway

BACKGROUND

Ferroptosis can induce low retention and engraftment after mesenchymal stem cell (MSC) delivery, which is considered a major challenge to the effectiveness of MSC-based pulmonary arterial hypertension (PAH) therapy. Interestingly, the cystathionine γ-lyase (CSE)/hydrogen sulfide (H2S) pathway may contribute to mediating ferroptosis. However, the influence of the CSE/H2S pathway on ferroptosis in human umbilical cord MSCs (HUCMSCs) remains unclear.

AIM

To clarify whether the effect of HUCMSCs on vascular remodelling in PAH mice is affected by CSE/H2S pathway-mediated ferroptosis, and to investigate the functions of the CSE/H2S pathway in ferroptosis in HUCMSCs and the underlying mechanisms.

METHODS

Erastin and ferrostatin-1 (Fer-1) were used to induce and inhibit ferroptosis, respectively. HUCMSCs were transfected with a vector to overexpress or inhibit expression of CSE. A PAH mouse model was established using 4-wk-old male BALB/c nude mice under hypoxic conditions, and pulmonary pressure and vascular remodelling were measured. The survival of HUCMSCs after delivery was observed by in vivo bioluminescence imaging. Cell viability, iron accumulation, reactive oxygen species production, cystine uptake, and lipid peroxidation in HUCMSCs were tested. Ferroptosis-related proteins and S-sulfhydrated Kelch-like ECH-associating protein 1 (Keap1) were detected by western blot analysis.

RESULTS

In vivo, CSE overexpression improved cell survival after erastin-treated HUCMSC delivery in mice with hypoxia-induced PAH. In vitro, CSE overexpression improved H2S production and ferroptosis-related indexes, such as cell viability, iron level, reactive oxygen species production, cystine uptake, lipid peroxidation, mitochondrial membrane density, and ferroptosis-related protein expression, in erastin-treated HUCMSCs. In contrast, in vivo, CSE inhibition decreased cell survival after Fer-1-treated HUCMSC delivery and aggravated vascular remodelling in PAH mice. In vitro, CSE inhibition decreased H2S levels and restored ferroptosis in Fer-1-treated HUCMSCs. Interestingly, upregulation of the CSE/H2S pathway induced Keap1 S-sulfhydration, which contributed to the inhibition of ferroptosis.

CONCLUSION

Regulation of the CSE/H2S pathway in HUCMSCs contributes to the inhibition of ferroptosis and improves the suppressive effect on vascular remodelling in mice with hypoxia-induced PAH. Moreover, the protective effect of the CSE/H2S pathway against ferroptosis in HUCMSCs is mediated via S-sulfhydrated Keap1/nuclear factor erythroid 2-related factor 2 signalling. The present study may provide a novel therapeutic avenue for improving the protective capacity of transplanted MSCs in PAH.

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.

Activation of the integrated stress response rewires cardiac metabolism in Barth syndrome

Barth Syndrome (BTHS) is an inherited cardiomyopathy caused by defects in the mitochondrial transacylase TAFAZZIN (Taz), required for the synthesis of the phospholipid cardiolipin. BTHS is characterized by heart failure, increased propensity for arrhythmias and a blunted inotropic reserve. Defects in Ca2+-induced Krebs cycle activation contribute to these functional defects, but despite oxidation of pyridine nucleotides, no oxidative stress developed in the heart. Here, we investigated how retrograde signaling pathways orchestrate metabolic rewiring to compensate for mitochondrial defects. In mice with an inducible knockdown (KD) of TAFAZZIN, and in induced pluripotent stem cell-derived cardiac myocytes, mitochondrial uptake and oxidation of fatty acids was strongly decreased, while glucose uptake was increased. Unbiased transcriptomic analyses revealed that the activation of the eIF2α/ATF4 axis of the integrated stress response upregulates one-carbon metabolism, which diverts glycolytic intermediates towards the biosynthesis of serine and fuels the biosynthesis of glutathione. In addition, strong upregulation of the glutamate/cystine antiporter xCT increases cardiac cystine import required for glutathione synthesis. Increased glutamate uptake facilitates anaplerotic replenishment of the Krebs cycle, sustaining energy production and antioxidative pathways. These data indicate that ATF4-driven rewiring of metabolism compensates for defects in mitochondrial uptake of fatty acids to sustain energy production and antioxidation.

Hypoxia-inducible factor induces cysteine dioxygenase and promotes cysteine homeostasis in Caenorhabditis elegans

Dedicated genetic pathways regulate cysteine homeostasis. For example, high levels of cysteine activate cysteine dioxygenase, a key enzyme in cysteine catabolism in most animal and many fungal species. The mechanism by which cysteine dioxygenase is regulated is largely unknown. In an unbiased genetic screen for mutations that activate cysteine dioxygenase (cdo-1) in the nematode C. elegans, we isolated loss-of-function mutations in rhy-1 and egl-9, which encode proteins that negatively regulate the stability or activity of the oxygen-sensing hypoxia inducible transcription factor (hif-1). EGL-9 and HIF-1 are core members of the conserved eukaryotic hypoxia response. However, we demonstrate that the mechanism of HIF-1-mediated induction of cdo-1 is largely independent of EGL-9 prolyl hydroxylase activity and the von Hippel-Lindau E3 ubiquitin ligase, the classical hypoxia signaling pathway components. We demonstrate that C. elegans cdo-1 is transcriptionally activated by high levels of cysteine and hif-1. hif-1-dependent activation of cdo-1 occurs downstream of an H2S-sensing pathway that includes rhy-1, cysl-1, and egl-9. cdo-1 transcription is primarily activated in the hypodermis where it is also sufficient to drive sulfur amino acid metabolism. Thus, the regulation of cdo-1 by hif-1 reveals a negative feedback loop that maintains cysteine homeostasis. High levels of cysteine stimulate the production of an H2S signal. H2S then acts through the rhy-1/cysl-1/egl-9 signaling pathway to increase HIF-1-mediated transcription of cdo-1, promoting degradation of cysteine via CDO-1.

Lysosomal cyst(e)ine storage potentiates tolerance to oxidative stress in cancer cells

Cyst(e)ine is a key precursor for the synthesis of glutathione (GSH), which protects cancer cells from oxidative stress. Cyst(e)ine is stored in lysosomes, but its role in redox regulation is unclear. Here, we show that breast cancer cells upregulate major facilitator superfamily domain containing 12 (MFSD12) to increase lysosomal cyst(e)ine storage, which is released by cystinosin (CTNS) to maintain GSH levels and buffer oxidative stress. We find that mTORC1 regulates MFSD12 by directly phosphorylating residue T254, while mTORC1 inhibition enhances lysosome acidification that activates CTNS. This switch modulates lysosomal cyst(e)ine levels in response to oxidative stress, fine-tuning redox homeostasis to enhance cell fitness. MFSD12-T254A mutant inhibits MFSD12 function and suppresses tumor progression. Moreover, MFSD12 overexpression correlates with poor neoadjuvant chemotherapy response and prognosis in breast cancer patients. Our findings reveal the critical role of lysosomal cyst(e)ine storage in adaptive redox homeostasis and suggest that MFSD12 is a potential therapeutic target.

