H2S Signaling Research Articles

Hydrogen sulfide promotes hypocotyl elongation via increasing cellulose content and changing the arrangement of cellulose fibrils in alfalfa.

Hydrogen sulfide (H2S) is known to have positive physiological functions in plant growth, but limited data are available on its influence on cell walls. Here, we demonstrate a novel mechanism by which H2S regulates the biosynthesis and deposition of cell wall cellulose in alfalfa (Medicago sativa). Treatment with NaHS was found to increase the length of epidermal cells in the hypocotyl, and transcriptome analysis indicated that it caused the differential expression of numerous of cell wall-related genes. These differentially expressed genes were directly associated with the biosynthesis of cellulose and hemicellulose, and with the degradation of pectin. Analysis of cell wall composition showed that NaHS treatment increased the contents of cellulose and hemicellulose, but decreased the pectin content. Atomic force microscopy revealed that treatment with NaHS decreased the diameter of cellulose fibrils, altered the arrangement of the fibrillar bundles, and increased the spacing between the bundles. The dynamics of cellulose synthase complexes (CSCs) were closely related to cellulose synthesis, and NaHS increased the rate of mobility of the particles. Overall, our results suggest that the H2S signal enhances the plasticity of the cell wall by regulating the deposition of cellulose fibrils and by decreasing the pectin content. The resulting increases in cellulose and hemicellulose contents lead to cell wall expansion and cell elongation.

Hydrogen sulfide mediates DNA methylation to enhance osmotic stress tolerance in Setaria italica L.

DNA methylation is an important form of epigenetic modification. It has a vital role in regulating plant growth and development, and also participates in plant response to various stresses. In recent years, hydrogen sulfide (H2S) has been shown to have similar functions as DNA methylation, but crosstalk between DNA methylation and H2S in the acquisition of drought resistance is unclear. In this study, foxtail millet (Setaria italica L.), a drought-resistant model crop, was selected as the experimental material to explore the subtle relationship between H2S and DNA methylation. The quantitative real-time (qRT)-PCR, bisulfite sequencing PCR (BSP), DNA methyltransferase (DNMT) activity detection and other techniques were used to analyze the differences of millet seedlings under osmotic stress, before and after H2S treatment. Osmotic stress induced the transcriptional expression and activity of key enzymes in H2S biosynthesis which regulated the accumulation of endogenous H2S. Physiological concentration of H2S (50 μM) can effectively alleviate the decrease of total DNMT activity and transcription level caused by osmotic stress, while the effective inhibitor of H2S biosynthesis, hydroxylamine (HA), can aggravate this change. Furthermore, transcription factors (TFs) responsive to both ‘osmotic stress’ and ‘H2S signal’ were screened. Six of them were selected to conduct further BSP analysis on seven CpG islands in their promoter regions. The results showed that, with H2S treatment, two CpG islands were hypermethylated, two were not, and three exhibited insensitivity to H2S. H2S signals may improve osmotic stress tolerance of foxtail millet by mediating DNA methylation.

Crosstalk between Hydrogen Sulfide and Other Signal Molecules Regulates Plant Growth and Development.

Hydrogen sulfide (H2S), once recognized only as a poisonous gas, is now considered the third endogenous gaseous transmitter, along with nitric oxide (NO) and carbon monoxide (CO). Multiple lines of emerging evidence suggest that H2S plays positive roles in plant growth and development when at appropriate concentrations, including seed germination, root development, photosynthesis, stomatal movement, and organ abscission under both normal and stress conditions. H2S influences these processes by altering gene expression and enzyme activities, as well as regulating the contents of some secondary metabolites. In its regulatory roles, H2S always interacts with either plant hormones, other gasotransmitters, or ionic signals, such as abscisic acid (ABA), ethylene, auxin, CO, NO, and Ca2+. Remarkably, H2S also contributes to the post-translational modification of proteins to affect protein activities, structures, and sub-cellular localization. Here, we review the functions of H2S at different stages of plant development, focusing on the S-sulfhydration of proteins mediated by H2S and the crosstalk between H2S and other signaling molecules.

