Mapping the Endothelial Cell S-Sulfhydrome Highlights the Crucial Role of Integrin Sulfhydration in Vascular Function

Chemoselective Proteomics, Zinc Fingers, and a Zinc(II) Model for H2S Mediated Persulfidation

The gasotransmitter hydrogen sulfide (H2S) is thought to be involved in the post-translational modification of cysteine residues to produce reactive persulfides. A persulfide-specific chemoselective proteomics approach with mammalian cells has identified a broad range of zinc finger (ZF) proteins as targets of persulfidation. Parallel studies with isolated ZFs show that persulfidation is mediated by ZnII, O2, and H2S, with intermediates involving oxygen- and sulfur-based radicals detected by mass spectrometry and optical spectroscopies. A small molecule ZnII complex exhibits analogous reactivity with H2S and O2, giving a persulfidated product. These data show that ZnII is not just a biological structural element, but also plays a critical role in mediating H2S-dependent persulfidation. ZF persulfidation appears to be a general post-translational modification and a possible conduit for H2S signaling. This work has implications for our understanding of H2S-mediated signaling and the regulation of ZFs in cellular physiology and development.

Analysis and characterization of sulfane sulfur

In the late 1970s, sulfane sulfur was defined as sulfur atoms covalently bound only to sulfur atoms. However, this definition was not generally accepted, as it was slightly vague and difficult to comprehend. Thus, in the early 1990s, it was defined as "bound sulfur," which easily converts to hydrogen sulfide upon reduction with a thiol-reducing agent. H2S-related bound sulfur species include persulfides (R-SSH), polysulfides (H2Sn, n ≥ 2 or R-S(S)nS-R, n ≥ 1), and protein-bound elemental sulfur (S0). Many of the biological effects currently associated with H2S may be attributed to persulfides and polysulfides. In the 20th century, quantitative determination of "sulfane sulfur" was conventionally performed using a reaction called cyanolysis. Several methods have been developed over the past 30 years. Current methods used for the detection of H2S and polysulfides include colorimetric assays for methylene blue formation, sulfide ion-selective or polarographic electrodes, gas chromatography with flame photometric or sulfur chemiluminescence detection, high-performance liquid chromatography analysis with fluorescent derivatization of sulfides, liquid chromatography with tandem mass spectrometry, the biotin switch technique, and the use of sulfide or polysulfide-sensitive fluorescent probes. In this review, we discuss the methods reported to date for measuring sulfane sulfur and the results obtained using these methods.

Hydrogen sulfide improves endothelial barrier function by modulating the ubiquitination degradation of KLF4 through TRAF7 S-sulfhydration in diabetic aorta

Anomalous vascular endothelium significantly contributes to various cardiovascular diseases. VE-cadherin plays a vital role in governing the endothelial barrier. Krüppel-like factor 4(KLF4), as a transcription factor, which binds the VE-cadherin promoter and enhances its transcription. Tumor necrosis factor receptor-associated factor 7 (TRAF7) is an E3 ubiquitin ligase that has been shown to modulate the degradation of KLF4. H2S can covalently modify cysteine residues on proteins through S-sulfhydration, thereby influencing the structure and functionality of the target protein. However, the role of S-sulfhydration on endothelial barrier integrity remains to be comprehensively elucidated. This study aims to investigate whether protein S-sulfhydration in the endothelium regulates endothelial integrity and its underlying mechanism. In this study, we observed that protein S-sulfhydration was reduced in the endothelium during diabetes and TRAF7 was the main target. Overexpression of TRAF7-Cys327 mutant could mitigate the endothelial barrier damage by weakening TRAF7 interaction with KLF4 and reducing ubiquitination degradation of KLF4. In conclusion, our research demonstrates that H2S plays a pivotal role in regulating S-sulfhydration of TRAF7 at Cys327. This regulation effectively inhibits the ubiquitin-mediated degradation of KLF4, resulting in an upregulation of VE-cadherin levels. This molecular mechanism contributes to the prevention of endothelial barrier damage.