Recent Review on the Extraction and Qualitative Assay of Cysteine and Other Amino Acids from Vellore Feather Waste and Molecular Docking Studies of Cysteine for Pharmacological Applications

Products produced from waste are a relatively recent innovation. Feather substrates are abundant in keratin content and improper disposal can cause ecosystem contamination. However, these pollutants can be transformed into value-added products for industrial application. Physical, chemical and cutting-edge microbiological methods were utilized for decomposing keratin and aid in the identification and estimation of amino acids from poultry feather wastes. These beneficial approaches are receiving more attention due to their retrieval of harmless and value added byproducts. These keratin-based compounds are used widely in pharmaceutical, livestock feed, fertilizer, and a variety of other industrial sectors. Since keratin is primarily consisting of amino acids, it can be utilized to affirm and estimate the amino acids in these feather substrates. This study primarily highlights the various methodologies employed for the qualitative estimation of amino acids in feather waste samples and the inhibitory activity of keratinase enzyme by EDTA and pepstatin in order to accumulate amino acids for drug delivery purpose and their importance in various pharmaceutical industries. In addition to that, molecular docking studies of cysteine with many standard pharmaceutical drugs like acetaminophen, pethidine, methylphenidate, carbamazepine, cillin and amlodipine were performed using autodock to demonstrate how cysteine greatly reduces conventional drug toxicity and its side effects.

Pathological role of methionine in the initiation and progression of biliary atresia

Methionine (Met) is an essential amino acid, and its excessive dietary intake and/or its metabolism disturbance could lead to accumulation/depletion of hepatic Met and some of the key intermediates of these pathways, which would interfere normal liver function and would be associated with liver diseases. Biliary atresia (BA) is a life-threatening disease characterized by inflammatory fibrosclerosing changes of the intrahepatic and extrahepatic biliary systems and is the primary cause of obstructive neonatal cholestasis with a rapid course of liver failure. However, its pathogenesis remains unknown. Previous studies reported elevated Met level in patients with obstructive cholestasis, suggesting a potential link between Met and BA. This paper reviews the Met metabolism in normal conditions and its dysregulation under abnormal conditions, the possible causes of hypermethioninemia, and its connection to BA pathogenesis: Abnormal hepatic level of Met could lead to a perturbation of redox homeostasis and mitochondrial functions of hepatocytes, enhancement of viral infectivity, and dysregulation of innate and adaptative immune cells in response to infection/damage of the liver contributing to the initiation/progression of BA.

Dietary supplementation with 2-hydroxy-4-methyl(thio) butanoic acid and DL-methionine improves productive performance, egg quality and redox status of commercial laying ducks

This experiment aimed to study the effects of supplemental methionine sources, 2-hydroxy-4 methyl(thio) butanoic acid (HMTBa) and DL-Methionine (DL-Met), on productive performance, egg quality, and redox status of laying ducks. A total of 792 healthy 25-wk-old Longyan laying ducks with similar body weights were randomly allotted to 11 treatment groups. Each treatment group had 6 replicates of 12 ducks. The trial lasted for 16 wk. Ducks were fed a basal deficient diet (Met: 0.24%; Met + Cys: 0.51%) or supplemented with DL-Met or HMTBa at 0.05%, 0.12%, 0.19%, 0.26%, and 0.33% of diet, respectively. Compared with the basal diet, supplementation with either DL-Met or HMTBa increased the average egg weight, egg mass, and decreased feed to egg ratio during the whole trial period (P < 0.05). Albumen weight and its ratio to total egg weight were increased, but yolk and shell ratio, albumen height, Haugh unit and shell breaking strength were decreased (P < 0.05). Dietary DL-Met or HMTBa supplementation increased taurine, methionine, leucine, tryptophan and arginine content, and decreased serine and lysine content in plasma (P < 0.05). The redox status of laying ducks was improved by enhancing the glutathione peroxidase and catalase activities, glutathione content and its ratio relative to glutathione (oxidized) content and decreasing malondialdehyde content and increasing mRNA expression of superoxide dismutase-1, glutathione peroxidase-1, hemeoxygenase-1 and nuclear factor-like 2 in liver and ileum with the supplementation of DL-Met or HMTBa (P < 0.05). Liver health status measured by average area proportion lipid droplet was improved with supplementation of DL-Met or HMTBa (P < 0.05). Villus height and villus height to crypt depth ratio in the ileum and the ileal gene expression of tight junction protein and occludin were increased with DL-Met or HMTBa supplementation (P < 0.05). Taken together, these results suggested that the efficacy of dietary supplementation of HMTBa was similar to DL-Met, and it ranged from 98% to 100% for productive performance and egg albumen ratio in laying ducks (25 to 41 wk).

Sulfur-Element containing metabolic pathways in human health and crosstalk with the microbiome

In humans, methionine derived from dietary proteins is necessary for cellular homeostasis and regeneration of sulfur containing pathways, which produce inorganic sulfur species (ISS) along with essential organic sulfur compounds (OSC). In recent years, inorganic sulfur species have gained attention as key players in the crosstalk of human health and the gut microbiome. Endogenously, ISS includes hydrogen sulfide (H2S), sulfite (SO32-), thiosulfate (S2O32-), and sulfate (SO42-), which are produced by enzymes in the transsulfuration and sulfur oxidation pathways. Additionally, sulfate-reducing bacteria (SRB) in the gut lumen are notable H2S producers which can contribute to the ISS pools of the human host. In this review, we will focus on the systemic effects of sulfur in biological pathways, describe the contrasting mechanisms of sulfurylation versus phosphorylation on the hydroxyl of serine/threonine and tyrosine residues of proteins in post-translational modifications, and the role of the gut microbiome in human sulfur metabolism.

Advances in the understanding of acetaminophen toxicity mechanisms: a clinical toxicology perspective

INTRODUCTION

Acetaminophen (paracetamol) is a commonly used analgesic and antipyretic agent, which is safe in therapeutic doses. Acetaminophen poisoning due to self-harm or repeated supratherapeutic ingestion is a common cause of acute liver injury. Acetylcysteine has been a mainstay of treatment for acetaminophen poisoning for decades and is efficacious if administered early. However, treatment failures occur if administered late, in 'massive' overdoses or in high-risk patients.

AREAS COVERED

This review provides an overview of the mechanisms of toxicity of acetaminophen poisoning (metabolic and oxidative phase) and how this relates to the assessment and treatment of the acetaminophen poisoned patient. The review focuses on how these advances offer further insight into the utility of novel biomarkers and the role of proposed adjunct treatments.

EXPERT OPINION

Advances in our understanding of acetaminophen toxicity have allowed the development of novel biomarkers and a better understanding of how adjunct treatments may prevent acetaminophen toxicity. Newly proposed adjunct treatments like fomepizole are being increasingly used without robust clinical trials. Novel biomarkers (not yet clinically available) may provide better assessment of these newly proposed adjunct treatments, particularly in clinical trials. These advances in our understanding of acetaminophen toxicity and liver injury hold promise for improved diagnosis and treatment.

Glutathione limits RUNX2 oxidation and degradation to regulate bone formation

Reactive oxygen species (ROS) are natural products of mitochondrial oxidative metabolism and oxidative protein folding. ROS levels must be well controlled, since elevated ROS has been shown to have deleterious effects on osteoblasts. Moreover, excessive ROS is thought to underlie many of the skeletal phenotypes associated with aging and sex steroid deficiency in mice and humans. The mechanisms by which osteoblasts regulate ROS and how ROS inhibits osteoblasts are not well understood. Here, we demonstrate that de novo glutathione (GSH) biosynthesis is essential in neutralizing ROS and establish a proosteogenic reduction and oxidation reaction (REDOX) environment. Using a multifaceted approach, we demonstrate that reducing GSH biosynthesis led to acute degradation of RUNX2, impaired osteoblast differentiation, and reduced bone formation. Conversely, reducing ROS using catalase enhanced RUNX2 stability and promoted osteoblast differentiation and bone formation when GSH biosynthesis was limited. Highlighting the therapeutic implications of these findings, in utero antioxidant therapy stabilized RUNX2 and improved bone development in the Runx2+/- haplo-insufficient mouse model of human cleidocranial dysplasia. Thus, our data establish RUNX2 as a molecular sensor of the osteoblast REDOX environment and mechanistically clarify how ROS negatively impacts osteoblast differentiation and bone formation.