Chemico-Proteomics Reveal the Enhancement of Salt Tolerance in an Invasive Plant Species via H2S Signaling.

H2S is a small molecule known to have multiple signaling roles in animals. Recently, evidence shows that H2S also has signaling functions in plants; however, the role of H2S in invasive plants is unknown. Spartina alterniflora is a typical invasive species growing along the beaches of southern China. A physiological comparison proves that S. alterniflora is highly tolerant to salinity stress compared with the native species Cyperus malaccensis. To decipher the mechanism that enables S. alterniflora to withstand salinity stress, a chemico-proteomics analysis was performed to examine the salt stress response of the two species; an inhibitor experiment was additionally designed to investigate H2S signaling on salinity tolerance in S. alterniflora. A total of 86 proteins belonging to nine categories were identified and differentially expressed in S. alterniflora exposed to salt stress. Moreover, the expression level of enzymes responsible for the H2S biosynthesis was markedly upregulated, indicating the potential role of H2S signaling in the plant’s response to salt stress. The results suggested that salt triggered l-CD enzyme activity and induced the production of H2S, therefore upregulating expression of the antioxidants ascorbate peroxidase, superoxide dismutase, and S-nitrosoglutathione reductase, which mitigates damage from reactive nitrogen species. Additionally, H2S reduced the potassium efflux, thereby sustaining intracellular sodium/potassium ion homeostasis and enhancing S. alterniflora salt tolerance. These findings indicate that H2S plays an important role in the adaptation of S. alterniflora to saline environments, which provides greater insight into the function of H2S signaling in the adaptation of an invasive plant species.

H2S as a potential defense against COVID-19?

The outbreak of COVID-19 pneumonia caused by a new coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) is posing a global health emergency and has led to more than 380,000 deaths worldwide. The cell entry of SARS-CoV-2 depends on two host proteins angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). There is currently no vaccine available and also no effective drug for the treatment of COVID-19. Hydrogen sulfide (H2S) as a novel gasotransmitter has been shown to protect against lung damage via its anti-inflammation, antioxidative stress, antiviral, prosurvival, and antiaging effects. In light of the research advances on H2S signaling in biology and medicine, this review proposed H2S as a potential defense against COVID-19. It is suggested that H2S may block SARS-CoV-2 entry into host cells by interfering with ACE2 and TMPRSS2, inhibit SARS-CoV-2 replication by attenuating virus assembly/release, and protect SARS-CoV-2-induced lung damage by suppressing immune response and inflammation development. Preclinical studies and clinical trials with slow-releasing H2S donor(s) or the activators of endogenous H2S-generating enzymes should be considered as a preventative treatment or therapy for COVID-19.

Trophoblast H2S Maintains Early Pregnancy via Regulating Maternal-Fetal Interface Immune Hemostasis.

Dysregulated immune hemostasis occurs in unexplained recurrent spontaneous abortion (URSA). Synthesized by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), hydrogen sulfide (H2S) promotes regulatory T-cell differentiation and regulates immune hemostasis; yet, its role in URSA is elusive. To determine if H2S plays a role in early pregnancy and if dysregulated H2S signaling results in recurrent spontaneous abortion. First trimester placenta villi and decidua were collected from normal and URSA pregnancies. Protein expression was examined by immunohistochemistry and immunoblotting. Human trophoblast HTR8/SVneo and JEG3 cells were treated with H2S donors; HTR8/SVneo cells were transfected with CBS ribonucleic acid interference (RNAi) or complementary deoxyribonucleic acid. Cell migration and invasion were determined by transwell assays; trophoblast transcriptomes were determined by RNA sequencing (RNA-seq). Wild-type, CBS-deficient, and CBA/J × DBA/2 mice were treated with CBS and CSE inhibitors or H2S donors to determine the role of H2S in early pregnancy in vivo. CBS and CSE proteins showed cell-specific expressions, but only CBS decreased in the villous cytotrophoblast in URSA versus normal participants. H2S donors promoted migration and invasion and MMP-2 and VEGF expression in human placenta trophoblast cells that contain SV40 viral deoxyribonucleic acid sequences (HTR8/SVneo) and human placenta trophoblast cells (JEG3 cells), similar to forced CBS expression in HTR8/SVneo cells. The CBS-responsive transcriptomes in HTR8/SVneo cells contained differentially regulated genes (ie, interleukin-1 receptor and prostaglandin-endoperoxide synthase 2) that are associated with nuclear factor-κB-mediated inflammatory response. In vivo, dysregulated CBS/H2S signaling significantly increased embryonic resorption and decidual T-helper 1/T-helper 2 imbalance in mice, which was partially rescued by H2S donors. CBS/H2S signaling maintains early pregnancy, possibly via regulating maternal-fetal interface immune hemostasis, offering opportunities for H2S-based immunotherapies for URSA.