BODIPY-based fluorescent probe for cysteine detection and its applications in food analysis, test strips and biological imaging

Cysteine, as one of semi-essential amino acids, which is absorbed from protein-rich foods and acts considerable role in various physiological processes. Here, we designed and synthesized a BODIPY-based turn-on fluorescent probe BDP-S for detecting Cys. The probe displayed short reaction time (10 min), distinct color response (from blue to pink), large signal noise ratio (3150-fold), high selectivity and sensitivity (LOD = 11.2 nM) toward Cys. Moreover, BDP-S could not only be used for quantitative determination of Cys in food samples, but also be conveniently deposited on the test strips for qualitative detection of Cys. Notably, BDP-S was successfully used for imaging Cys in living cells and in vivo. Consequently, this work provided a hopefully powerful tool for detecting Cys in food samples and complex biological systems.

Hydrogen sulfide and epigenetics: Novel insights into the cardiovascular effects of this gasotransmitter

Epigenetics studies the heritable modifications of genome expression that do not affect the nucleotide sequence. Epigenetic modifications can be divided into: DNA methylation, histone modifications, and modulation of genome expression by non-coding RNAs. Alteration of these mechanisms can alter the phenotype, and can lead to disease onset. The endogenous gasotransmitter hydrogen sulfide (H2 S) plays pleiotropic roles in many systems, including the cardiovascular (CV) system, and its mechanism of action mainly includes S-persulfidation of cysteine residues. Recent evidence suggests that many H2 S-mediated biological activities are based on the epigenetic regulation of cellular function, with effects ranging from DNA methylation to modification of histones and regulation of non-coding RNAs. This review describes the role of H2 S-regulating epigenetic mechanisms, providing a panorama of the current literature, and offers a novel scenario for the development of H2 S-releasing 'epidrugs' with a potential clinical use in the prevention and treatment of many CV and non-CV disorders.

Serum 5-Methyltetrahydrofolate Status Is Associated with One-Carbon Metabolism-Related Metabolite Concentrations and Enzyme Activity Indicators in Young Women

Maintaining optimal one-carbon metabolism (OCM) is essential for health and pregnancy. In this cross-sectional study, folate status was assessed based on 5-methyltetrahydrofolate (5-MTHF) levels, and the association between 5-MTHF and OCM-related metabolites was investigated in 227 female Japanese university students aged 18-25 years. The participants were divided into high and low 5-MTHF groups based on their folate status. Serum samples of the participants were collected while they were fasting, and 18 OCM-related metabolites were measured using stable-isotope dilution liquid chromatography-electrospray tandem mass spectrometry. The association between serum 5-MTHF and OCM-related metabolite concentrations was assessed using Spearman's rank correlation coefficient. Serum 5-MTHF concentrations were negatively correlated with total homocysteine (tHcy) concentrations and positively correlated with S-adenosylmethionine (SAM) and total cysteine (tCys) concentrations. Serum 5-MTHF concentrations demonstrated a stronger negative correlation with tHcy/tCys than with tHcy alone. The negative correlation between betaine and tHcy concentrations was stronger in the low 5-MTHF group than in the high 5-MTHF group. The 5-MTHF status could be linked to Hcy flux into the transsulfuration pathway via SAM. Therefore, the tHcy/tCys ratio may be a more sensitive indicator of the 5-MTHF status than tHcy alone. Furthermore, a low 5-MTHF status can enhance Hcy metabolism via betaine.

Circulating Levels of Hydrogen Sulfide (H2S) in Patients with Age-Related Diseases: A Systematic Review and Meta-Analysis

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter that promotes multiple biological effects in many organs and tissues. An imbalanced biosynthesis of H₂S has been observed in animal models of age-related pathological conditions. However, the results from human studies are inconsistent. We performed a systematic review with meta-analysis of studies searched in Medline, Embase, Scopus, and CENTRAL databases. We included observational studies on patients with age-related diseases showing levels of H₂S in blood, plasma, or serum. All the analyses were carried out with R software. 31 studies were included in the systematic review and 21 in the meta-analysis. The circulating levels of H₂S were significantly reduced in patients with progressive, chronic, and degenerative diseases compared with healthy people (standardized mean difference, SMD: -1.25; 95% confidence interval, CI: -1.98; -0.52). When we stratified results by type of disorder, we observed a significant reduction in circulating levels of H₂S in patients with vascular disease (e.g., hypertension) (SMD: -1.32; 95% CI: -2.43; -0.22) or kidney disease (SMD: -2.24; 95% CI: -4.40; -0.08) compared with the control group. These results could support the potential use of compounds targeting the "H₂S system" to slow down the progression of many diseases in the elderly.

Plasma Homocysteine (Hcy) Concentration Functions as a Predictive Biomarker of SPECT-Evaluated Post-Ischemic Hyperperfusion in Acute Ischemic Stroke

Introduction

Homocysteine (Hcy) concentration has been reported to be associated with ischemic stroke. In this study, we aimed to investigate the potential of plasma Hcy in the prediction of post-ischemic hyperperfusion in AIS patients, which was diagnosed with the single-photon emission computed tomography (SPECT) method.

Methods

A total of 112 ischemic stroke patients were recruited in this study. According to whether the patients were subjected to post-ischemic hyperperfusion, all recruited subjects were divided into a post-ischemic hyperperfusion (+) group (N=48) and post-ischemic hyperperfusion (-) group (N=64). The basic demographical data, clinicopathological data and laboratory biochemical data were collected and compared. Level of homocysteine (Hcy) and cystatin-C (Cys-C) and their potential as predictive biomarker are also investigated.

Results

No significant differences were spotted between the post-ischemic hyperperfusion group (+) and post-ischemic hyperperfusion (-) group in respect to the basic demographical and clinicopathological data. And the serum Hcy levels were lower in the post-ischemic hyperperfusion (+) group. Moreover, ROC analysis indicated significant relationships between Hcy levels and the onset of post-ischemic hyperperfusion.

Conclusion

In conclusion, we validated that the plasma Hcy concentration can be used as a predictive biomarker of SPECT-evaluated post-ischemic hyperperfusion in patients suffering from acute ischemic stroke.

A one-step aptasensor for ultrasensitive detection of lung cancer marker homocysteine based on multifunctional carbon nanotubes by square-wave voltammetry

In this work, a one-step aptasensor for ultrasensitive detection of homocysteine (HCY) is developed based on multifunctional carbon nanotubes, which is magnetic multi-walled carbon nanotubes (Fe₃O₄@MWCNTs) combined with the aptamer (Apt) for HCY (Fe₃O₄@MWCNTs-Apt). Fe₃O₄@MWCNTs-Apt have multiple functions as follows. (1) Apt immobilized could selectively capture all target molecules HCY in the sample; (2) Magnetic Fe₃O₄ nanoparticles could separate all target molecules HCY captured by Apt from the sample substrate to eliminate the background interference and achieve one-step preparation of the aptasensor; And (3), MWCNTs with good electrical conductivity become a new electrode surface, construct a three-dimensional electrode surface network, make the electron transfer easier and thus then enhance the signal response. Results show that there is a good linear relationship between peak current of square-wave voltammetry (SWV) and HCY concentration in the range of 0.01 μmol/L-1 μmol/L, with a limit of detection (LOD) 0.002 μmol/L. And, selectivity, reproducibility, precision and accuracy are all satisfactory. In addition, it could be applied to the detection of HCY in the plasma of lung cancer patients successfully, suggesting that this one-step aptasensor for HCY has a potential in practical clinical applications.