Mitigation of chromium (VI) toxicity by additional sulfur in some vegetable crops involves glutathione and hydrogen sulfide

Toxic metals cause substantial reduction in crop yields every year. Therefore, worldwide scientific efforts are being made to reduce such losses in crop productivity by using certain chemical protectants such as nutrients like sulfur (S), hydrogen sulfide (H2S), glutathione (GSH), etc. Therefore in this study, we have tested potential of additional S, along with probable involvement of H2S and GSH in mitigating hexavalent chromium (CrVI) toxicity in tomato, pea and brinjal seedlings. Chromium (VI) decreased shoot and root length, endogenous H2S, and cell viability due to greater Cr accumulation that led to cell death in roots. Chromium (VI) enhanced oxidative stress markers i.e. superoxide radical, hydrogen peroxide, lipid peroxidation and protein oxidation due to down-regulation in ascorbate-glutathione cycle. However, additional S reversed toxic effect of Cr(VI). Chromium (VI) slightly stimulated enzymes of glutathione biosynthesis. Besides this, the results also showed that addition of buthionine sulphoximine (BSO, synthetic inhibitor of glutathione biosynthesis) interestingly further enhanced Cr(VI) toxicity even in the presence of additional S. But this effect of BSO was reversed by the addition of GSH. Interestingly, hydroxylamine (HA, synthetic inhibitor of cysteine desulfhydrase) had also further increased Cr(VI) toxicity even in the presence of additional S but sodium hydrosulfide (NaHS, an H2S donor) reversed this effect. Furthermore, ameliorative behaviour of NaHS against Cr(VI) toxicity was reversed by the hypotaurine (HT, a H2S scavenger). All together results suggested that additional S involved GSH and H2S in mitigating Cr(VI) toxicity in studied vegetables, in which GSH acted downstream of H2S signal.

Dysregulated hydrogen sulfide metabolism links aberrant neuronal stress responses and neurodegeneration in Huntington's disease

Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays central roles in a myriad of physiological processes ranging from response to oxidative stress and transcriptional regulation. Hydrogen sulfide is synthesized endogenously from the semi‐essential amino acid cysteine via the reverse transsulfuration pathway. Thus disrupted cysteine metabolism may also lead to aberrant H2S signaling. One of the modes by which hydrogen sulfide signals is by a posttranslational modification designated as sulfhydration/persulfidation, which occurs on reactive cysteine residues on target proteins, where the reactive SH group is converted to an SSH group. Sulfhydration is a highly prevalent modification which modifies the structure and/or activity of target proteins. Research on H2S and persulfidation is still in its infancy. We show here that H2S is generated in response to stress stimuli such as Golgi stress and oxidative stress in neurons, which modulates sulfhydration levels to modulate signaling pathways. We further show that these cytoprotective stress responses are compromised in striatal cell culture model and the R6/2 and Q175 mouse models of Huntington’s disease (HD). We have shown previously that the biosynthetic enzyme for cysteine and H2S in neurons, cystathionine g‐lyase (CSE) is depleted in HD and mediates neurodegeneraton. HD is a neurodegenerative disease which is triggered by expansion of polyglutamine repeats in the protein huntingtin, which causes it to aggregate and elicit multi‐system toxicity. Restoring H2S balance in cells mitigates neuronal dysfunction in neurodegenerative diseases such as HD. A screen for regulators of the transsulfuration pathway has resulted in identification of compounds that modulate cysteine balance and disease progression in HD.Support or Funding InformationUnited States Public Health Service (USPHS) grants DA000266 and MH18501 to S.H.S.