Computational insights of excited state intramolecular proton transfer (ESIPT) based fluorescent detection and imaging of γ-glutamytranspeptidase activity

γ-Glutamytranspeptidase (GGT) is an important tumor biomarker that widely appears in the tumor cells. Therefore, accurate imaging and detection of GGT activity in live cells, serum and pathological cells grasp great importance for the diagnosis, management, and treatment of cancer. Herein, 2-(2-hydroxyl-phenyl)-6-chloro-4-(3H)-quinazolinone (HPQ) is considered as the fluorophore probe for the detection of GGT activity, which is known for the typical mechanism of excited-state intramolecular proton transfer (ESIPT). All the simulations adopted to evaluate the sensing mechanism were carried out via DFT and TDDFT calculations at CAM-B3LYP/TZVP level of theory. The emission properties of HPQ and HPQ-TD are thoroughly studied to understand the photoinduced electron transfer (PET) and excited state intramolecular proton transfer (ESIPT) process. The results reveal that the fluorescence quenching of HPQ (enol form) is assigned to the PET process, whereas the large Stokes shift in fluorescence emission of HPQ (keto form) is related with ESIPT mechanism. The obtained results are further cross validated by frontier molecular orbital (FMO) analysis, geometric analysis, and potential energy curve (PEC) scanning. Our calculations provide powerful evidence for the ESIPT based sensing mechanism of HPQ (keto-enol form) for GGT activity.

Methionine restriction constrains lipoylation and activates mitochondria for nitrogenic synthesis of amino acids

Methionine restriction (MR) provides metabolic benefits in many organisms. However, mechanisms underlying the MR-induced effect remain incompletely understood. Here, we show in the budding yeast S. cerevisiae that MR relays a signal of S-adenosylmethionine (SAM) deprivation to adapt bioenergetic mitochondria to nitrogenic anabolism. In particular, decreases in cellular SAM constrain lipoate metabolism and protein lipoylation required for the operation of the tricarboxylic acid (TCA) cycle in the mitochondria, leading to incomplete glucose oxidation with an exit of acetyl-CoA and α-ketoglutarate from the TCA cycle to the syntheses of amino acids, such as arginine and leucine. This mitochondrial response achieves a trade-off between energy metabolism and nitrogenic anabolism, which serves as an effector mechanism promoting cell survival under MR.

Comprehensive Metabolic Tracing Reveals the Origin and Catabolism of Cysteine in Mammalian Tissues and Tumors

Cysteine plays critical roles in cellular biosynthesis, enzyme catalysis, and redox metabolism. The intracellular cysteine pool can be sustained by cystine uptake or de novo synthesis from serine and homocysteine. Demand for cysteine is increased during tumorigenesis for generating glutathione to deal with oxidative stress. While cultured cells have been shown to be highly dependent on exogenous cystine for proliferation and survival, how diverse tissues obtain and use cysteine in vivo has not been characterized. We comprehensively interrogated cysteine metabolism in normal murine tissues and cancers that arise from them using stable isotope 13C1-serine and 13C6-cystine tracing. De novo cysteine synthesis was highest in normal liver and pancreas and absent in lung tissue, while cysteine synthesis was either inactive or downregulated during tumorigenesis. In contrast, cystine uptake and metabolism to downstream metabolites was a universal feature of normal tissues and tumors. However, differences in glutathione labeling from cysteine were evident across tumor types. Thus, cystine is a major contributor to the cysteine pool in tumors, and glutathione metabolism is differentially active across tumor types.

SIGNIFICANCE

Stable isotope 13C1-serine and 13C6-cystine tracing characterizes cysteine metabolism in normal murine tissues and its rewiring in tumors using genetically engineered mouse models of liver, pancreas, and lung cancers.

Influence of Cysteine 440 on the Active Site Properties of 3-Deoxy-d-Arabino-Heptulosonate 7-Phosphate Synthase in Mycobacterium tuberculosis (MtDAHPS)

The shikimate pathway, which produces aromatic amino acids and key intermediates, is critical to the viability of the tuberculosis-causing pathogen Mycobacterium tuberculosis. The enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) catalyzes the first committed step of this pathway and possesses regulatory functions. Its active site contains two cysteinyls: one (Cys₈₇) bound to a metal ion, while the other (Cys₄₄₀) is in proximity to the first but is located on a connecting loop. This arrangement seemingly appeared as a disulfide linkage. However, Cys₄₄₀ is not metal binding, and its positioning indicates that it could collapse the disulfide linkage. Hence, its potential role may be more than simply structural support of the active site fold. Using a multiscale computational approach, molecular dynamics (MD) simulations, and DFT-based calculations, the influence of Cys₄₄₀ on the active site properties has been investigated. MD simulations reveal an unusually long disulfide bond, more than 3.0 Å, whereas DFT calculations identified two stable active site conformers in the triplet and quintet spin states. Analysis of group spin density distribution identified antiferromagnetic coupling in each conformer, which suggests their relatively low potential energy and stable conformations. The conformer in the triplet spin state could favor enzyme reactivity due to its low HOMO-LUMO energy gap. In addition, reduction of the Cys₄₄₀ thiolate group results in collapse of the active site metal-ligand configuration with large exothermicity. Hence, Cys₄₄₀ could activate and inactivate the enzyme. For the first time, the study revealed the role of Cys₄₄₀ as being vital for the catalytic activity of the enzyme rather than solely for the structural stabilization of its active site. Thus, the findings may lead to a novel basis for antituberculosis drug design and development that would disrupt the contributions of the Cys₄₄₀.

N-Acetyl Cysteine Restores the Diminished Activity of the Antioxidant Enzymatic System Caused by SARS-CoV-2 Infection: Preliminary Findings

SARS-CoV-2 infects type II pneumocytes and disrupts redox homeostasis by overproducing reactive oxygen species (ROS). N-acetyl cysteine (NAC) is a precursor of the synthesis of glutathione (GSH) and it restores the loss of redox homeostasis associated to viral infections. The aim of the study is to evaluate the effect of the treatment with NAC on the enzymatic antioxidant system in serum from patients infected by SARS-CoV-2. We evaluated the enzymatic activities of thioredoxin reductase (TrxR), glutathione peroxidase (GPx), -S-transferase (GST), and reductase (GR) by spectrophotometry and the concentrations of the glutathione (GSH), total antioxidant capacity (TAC), thiols, nitrites (NO₂^-), and lipid peroxidation (LPO) in serum. The activity of the extracellular super oxide dismutase (ecSOD) was determined by native polyacrylamide gels, and 3-nitrotyrosine (3-NT) was measured by ELISA. A decrease in the activities of the ecSOD, TrxR, GPx, GST GR, (p = 0 ≤ 0.1), and the GSH, TAC, thiols, and NO₂^- (p ≤ 0.001) concentrations and an increase in LPO and 3-NT (p = 0.001) concentrations were found in COVID-19 patients vs. healthy subjects. The treatment with NAC as an adjuvant therapy may contribute to a reduction in the OS associated to the infection by SARS-CoV-2 through the generation of GSH. GSH promotes the metabolic pathways that depend on it, thus contributing to an increase in TAC and to restore redox homeostasis.

Interference of altered plasma trace elements profile with hyperhomocysteinemia and oxidative stress damage to insulin secretion dysfunction in Psammomys obesus: focus on the selenium

The objective of this study is to investigate the relationship between altered plasma trace elements, particularly selenium (Se), with Hyper-homocysteinemia (HhCys) as a predictive factor of insulin secretion dysfunction. The study is carried out on adult Psammomys obesus, divided in 4 experimental groups: (I) Normoglycemic/Normoinsulinemic; (II) Normoglycemic/Hyperinsulinemic; (III) Hyperglycaemic/Hyperinsulinemic and (IV) Hyperglycaemic/Insulin deficiency with ketoacidosis. The data showed that a drastic depletion of Se plasma levels is positively correlated with HhCys (>15 µmol/L; p < .001), concomitantly with decreased GPx activity, GSH levels, and GSH/GSSG ratio in group IV both in plasma and liver. In contrast, SOD activity is increased (p ≤ .001) in group IV both in plasma and liver. However, plasma Cu and Mn levels increased, while plasma Zn levels decreased in group IV (p < .001). Our study confirms the increase of plasma hCys levels seemed to be a major contributing factor to antioxidant capacities and alters the availability of selenium metabolism by interference with homocysteine synthesis in the insulin secretion deficiency stage.