Hydrogen Sulfide Impairs Meiosis Resumption in Xenopuslaevis Oocytes.

The role of hydrogen sulfide (H2S) is addressed in Xenopus laevis oocytes. Three enzymes involved in H2S metabolism, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase, were detected in prophase I and metaphase II-arrested oocytes and drove an acceleration of oocyte meiosis resumption when inhibited. Moreover, meiosis resumption is associated with a significant decrease in endogenous H2S. On another hand, a dose-dependent inhibition was obtained using the H2S donor, NaHS (1 and 5 mM). NaHS impaired translation. NaHS did not induce the dissociation of the components of the M-phase promoting factor (MPF), cyclin B and Cdk1, nor directly impacted the MPF activity. However, the M-phase entry induced by microinjection of metaphase II MPF-containing cytoplasm was diminished, suggesting upstream components of the MPF auto-amplification loop were sensitive to H2S. Superoxide dismutase and catalase hindered the effects of NaHS, and this sensitivity was partially dependent on the production of reactive oxygen species (ROS). In contrast to other species, no apoptosis was promoted. These results suggest a contribution of H2S signaling in the timing of amphibian oocytes meiosis resumption.

Hydrogen Sulfide Metabolism and Signaling in the Tumor Microenvironment.

Hydrogen sulfide (H2S), while historically perceived merely as a toxicant, has progressively emerged as a key regulator of numerous processes in mammalian physiology, exerting its signaling function essentially through interaction with and/or modification of proteins, targeting mainly cysteine residues and metal centers. As a gaseous signaling molecule that freely diffuses across aqueous and hydrophobic biological milieu, it has been designated the third 'gasotransmitter' in mammalian physiology. H2S is synthesized and detoxified by specialized endogenous enzymes that operate under a tight regulation, ensuring homeostatic levels of this otherwise toxic molecule. Indeed, imbalances in H2S levels associated with dysfunctional H2S metabolism have been growingly correlated with various human pathologies, from cardiovascular and neurodegenerative diseases to cancer. Several cancer cell lines and specimens have been shown to naturally overexpress one or more of the H2S-synthesizing enzymes. The resulting increased H2S levels have been proposed to promote cancer development through the regulation of various cancer-related processes, which led to the interest in pharmacological targeting of H2S metabolism. Herein are summarized some of the key observations that place H2S metabolism and signaling pathways at the forefront of the cellular mechanisms that support the establishment and development of a tumor within its complex and challenging microenvironment. Special emphasis is given to the mechanisms whereby H2S helps shaping cancer cell bioenergetic metabolism and affords resistance and adaptive mechanisms to hypoxia.

Exercise Training Promotes Cardiac Hydrogen Sulfide Biosynthesis and Mitigates Pyroptosis to Prevent High-Fat Diet-Induced Diabetic Cardiomyopathy.

Obesity increases the risk of developing diabetes and subsequently, diabetic cardiomyopathy (DMCM). Reduced cardioprotective antioxidant hydrogen sulfide (H2S) and increased inflammatory cell death via pyroptosis contribute to adverse cardiac remodeling and DMCM. Although exercise training (EX) has cardioprotective effects, it is unclear whether EX mitigates obesity-induced DMCM by increasing H₂S biosynthesis and mitigating pyroptosis in the heart. C57BL6 mice were fed a high-fat diet (HFD) while undergoing treadmill EX for 20 weeks. HFD mice developed obesity, hyperglycemia, and insulin resistance, which were reduced by EX. Left ventricle pressure-volume measurement revealed that obese mice developed reduced diastolic function with preserved ejection fraction, which was improved by EX. Cardiac dysfunction was accompanied by increased cardiac pyroptosis signaling, structural remodeling, and metabolic remodeling, indicated by accumulation of lipid droplets in the heart. Notably, EX increased cardiac H₂S concentration and expression of H₂S biosynthesis enzymes. HFD-induced obesity led to features of type 2 diabetes (T2DM), and subsequently DMCM. EX during the HFD regimen prevented the development of DMCM, possibly by promoting H₂S-mediated cardioprotection and alleviating pyroptosis. This is the first report of EX modulating H₂S and pyroptotic signaling in the heart.

The Benefits of Macromolecular/Supramolecular Approaches in Hydrogen Sulfide Delivery: A Review of Polymeric and Self-Assembled Hydrogen Sulfide Donors.

Significance: Cell homeostasis and redox balance are regulated in part by hydrogen sulfide (H2S), a gaseous signaling molecule known as a gasotransmitter. Given its biological roles, H2S has promising therapeutic potential, but controlled delivery of this reactive and hazardous gas is challenging due to its promiscuity, rapid diffusivity, and toxicity at high doses. Macromolecular and supramolecular drug delivery systems are vital for the effective delivery of many active pharmaceutical ingredients, and H2S stands to benefit greatly from the tunable physical, chemical, and pharmacokinetic properties of polymeric and/or self-assembled drug delivery systems. Recent Advances: Several types of H2S-releasing macro- and supramolecular materials have been developed in the past 5 years, and the field is expanding quickly. Slow-releasing polymers, polymer assemblies, polymer nano- and microparticles, and self-assembled hydrogels have enabled triggered, sustained, and/or localized H2S delivery, and many of these materials are more potent in biological assays than analogous small-molecule H2S donors. Critical Issues: H2S plays a role in a number of (patho)physiological processes, including redox balance, ion channel regulation, modulation of inducible nitric oxide synthase, angiogenesis, blood pressure regulation, and more. Chemical tools designed to (i) deliver H2S to study these processes, and (ii) exploit H2S signaling pathways for treatment of diseases require control over the timing, rate, duration, and location of release. Future Directions: Development of new material approaches for H2S delivery that enable long-term, triggered, localized, and/or targeted delivery of the gas will enable greater understanding of this vital signaling molecule and eventually expedite its clinical application.

Abstract P1109: Cholesterol Regulation of Hydrogen Sulfide-Mediated Vasodilation

Hydrogen sulfide (H 2 S) is produced within the vascular wall by cystathionine γ-lyase (CSE). CSE is expressed throughout the vascular tree however, the sensitivity to H 2 S-induced dilation in small resistance size arteries (<100 μm) is greater than the dilation sensitivity in large arteries (>300 μm). Although H 2 S can induce vasodilation in different size arteries, it is not clear how H 2 S signaling mechanisms differ in large and small arteries, garnering H 2 S-induced dilation prominent and important in small resistance arteries. We previously demonstrated that within endothelial cells, H 2 S-mediated vasodilation involves activation of transient receptor potential cation channel subfamily V member 4 (TRPV4)-dependent Ca 2+ influx and large conductance Ca 2+ -activated potassium (BK) channel. Based on previous reports that membrane cholesterol negatively regulates TRPV4 mobility and BK activity, we hypothesized that H 2 S-mediated vasodilation is diminished by membrane cholesterol and that lower sensitivity in large arteries might be due to higher levels of membrane cholesterol in endothelial cells. Isolated pressurized mesenteric arteries (300-380 μm) were treated luminally with vehicle (HEPES) or the cholesterol-depleting agent, methyl β cyclodextran (MBCD, 100 μM) and exposed to H 2 S donor, NaHS (10 μM). Analysis of H 2 S-induced dilation (expressed as % Ca 2+ free diameter) showed that MBCD treatment significantly enhanced H 2 S-mediated vasodilation (vehicle: 1.2% ± 1.2, MBCD: 8.9% ± 2.3, p = 0.012, n = 5 animals/group). Additionally, mesenteric arteries of different orders were luminally loaded with the fluorescent cholesterol-binding agent, filipin III (20 μg/ml, ex/em: 405/461 nm) the endothelial glycocalyx marker DyLight 594-tomato lectin (20 μg/ml, ex/em: 561/613 nm) and the nuclei stain SYTOX green (ex/em: 488/518 nm). Analysis of endothelial membrane cholesterol content (filipin III /tomato lectin fluorescence) was significantly greater in larger arteries (2 nd order: 1.019 ± 0.158, 5 th order: 0.344 ± 0.179, p = 0.0054, n = 3-5 animals/group). These studies suggest that higher membrane cholesterol decreases H 2 S-mediated vasodilation.