Atherosclerotic Cardiovascular Disease in Inflammatory Bowel Disease: The Role of Chronic Inflammation and Platelet Aggregation

Background and Objectives: Atherosclerosis is one of inflammatory bowel disease's most significant cardiovascular manifestations. This research aimed to examine the relationship between biochemical, haemostatic, and immune parameters of atherosclerosis and ulcerative colitis patients and its relationship to platelet aggregation. Materials and Methods: A clinical, observational cross-sectional study was performed, during which the tested parameters were compared in the experimental and control groups. The patients were divided into four groups. The first group had 25 patients who had ulcerative colitis and atherosclerosis. The second group included 39 patients with ulcerative colitis without atherosclerosis. The third group comprised 31 patients suffering from atherosclerosis without ulcerative colitis, and the fourth group comprised 25 healthy subjects. Results: In our study, we registered statistically higher levels of inflammatory markers like SE, CRP, Le, fecal calprotectin, TNF-α, and IL-6, as well as the higher value of thrombocytes and thrombocyte aggregation in the group of patients with ulcerative colitis compared to the control group. Lower levels of total cholesterol and LDL were also recorded in patients with ulcerative colitis and atherosclerosis and ulcerative colitis without atherosclerosis compared to healthy control. Triglyceride and remnant cholesterol were higher in patients with ulcerative colitis and atherosclerosis when compared to patients with ulcerative colitis and healthy control but lower than in patients with atherosclerosis only. Conclusions: Several inflammatory markers and platelet aggregation could be good discrimination markers for subjects with ulcerative colitis with the highest risk of atherosclerosis.

Post-prandial response in hepatopancreas and haemolymph of Penaeus monodon fed different diets. Omics insights into glycoconjugate metabolism, energy utilisation, chitin biosynthesis, immune function, and autophagy

Raw materials or bioactive ingredients trigger mechanisms to assimilate nutrients and activate metabolic pathways that promote growth, immune function, or energy storage. Our understanding of these processes at a molecular level remains limited in aquaculture, especially in shrimp. Here, hepatopancreas proteomics and haemolymph metabolomics were used to investigate the post-prandial response of black tiger shrimps (Penaeus monodon) fed a conventional fishmeal diet (FM); a diet supplemented with the microbial biomass Novacq™ (NV); krill meal (KM); or, fasted (FS). Using FM as a control, a 2-fold change in abundance threshold was implemented to determine the significance of proteins and metabolites. NV fed shrimp showed preference for energy derived from carbohydrates indicated by a strong signature of glycoconjugate metabolism and activation of the amino- and nucleotide sugar metabolic pathway. KM activated the glyoxylate and dicarboxylate pathway that denoted shrimp preference for lipidic energy. KM also influenced energy generation by the TCA cycle inferred from higher abundance of the metabolites succinic semialdehyde, citric acid, isocitrate, alpha ketoglutarate and ATP and downregulation of the enzyme isocitrate dehydrogenase that catalyses oxidative decarboxylation of isocitrate. FS shrimp displayed down-regulation of oxidative phosphorylation and resorted to internal lipid reserves for energy homeostasis displaying a strong signature of autophagy. Pyrimidine metabolism was the preferred energy strategy in this group. Our study also provided evidence that during fasting or consumption of specific ingredients, shrimp share common pathways to meet their energy requirements, however, the intensity at which these pathways were impacted was diet dependent.

A single-wavelength excited NIR fluorescence probe for distinguishing GSH/H2S and Cys/Hcy in living cells and zebrafish through separated dual-channels

Biothiols and hydrogen sulfide, as critical sulfur-containing reactive substances, serve essential functions in various human pathological processes, making it challenging to simultaneously distinguish them due to their similar reactivity and structures (-SH). Here, we rationalized the development of a single-wavelength excitation near-infrared (NIR) fluorescence probe, FC-NBD, for distinguishing GSH/H₂S and Cys/Hcy by separated fluorescence dual channels. In this probe, FC-NBD, composed of coumarin-benzopyrylium derivatives linked with nitro benzoxadiazole (NBD) via ether bonds, could quantitatively and selectively distinguish GSH/H₂S and Cys/Hcy with a low limit of detection (LOD) of 0.199/0.177 μM and 0.106/0.076 μM, respectively. As expected, under single-wavelength excitation (470 nm), FC-NBD demonstrated distinctly separable green and NIR fluorescence emissions towards Cys/Hcy at 550 and 660 nm, but only exhibited a noticeable NIR fluorescence emission towards GSH/H₂S at 660 nm. Moreover, FC-NBD could simultaneously visualize and discriminate GSH/H₂S and Cys/Hcy in living cells as well as zebrafish through green and NIR channels at a single excitation wavelength.

A rapid and selective methionine oxidative modification strategy

Considering the fact that site-selective late-stage diversification of peptides and proteins remains a challenge for biochemistry, strategies targeting low-abundance natural amino acids need to be further developed. As an extremely oxidation-sensitive and low-abundance amino acid, methionine emerges as a promising target for chemo- and site-selective modification. Herein we report an efficient and highly selective modification on methionine residues by one-pot O- and N-transfer reaction, generating sulfoximine-modified peptides with near-perfect conversion within 10 min. Moreover, the great tolerance to other natural amino acids has been demonstrated in reactions with various peptide substrates. To demonstrate the generality of this protocol, we have modified natural peptides and obtained sulfoximination products with high conversion rates. This methodology provides a novel strategy as the expansion of the methionine-based peptide functionalization toolbox.

Spectroscopic analysis of the mammalian enzyme cysteine dioxygenase

l-Cysteine (Cys) is an essential building block for the synthesis of new proteins and serves as a precursor for several biologically important sulfur-containing molecules, such as coenzyme A, taurine, glutathione, and inorganic sulfate. However, organisms must tightly regulate the concentration of free Cys, as elevated levels of this semi-essential amino acid can be extremely harmful. The non-heme iron enzyme cysteine dioxygenase (CDO) serves to maintain the proper levels of Cys by catalyzing its oxidation to cysteine sulfinic acid. Crystal structures of resting and substrate-bound mammalian CDO revealed two surprising structural motifs in the first and second coordination spheres of the Fe center. The first is the existence of a neutral three histidine (3-His) facial triad that coordinates the Fe ion, as opposed to an anionic 2-His-1-carboxylate facial triad that is typically observed in mononuclear non-heme Fe(II) dioxygenases. The second unusual structural feature exhibited by mammalian CDO is the presence of a covalent crosslink between the sulfur of a Cys residue and an ortho-carbon of a tyrosine residue. Spectroscopic studies of CDO have provided invaluable insights into the roles that these unusual features play with regards to substrate Cys and co-substrate O2 binding and activation. In this chapter, we summarize results obtained from electronic absorption, electron paramagnetic resonance, magnetic circular dichroism, resonance Raman, and Mössbauer spectroscopic studies of mammalian CDO carried out in the last two decades. Pertinent results obtained from complementary computational studies are also briefly summarized.