Hydrogen Sulfide: Recent Progression and Perspectives for the Treatment of Diabetic Nephropathy.

Diabetic kidney disease develops in approximately 40% of diabetic patients and is a major cause of chronic kidney diseases (CKD) and end stage kidney disease (ESKD) worldwide. Hydrogen sulfide (H2S), the third gasotransmitter after nitric oxide (NO) and carbon monoxide (CO), is synthesized in nearly all organs, including the kidney. Though studies on H2S regulation of renal physiology and pathophysiology are still in its infancy, emerging evidence shows that H2S production by renal cells is reduced under disease states and H2S donors ameliorate kidney injury. Specifically, aberrant H2S level is implicated in various renal pathological conditions including diabetic nephropathy. This review presents the roles of H2S in diabetic renal disease and the underlying mechanisms for the protective effects of H2S against diabetic renal damage. H2S may serve as fundamental strategies to treat diabetic kidney disease. These H2S treatment modalities include precursors for H2S synthesis, H2S donors, and natural plant-derived compounds. Despite accumulating evidence from experimental studies suggests the potential role of the H2S signaling pathway in the treatment of diabetic nephropathy, these results need further clinical translation. Expanding understanding of H2S in the kidney may be vital to translate H2S to be a novel therapy for diabetic renal disease.

Hydrogen sulfide perturbs mitochondrial bioenergetics and triggers metabolic reprogramming in colon cells

Unlike most other tissues, the colon epithelium is exposed to high levels of H2S derived from gut microbial metabolism. H2S is a signaling molecule that modulates various physiological effects. It is also a respiratory toxin that inhibits complex IV in the electron transfer chain (ETC). Colon epithelial cells are adapted to high environmental H2S exposure as they harbor an efficient mitochondrial H2S oxidation pathway, which is dedicated to its disposal. Herein, we report that the sulfide oxidation pathway enzymes are apically localized in human colonic crypts at the host-microbiome interface, but that the normal apical-to-crypt gradient is lost in colorectal cancer epithelium. We found that sulfide quinone oxidoreductase (SQR), which catalyzes the committing step in the mitochondrial sulfide oxidation pathway and couples to complex III, is a critical respiratory shield against H2S poisoning. H2S at concentrations ≤20 μm stimulated the oxygen consumption rate in colon epithelial cells, but, when SQR expression was ablated, H2S concentrations as low as 5 μm poisoned cells. Mitochondrial H2S oxidation altered cellular bioenergetics, inducing a reductive shift in the NAD+/NADH redox couple. The consequent electron acceptor insufficiency caused uridine and aspartate deficiency and enhanced glutamine-dependent reductive carboxylation. The metabolomic signature of this H2S-induced stress response mapped, in part, to redox-sensitive nodes in central carbon metabolism. Colorectal cancer tissues and cell lines appeared to counter the growth-restricting effects of H2S by overexpressing sulfide oxidation pathway enzymes. Our findings reveal an alternative mechanism for H2S signaling, arising from alterations in mitochondrial bioenergetics that drive metabolic reprogramming.

Hydrous heating experiments at 130 °C yield insights into the occurrence of hydrogen sulfide and light alkanes in natural gas reservoirs