Quercetin modulates the liver metabolic profile in a chronic unpredictable mild stress rat model based on metabolomics technology

Depression is the most prevalent psychiatric disease, and its pathogenesis is still unclear. Currently, studies on the pathogenesis of depression are mainly focused on the brain. The liver can modulate brain function via the liver-brain axis, indicating that the liver plays an important role in the development of depression. This study aims to explore the protective effect of quercetin against chronic unpredictable mild stress (CUMS)-induced metabolic changes and the corresponding mechanisms in the rat liver based on untargeted metabolomics technology. In this study, 96 male rats were divided into six groups: control, different doses of quercetin (10 mg per kg bw or 50 mg per kg bw), CUMS, and CUMS + different doses of quercetin. After 8 weeks of CUMS modeling, the liver samples were collected for metabolomics analysis. A total of 17 altered metabolites were identified, including D-glutamic acid, S-adenosylmethionine, lithocholylglycine, L-homocystine, prostaglandin PGE2, leukotriene E4, cholic acid, 5-methyltetrahydrofolic acid, taurochenodeoxycholic acid, S-adenosylhomocysteine, deoxycholic acid, folic acid, L-methionine, leukotriene C5, estriol-17-glucuronide, PE, and PC, indicating that methionine metabolism, bile acid metabolism, and phosphatidylcholine biosynthesis are the major pathways involved in CUMS-induced hepatic metabolic disorders. Hepatic methylation damage may play a role in the pathophysiology of depression, as evidenced by the first discovery of the abnormality of hepatic methionine metabolism. Abnormal changes in hepatic bile acids may provide stronger evidence for depression pathogenesis involving the microbiota-gut-brain axis, suggesting that the liver is involved in depression development and may be a treatment target. The quercetin treatment alleviated the CUMS-induced liver metabolism disorder, suggesting that quercetin may protect against depression by regulating liver metabolism.

Photoacoustic/fluorescence dual-modality cyanine-based probe for real-time imaging of endogenous cysteine and in situ diagnosis of cervical cancer in vivo

Cysteine (Cys), one of cellular biothiols in the organism, is associated with many diseases, such as Parkinson's disease, Alzheimer's disease, liver damage, rheumatoid arthritis, and cancer. However, activatable fluorescence/photoacoustic (FL/PA) probes for non-invasive, real-time, and deep imaging of Cys in vivo are still lacking, and this hinders the diagnosis of Cys-related diseases. Herein, we designed and synthesized a novel activated FL/PA dual-modality cyanine-base probe (FP₇₀₀) for real-time detection of Cys. The probe FP₇₀₀ was established with near-infrared emissive dye cyanin as the fluorophore, linking with 2, 4-dinitrobenzenesulfonyl group as the recognition moiety for Cys. Using the FP₇₀₀, we found that the FP₇₀₀ exhibited intensive "turn-on" FL/PA signals under the excitation of 700 nm, which realized noninvasive in vivo detection of exogenous Cys. Significantly, FP₇₀₀ accurately detected endogenous Cys though the FL/PA dual-mode imaging technology in tumor-bearing mice and obtain 3D PA diagnostic images with deep penetration depth and spatial resolution. Thus, the new dual-modality probe FP₇₀₀ has advantage of high potential for deep tumor diagnosis of Cys in vivo, which may provide a new approach for the detection of cervical cancer and identification of its potential therapeutic targets.

Hydrogen sulfide production during early yeast fermentation correlates with volatile sulfur compound biogenesis but not thiol release

Yeasts undergo intensive metabolic changes during the early stages of fermentation. Previous reports suggest the early production of hydrogen sulfide (H2S) is associated with the release of a range of volatile sulfur compounds (VSCs), as well as the production of varietal thiol compounds 3-sulfanylhexan-1-ol (3SH) and 3-sulfanylhexyl acetate (3SHA) from six-carbon precursors, including (E)-hex-2-enal. In this study, we investigated the early H2S potential, VSCs/thiol output, and precursor metabolism of 11 commonly used laboratory and commercial Saccharomyces cerevisiae strains in chemically defined synthetic grape medium (SGM) within 12 h after inoculation. Considerable variability in early H2S potential was observed among the strains surveyed. Chemical profiling suggested that early H2S production correlates with the production of dimethyl disulfide, 2-mercaptoethanol, and diethyl sulfide, but not with 3SH or 3SHA. All strains were capable of metabolizing (E)-hex-2-enal, while the F15 strain showed significantly higher residue at 12 h. Early production of 3SH, but not 3SHA, can be detected in the presence of exogenous (E)-hex-2-enal and H2S. Therefore, the natural variability of early yeast H2S production contributes to the early output of selected VSCs, but the threshold of which is likely not high enough to contribute substantially to free varietal thiols in SGM.

Comparative effects of dietary methionine and cysteine supplementation on redox status and intestinal integrity in immunologically challenged-weaned pigs

Sulfur-containing amino acids such as methionine and cysteine play critical roles in immune system and redox status. A body of evidence shows that metabolic aspects of supplemented Met and Cys may differ in the body. Therefore, the study aimed to investigate the effects of dietary Met and Cys supplementation in immunologically challenged weaned pigs. Forty weaned piglets (6.5 ± 0.3 kg) were randomly allocated to five treatment groups. The treatment included: (1) sham-challenged control (SCC), (2) challenged control (CC), (3) MET (CC + 0.1% _DL-Met), (4) CYS (CC + 0.1% _L-Cys), and (5) MET + CYS (CC + 0.1% _DL-Met + 0.1% _L-Cys). On day 7, all pigs were intramuscularly injected with either Escherichia coli O55:B5 lipopolysaccharides (LPS) or phosphate-buffered saline. Blood, liver, and jejunum samples were analyzed for immune response and redox status. The CC group had lower (P < 0.05) villus surface area and higher (P < 0.05) flux of 4-kDa fluorescein isothiocyanate dextran (FD4) than the SCC group. A lower (P < 0.05) glutathione (GSH) concentration was observed in the jejunum of pigs in the CC group than those in the SCC group. Dietary Cys supplementation increased (P < 0.05) villus surface area, GSH levels, and reduced (P < 0.05) the flux of FD4 in the jejunum of LPS-challenged pigs. Dietary Met supplementation enhanced (P < 0.05) hepatic GSH content. Pigs challenged with LPS in the MET group had lower serum IL-8 concentration than those in the CC group. There was a Met × Cys interaction (P < 0.05) in serum IL-4 and IL-8 concentrations, and Trolox equivalent antioxidant capacity. Dietary _L-Cys supplementation restored intestinal integrity and GSH levels that were damaged by lipopolysaccharides administration. Dietary _DL-Met supplementation improved hepatic GSH and reduced systemic inflammatory response, but antagonistic interaction with dietary _L-Cys supplementation was observed in the inflammatory response and redox status.

Phosphocholine cytidylyltransferase MoPct1 is crucial for vegetative growth, conidiation, and appressorium-mediated plant infection by Magnaporthe oryzae

Phosphatidylcholine (PC) plays crucial biological roles in eukaryotic cells. In Saccharomyces cerevisiae, apart from phosphatidylethanolamine (PE) methylation pathway, PC is also synthesized via CDP-choline pathway. Phosphocholine cytidylyltransferase Pct1 is the rate-limiting enzyme to catalyze the conversion from phosphocholine to CDP-choline in this pathway. Here, we report the identification and functional characterization of an ortholog of the budding yeast PCT1 in Magnaporthe oryzae, named MoPCT1. Targeted gene deletion mutants of MoPCT1 were impaired in vegetative growth, conidiation, appressorium turgor accumulation and cell wall integrity. Also, the mutants were severely compromised in appressorium-mediated penetration, infectious growth and pathogenicity. Western blot analysis revealed that cell autophagy was activated by the deletion of MoPCT1 under nutrient-rich conditions. Moreover, we found several key genes in PE methylation pathway, such as MoCHO2, MoOPI3, and MoPSD2, were significantly up-regulated in the ΔMopct1 mutants, indicating that a pronounced compensation effect exists between the two PC biosynthesis pathways in M. oryzae. Interestingly, in the ΔMopct1 mutants, histone H3 was hypermethylated and expression levels of several methionine cycling-related genes were significantly up-regulated, suggesting that MoPCT1 is involved in histone H3 methylation and methionine metabolism. Taken together, we conclude that the phosphocholine cytidylyltransferase coding gene MoPCT1 plays important roles in vegetative growth, conidiation and appressorium-mediated plant infection by M. oryzae.

Hydrogen Sulfide Regulates Macrophage Function in Cardiovascular Diseases

Significance: Hydrogen sulfide (H₂S) is an endogenous gasotransmitter that plays a vital role in immune system regulation. Recently, the regulation of macrophage function by H₂S has been extensively and actively recognized. Recent Advances: The mechanisms by which endogenous H₂S controls macrophage function have attracted increasing attention. The generation of endogenous H₂S from macrophages is mainly catalyzed by cystathionine-γ-lyase. H₂S is involved in the macrophage activation and inflammasome formation, which contributes to macrophage apoptosis, adhesion, chemotaxis, and polarization. In addition, H₂S has redox ability and interacts with reactive oxygen species to prevent oxidative stress. Moreover, H₂S epigenetically regulates gene expression. Critical Issues: In this article, the generation of endogenous H₂S in macrophages and its regulatory effect on macrophage function are reviewed. In addition, the signal transduction targeting macrophages by H₂S is also addressed. Finally, the potential therapeutic effect of H₂S on macrophages is discussed. Future Directions: Further experiments are required to explore the involvement of endogenous H₂S in the regulation of macrophage function in various physiological and pathophysiological processes and elucidate the mechanisms involved. Regarding the clinical translation of H₂S, further exploration of the application of H₂S in inflammation-related diseases is needed. Antioxid. Redox Signal. 38, 45-56.

DFT insights into the mechanism of O2 activation catalyzed by a structural and functional model of cysteine dioxygenase with tris(2-pyridyl)methane-based ligand architecture

Cysteine dioxygenation is an important step in the metabolism of toxic L-cysteine (Cys) in the human body, carried out by cysteine dioxygenase enzyme (CDO). The disruption of this process is found to elicit neurological health issues. This work reports a computational investigation of mechanistic aspects of this reaction, using a recently reported tris(2-pyridyl)methane-based biomimetic model complex of CDO. The computed results indicate that, the initial SO2 bond formation process is the slowest step in the S-dioxygenation process, possessing an activation barrier of 12.7 kcal/mol. The remaining steps were found to be downhill requiring very small activation energies. The transition states were found to undergo spin crossover between triplet and quintet states, while the singlet surface remained unstable throughout the entire reaction. In essence, the mechanistic scheme and multistate reactivity pattern together with the relatively small computed rate-limiting activation barrier as well as the exothermic formation energy demonstrate that the model complex is an efficient biomimetic CDO model. In addition, the study also substantiates the involvement of Fe(IV)oxido intermediates in the mechanism of S-dioxygenation by the chosen model complex. The insights derived from the O₂ activation process might pave way for development of more accurate CDO model catalysts that might be capable of even more efficiently mimicking the geometric, spectroscopic and functional features of the CDO enzyme.

On-demand therapeutic delivery of hydrogen sulfide aided by biomolecules

Hydrogen sulfide (H₂S), known as the third gasotransmitter, exerts various physiological functions including cardiac protection, angiogenesis, anti-inflammatory, and anti-cancer capability. Given its promising therapeutic potential as well as severe perniciousness if improper use, the sustained and tunable H₂S delivery systems are highly required for H₂S-based gas therapy with enhanced bioactivity and reduced side effects. To this end, a series of stimuli-responsive compounds capable of releasing H₂S (termed H₂S donors) have been designed over the past two decades to mimic the endogenous generation of H₂S and elucidate the biological functions. Further to improve the stability of H₂S donors and achieve the targeted delivery, various delivery systems have been constructed. In this review, we focus on the recent advances of an emerging subset, biomolecular-based H₂S delivery systems, which combine H₂S donors with biomolecular vectors including polysaccharide, peptide, and protein. We demonstrated their basic structures, building strategies, and therapeutic applications respectively to unfold their inherent merits endued by biomolecules including biocompatibility, biodegradability as well as expansibility. The varied development potentials of biomolecular-based H₂S delivery systems based on their specific properties are also discussed. At the end, brief future outlooks and upcoming challenges are presented as well.

Transcriptomic analysis reveals the key role of histone deacetylation via mediating different phytohormone signalings in fiber initiation of cotton

Background

Histone deacetylation is one of the most important epigenetic modifications and plays diverse roles in plant development. However, the detailed functions and mechanisms of histone deacetylation in fiber development of cotton are still unclear. HDAC inhibitors (HDACi) have been commonly used to study the molecular mechanism underlying histone deacetylation or to facilitate disease therapy in humans through hindering the histone deacetylase catalytic activity. Trichostatin A (TSA)—the most widely used HDACi has been extensively employed to determine the role of histone deacetylation on different developmental stages of plants.

Results

Through in vitro culture of ovules, we observed that exogenous application of TSA was able to inhibit the fiber initiation development. Subsequently, we performed a transcriptomic analysis to reveal the underlying mechanisms. The data showed that TSA treatment resulted in 4209 differentially expressed genes, which were mostly enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, photosynthesis, and carbon metabolism pathways. The phytohormone signal transduction pathways harbor the most differentially expressed genes. Deeper studies showed that some genes promoting auxin, Gibberellic Acid (GA) signaling were down-regulated, while some genes facilitating Abscisic Acid (ABA) and inhibiting Jasmonic Acid (JA) signaling were up-regulated after the TSA treatments. Further analysis of plant hormone contents proved that TSA significantly promoted the accumulation of ABA, JA and GA₃.

Conclusions

Collectively, histone deacetylation can regulate some key genes involved in different phytohormone pathways, and consequently promoting the auxin, GA, and JA signaling, whereas repressing the ABA synthesis and signaling to improve the fiber cell initiation. Moreover, the genes associated with energy metabolism, phenylpropanoid, and glutathione metabolism were also regulated by histone deacetylation. The above results provided novel clues to illuminate the underlying mechanisms of epigenetic modifications as well as related different phytohormones in fiber cell differentiation, which is also very valuable for the molecular breeding of higher quality cotton.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00840-4.

Arazyme in combination with dietary carbohydrolases influences odor emission and gut microbiome in growing-finishing pigs

This study evaluated the effects of supplementing feed with arazyme and dietary carbohydrolases derived from invertebrate gut-associated symbionts on the noxious gas emissions, gut microbiota, and host-microbiome interactions of pigs. Here, 270 and 260 growing pigs were assigned to control and treatment groups, respectively. The tested feed additives contained a mixture of arazyme (2,500,000 Unit/kg) and synergetic enzymes, xylanase (200,000 Unit/kg) and mannanase (200,000 Unit/kg), derived from insect gut-associated symbionts in a 7.5:1:1 ratio. The control group was fed a basal diet and the treatment group was fed the basal diet supplemented with 0.1 % enzyme mixture (v/v) for 2 months. Odorous gases were monitored in ventilated air from tested houses. Fecal samples were collected from steel plate under the cage at the completion of the experiment to determine chemical composition, odor emissions, and bacterial communities. There was a significant decrease in the concentration of NH₃ (22.5 vs. 11.2 ppm; P < 0.05), H₂S (7.35 vs. 3.74 ppm; P < 0.05), trimethylamine (TMA) (0.066 vs. 0.001 ppm; P < 0.05), and p-cresol (0.004 ppm vs. 0 ppm; P < 0.05) at 56 d in treatment group compared with the control group. Moreover, fecal analysis results showed that exogenous enzyme supplementation caused a reduction in VFAs and indole content with approximately >60 % and 72.7 %, respectively. The result of gas emission analysis showed that NH₃ (9.9 vs. 5.3 ppm; P < 0.05) and H₂S (5.8 vs. 4.1 ppm; P < 0.05) were significantly reduced in the treatment group compared to the control group. The gut microbiota of the treatment group differed significantly from that of the control group, and the treatment group altered predicted metabolic pathways, including sulfur and nitrogen related metabolism, urea degradation. The results demonstrated that supplementing feed with arazyme with dietary carbohydrolases effectively controls noxious gas emissions and improves health and meat quality of pigs.