Improved understanding of the origin of produced volatiles from conventional reservoirs and unconventional source rocks is critical for petroleum exploration and production. A series of hydrous heating experiments using two immature Type II siliciclastic source rocks, Pennsylvanian Turner Mine shale (TMS) and Devonian New Albany Shale (NAS), at 130 °C over one to two years were conducted to assess gas generation at low temperature. Elemental sulfur (ES) was added to the NAS samples to evaluate the role of sulfur on thermochemical sulfate reduction (TSR). The produced volatile composition was investigated in situ using Raman spectroscopy at the end of the heating experiments. Results show that the two source rocks yield different types and concentrations of volatiles. Only CH4 and CO2 were detected following hydrous heating of the TMS source rock in contrast to CH4, C2H6, C3H8, and CO2 which were observed in experiments using NAS. Variations in the produced volatiles are likely the result of compositional differences within the respective source rock organic matter. Experiments involving ES show strong H2S signals that are likely due to the formation of H2S from the reaction of ES with water at 130 °C. H2S signals correlate with a greater relative concentration of CH4 and CO2 compared to experiments where ES was not added, on a time-normalized basis. The correlation between the presence of H2S and an increase in CH4 and CO2 concentration could indicate the occurrence of TSR. Here we propose that H2S in siliciclastic shale can be generated in the presence of ES at low temperatures via both disproportionation of ES into H2S and SO42−, and TSR. Our findings from this study provide experimental evidence that may aid efforts to interpret the origin of H2S in low-temperature sedimentary basins.

The hydrogen sulfide signal enhances seed germination tolerance to high temperatures by retaining nuclear COP1 for HY5 degradation

Seed germination is a critical stage during the initiation of the plant lifecycle and is strongly affected by endogenous phytohormones and environmental stress. High temperature (HT) upregulates endogenous abscisic acid (ABA) to suppress seed germination, and ABA-INSENSITIVE 5 (ABI5) is the key positive regulator in the ABA signal-mediated modulation of seed germination. In plants, hydrogen sulfide (H2S) is a small gas messenger that participates in multiple physiological processes, but its role in seed germination thermotolerance has not been thoroughly elucidated to date. In this study, we found that H2S enhanced the seed germination rate under HT. Moreover, HT accelerates the efflux of the E3 ligase CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) from the nucleus to the cytoplasm, which results in increased nuclear accumulation of ELONG HYPCOTYL 5 (HY5) to activate the expression of ABI5 and thereby suppress seed germination. However, the H2S signal reversed the HT effect, as characterized by increased COP1 in the nucleus, which resulted in increased degradation of HY5 and reduced expression of ABI5 and thereby enhanced the seed germination thermotolerance. Thus, our findings reveal a novel role for the H2S signal in the modulation of seed germination thermotolerance through the nucleocytoplasmic partitioning of COP1 and the downstream HY5 and ABI5 pathways.

Central Administration of Hydrogen Sulfide Alleviates Rodent Angiotensin II Hypertension

IntroductionActivation of autonomic neural pathways plays a significant role in pathogenesis of hypertension (HTN). Hydrogen sulfide (H2S) is an endogenous neuro‐ and immunomodulatory molecule that is reportedly reduced in both rodent and human HTN. However, central role of H2S in HTN is not well understood. We hypothesized that chronic intracerebroventricular (ICV) infusion of sodium hydrosulfide (NaHS), an H2S donor, will alleviate rodent angiotensin II (Ang II) HTN.MethodsAdult male Sprague Dawley rats were implanted with radiotelemetry transmitters (DSI) in the descending aorta. Following baseline BP measurements, rats were randomly divided into three groups: (i) ICV NaHS; (ii) HTN; and (iii) ICV NaHS‐treated HTN rats. HTN was induced by chronic infusion of Ang II (200 ng/kg/min s.c.) for four weeks using mini‐osmotic pumps. ICV NaHS (30 nmol/h) or ICV saline was administered simultaneously with s.c. Ang II or saline infusion. At endpoint, H2S levels were measured in plasma samples of all rats.ResultsAt week four, mean arterial pressure (MAP) was significantly reduced in the ICV NaHS‐treated HTN group when compared with HTN group (104±7 vs. 166±5 mmHg, respectively; P< 0.01). This was associated with a lower MAP at night in the ICV NaHS‐treated HTN vs. HTN group (Delta MAP from day to night: 15.29±4 vs. 31.37±17 mmHg, respectively), suggesting reduced sympathetic drive following treatment with NaHS. Interestingly, this also reflected in significantly higher plasma H2S levels in the ICV NaHS‐treated HTN vs. HTN group (0.070±0.000 AU vs. 0.067±0.000 AU, respectively; P<0.05).ConclusionThese results support our hypothesis that alterations in central H2S signaling are associated with HTN, as centrally administered NaHS alleviated rodent Ang II HTN via reduction of sympathetic tone at night.Support or Funding InformationTUBITAK 2214‐A and UF CVM.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Probiotics Ameliorate Gut‐Microbial Dysbiosis, Intestinal Permeability, Systemic Inflammation, and Skeletal Muscle Dysfunction in Cystathionine‐β‐synthase‐Deficient Mice

Recent studies have reported that dietary supplementation of probiotics is a novel approach for enhancing skeletal development and metabolism in both humans and animals. However, the precise role of probiotics in regulating skeletal muscle mass at the cellular and molecular levels in mice still needs to be clarified. Here we show that altered gut‐microbiota eubiosis, systemic inflammation and skeletal muscle dysfunction caused by hydrogen sulfide deficiency and whether the intragastric administration of probiotics (GSL#5) could retard H2S deficiency‐related skeletal muscle defects. To test this hypothesis, we employed 8‐week‐old female wild‐type (WT), cystathionine‐beta‐synthase heterozygote knockout (CBS+/−), and CBS+/− mice supplemented with probiotics (GSL#5) at the dosage of 1×109 CFU every other day through oral gavage for 6 weeks. In the murine model, H2S deficiency (CBS+/− mice) increased gut permeability, and upregulated the inflammatory cytokines TNFα (TNF), and IL‐17 in the blood and the skeletal muscle. Further, the gut microbiota is significantly altered in CBS‐deficient mice as assessed by the Denaturing gradient gel electrophoresis (DGGE) analysis. We documented that long non‐coding RNA‐PVT1 (lncRNA‐PVT1) is, indeed, upregulated in the soleus muscles of CBS‐deficient mice (4.2 fold), as assessed by RT2 lncRNA qPCR Assay. The mechanistic study shows that depressed H2S signaling stimulates the transcription factor C/EBP‐α binding to the promoter of lncRNA‐PVT1 and promotes the expression of lncRNA‐PVT1. Using an electrophoretic mobility shift assay and chromatin immunoprecipitations, we identified that lncRNA‐PVT1 interacts with TNFAIP3 interacting protein 1, TNIP1, leading to the acetylation of NF‐κB (P65 subunit) activity in the soleus muscle of CBS‐deficient mice. Further, activation of P65 region of NF‐κB transcriptionally upregulates atrogin‐1, MuRF‐1 expression. Overexpression of lncRNA‐PVT1 in cultured C2C12 muscle cell lines stimulates an increase in MuRF‐1 (2.3‐fold) and atrogin‐1 (3.7‐fold) expression. In addition, systemic delivery of synthetic lncRNA‐PVT1 in control mice causes the myofibers to undergo atrophy. Gene knockout of lncRNA‐PVT1 in CBS‐deficient mice attenuates atrophy of the myofibers and muscle wasting. Overall, administration of probiotics in CBS‐deficient mice reverses the gut‐microbiota dysbiosis and preserves skeletal muscle mass. In conclusion, our findings provide novel evidence that the administration of probiotics could balance the gut‐microbiota homeostasis as well as skeletal muscle function by modulating systemic inflammation in H2S‐deficient miceSupport or Funding InformationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Role of hydrogen sulfide in the musculoskeletal system.

Hydrogen sulfide (H2S) has been known as a gasotransmitter, and it contributes to various physiological and pathological processes. Multiple enzymes such as cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-Mercaptopyruvate sulfurtransferase (MST) produce endogenous H2S, and these are differentially expressed in the various tissue systems including the skeletal system. However, abnormal H2S production is associated with deregulation of the signaling cascade and imbalanced tissue homeostasis. Several studies have previously provided evidence showing the essential regulatory action of H2S in skeletal homeostasis. In this review, we have emphasized the novel function of H2S in both bone and skeletal muscle anabolism, in particular. Additionally, we also reviewed the molecular and epigenetic basis of H2S signaling in bone development and skeletal muscle function.