Sulfur amino acid supplementation displays therapeutic potential in a C. elegans model of Duchenne muscular dystrophy

Mutations in the dystrophin gene cause Duchenne muscular dystrophy (DMD), a common muscle disease that manifests with muscle weakness, wasting, and degeneration. An emerging theme in DMD pathophysiology is an intramuscular deficit in the gasotransmitter hydrogen sulfide (H₂S). Here we show that the C. elegans DMD model displays reduced levels of H₂S and expression of genes required for sulfur metabolism. These reductions can be offset by increasing bioavailability of sulfur containing amino acids (L-methionine, L-homocysteine, L-cysteine, L-glutathione, and L-taurine), augmenting healthspan primarily via improved calcium regulation, mitochondrial structure and delayed muscle cell death. Additionally, we show distinct differences in preservation mechanisms between sulfur amino acid vs H₂S administration, despite similarities in required health-preserving pathways. Our results suggest that the H₂S deficit in DMD is likely caused by altered sulfur metabolism and that modulation of this pathway may improve DMD muscle health via multiple evolutionarily conserved mechanisms.

A C. elegans model of Duchenne muscular dystrophy reveals a potential role for disrupted sulfur metabolism in the disease and thus the therapeutic potential of sulfur amino acid supplementation.

Methionine and total homocysteine in hypertensive patients with renal excretory dysfunction

The role of the kidneys in the metabolism and homeostasis of sulfur-containing amino acids is great, so the levels of methionine (Met), total homocysteine (tHcy) and their ratios can be of diagnostic value in chronic kidney disease (CKD), in a course of the arterial hypertension (AH). The aim of the study was to evaluate the Met/tHcy ratio in hypertensive patients with CKD. We used blood plasma of 76 patients aged 40-75 years with AH and the excretory dysfunction of the kidneys; subgroups: 1 - with proteinuria (n=37); 2 - without proteinuria with glomerular filtration rate (GFR) < 90 ml/min/1.73 m2 (n=39) and comparison group 3 - patients with AH without renal excretory dysfunction (n=28). Significantly lower Met levels were in subgroup 1. THcy levels were higher in subgroups 1 and 2 than in group 3. The Met/tHcy ratio revealed differences in subgroups 1 and 2 vs group 3. No differences were found in Arg and Lys levels. Positive correlations of the Met/tHcy ratio with the number of erythrocytes, but not with the level of hemoglobin, were revealed. In the ROC analysis, the cut-off points for the Met/tHcy ratio compared to group 3 were 3.08 for subgroup 1 and 3.36 for subgroup 2. With the progression of CKD, there is an increase in the levels of tHcy in the blood, and a decrease in the content of Met. A decrease in GFR, especially in a case with proteinuria, is accompanied by a decrease in the level of Met. The Met/tHcy ratio above 3.36 can be considered as the minimum of the balance between these sulfur-containing amino acids contents in a blood necessary for hypertensive patients with CKD.

Effect of folic acid supplementation on the change of plasma S-adenosylhomocysteine level in Chinese hypertensive patients: a randomized, double-blind, controlled clinical trial

The relationship between folic acid and S-adenosylhomocysteine (SAH) is controversial. This study aims to explore the effect of different doses of folic acid supplementation on SAH levels in hypertensive patients and the modification of methylene-tetrahydrofolate reductase (MTHFR) C677T gene polymorphism. A randomized, double-blind, controlled clinical trial was conducted. Hypertensive patients aged 45-75 years without a history of stroke and cardiovascular disease were selected, who were randomly assigned to one of 8 dose groups. This trial has been registered with Trial Number: ChiCTR1800016135. In the total population, folic acid supplementation of 0.4-2.0 mg/day had no effect on SAH level (β = 0.47, 95% CI: -0.86-1.79, p = 0.491), while folic acid supplementation of 2.4 mg/day significantly increased SAH level (β = 1.93, 95% CI: 0.22-3.64, p = 0.027). Stratified analysis found that MTHFR C677T genotype CC supplemented with 2.4 mg/day folic acid had no effect on SAH level (β = 0.30, 95% CI: -2.74-3.34, p = 0.847), while CT and TT genotype supplemented with 2.4 mg/day folic acid showed a significant increase in SAH level (CT: β = 2.98, 95% CI: 0.34-5.62, p = 0.027; TT: β = 3.00, 95% CI: -0.51-6.51, p = 0.095; CT combined with TT: β = 2.99, 95% CI: 0.90-5.09, p = 0.005). In conclusion, supplementation of 2.4 mg/day folic acid can lead to increased SAH levels, especially in MTHFR C677T genotype CT and TT.

Deodorized Garlic Decreases Oxidative Stress Caused by Lipopolysaccharide in Rat Heart through Hydrogen Sulfide: Preliminary Findings

Deodorized garlic (DG) may favor the activity of the antioxidant enzymes and promote the synthesis of hydrogen sulfide (H₂S). The objective was to test if DG favors an increase in H₂S and if it decreases the oxidative stress caused by lipopolysaccharide (LPS) in rat hearts. A total of 24 rats were divided into 4 groups: Group 1 control (C), Group 2 LPS, Group 3 DG, and Group 4 LPS plus DG. The cardiac mechanical performance (CMP), coronary vascular resistance (CVR), and oxidative stress markers, such as total antioxidant capacity (TAC), glutathione (GSH), selenium (Se), lipid peroxidation (LPO), thiols, hydrogen sulfide (H₂S), and the activities and expressions of thioredoxin reductase (TrxR), glutathione peroxidase (GPx), and glutathione-S-transferase (GST), cystathionine synthetase (CBS), cystathionine γ-lyase (CTH), iNOS, and eNOS-p, were analyzed in the heart. Infarct zones in the cardiac tissue were present (p = 0.01). The CMP and CVR decreased and increased (p ≤ 0.05), TAC, GSH, H₂S, NO, thiols, and GST activity (p ≤ 0.01) decreased, and LPO and iNOS increased (p ≤ 0.05). The activities and expressions of TrxR, GPx, eNOS-p, CTH, and CBS (p ≤ 0.05) decreased with the LPS treatment; however, DG normalized this effect. DG treatment decreases heart damage caused by LPS through the cross-talk between the H₂S and NO systems.

Michael acceptor-dependent pro-oxidative intervention against angiogenesis by [6]-dehydroshogaol, a pungent constituent of ginger

Accumulating evidence suggests that ginger and its pungent constituents harbor a wealth of biological activities including cancer chemopreventive activity. However, relatively few researches focus on [6]-dehydroshogaol (6-DHS) compared with other ginger pungent constituents such as [6]-shogaol (6S). In this work, we selected three ginger compounds, 6-DHS, 6S and [6]-paradol (6P) differentiated by the presence and number of the Michael acceptor units, to probe structural basis and mechanism of 6-DHS in inhibiting angiogenesis, a key step for tumor growth and metastasis. It was found that their antiangiogenic activity is significantly dependent on the presence and number of Michael acceptor units. Benefiting from its two Michael acceptor units, 6-DHS is the most potent inhibitor of thioredoxin reductase and depletor of glutathione, thereby being the most active generator of reactive oxygen species, which is responsible for its strongest ability to inhibit angiogenesis. This work highlights 6-DHS being a Michael acceptor-dependent pro-oxidative angiogenesis inhibitor.