Investigating the impact of protein S-sulfhydration modification on vascular diseases: A comprehensive review

The post-translational modification of cysteine through redox reactions, especially S-sulfhydration, plays a critical role in regulating protein activity, interactions, and spatial arrangement. This review focuses on the impact of protein S-sulfhydration on vascular function and its implications in vascular diseases. Dysregulated S-sulfhydration has been linked to the development of vascular pathologies, including aortic aneurysms and dissections, atherosclerosis, and thrombotic diseases. The H2S signaling pathway and the enzyme cystathionine γ-lyase (CSE), which is responsible for H2S generation, are identified as key regulators of vascular function. Additionally, potential therapeutic targets for the treatment of vascular diseases, such as the H2S donor GYY4137 and the HDAC inhibitor entinostat, are discussed. The review also emphasizes the antithrombotic effects of H2S in regulating platelet aggregation and thrombosis. The aim of this review is to enhance our understanding of the function and mechanism of protein S-sulfhydration modification in vascular diseases, and to provide new insights into the clinical application of this modification.

Effect of reactive oxygen, nitrogen, and sulfur species on signaling pathways in atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which fats, lipids, cholesterol, calcium, proliferating smooth muscle cells, and immune cells accumulate in the intima of the large arteries, forming atherosclerotic plaques. A complex interplay of various vascular and immune cells takes place during the initiation and progression of atherosclerosis. Multiple reports indicate that tight control of reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) production is critical for maintaining vascular health. Unrestricted ROS and RNS generation may lead to activation of various inflammatory signaling pathways, facilitating atherosclerosis. Given these deleterious consequences, it is important to understand how ROS and RNS affect the signaling processes involved in atherogenesis. Conversely, RSS appears to exhibit an atheroprotective potential and can alleviate the deleterious effects of ROS and RNS. Herein, we review the literature describing the effects of ROS, RNS, and RSS on vascular smooth muscle cells, endothelial cells, and macrophages and focus on how changes in their production affect the initiation and progression of atherosclerosis. This review also discusses the contribution of ROS, RNS, and RSS in mediating various post-translational modifications, such as oxidation, nitrosylation, and sulfation, of the molecules involved in inflammatory signaling.

Hydrogen Sulfide Signaling in the Tumor Microenvironment: Implications in Cancer Progression and Therapy

Significance: Cancer is a complex and heterotypic structure with a spatial organization that contributes to challenges in therapeutics. Enzymes associated with producing the gasotransmitter hydrogen sulfide (H2S) are differentially expressed in tumors. Indeed, critical and paradoxical roles have been attributed to H2S in cancer-promoting characteristics by targeting both cancer cells and their milieu. This review focuses on the evidence and knowledge gaps of H2S on the tumor redox microenvironment and the pharmacological effects of H2S donors on cancer biology. Recent Advances: Endogenous and pharmacological concentrations of H2S evoke different effects on the same cell type: physiological H2S concentrations have been associated with tumor development and progression. In contrast, pharmacological concentrations have been associated with anticancer effects. Critical Issues: The exact threshold between the promotion and inhibition of tumorigenesis by H2S is largely unknown. The main issues covered in this review include H2S-modulated signaling pathways that are critical for cancer cells, the potential effects of H2S on cellular components of the tumor microenvironment, temporal modulation of H2S in promoting or inhibiting tumor progression (similar to observed for inflammation), and pharmacological agents that modulate H2S and which could play a role in antineoplastic therapy. Future Directions: Given the complexity and heterogeneity of tumor composition, mechanistic studies on context-dependent pharmacological effects of H2S donors for cancer therapy are necessary. These studies must determine the critical signaling pathways and the cellular components involved to allow advances in the rational use of H2S donors as antineoplastic agents. Antioxid. Redox Signal. 40, 250-271.

Manganese Porphyrin-Containing Polymeric Micelles: A Novel Approach for Intracellular Catalytic Formation of Per/Polysulfide Species from a Hydrogen Sulfide Donor

Per/polysulfide species that are generated from endogenously produced hydrogen sulfide have critical regulatory roles in a wide range of cellular processes. However, the lack of delivery systems that enable controlled and sustained release of these unstable species in biological systems hinders the advancement of sulfide biology research, as well as the translation of knowledge to therapeutic applications. Here, a novel approach is developed to generate per/polysulfide species in cells by combining an H2 S donor and manganese porphyrin-containing polymeric micelles (MnPMCs) that catalyze oxidization of H2 S to per/polysulfide species. MnPMCs serve as a catalyst for H2 S oxidation in aerobic phosphate buffer. HPLC-MS/MS analysis reveals that H2 S oxidation by MnPMCs in the presence of glutathione results in the formation of glutathione-SnH (n = 2 and 3). Furthermore, co-treatment of human umbilical vein endothelial cells with the H2 S donor anethole dithiolethione and MnPMCs increases intracellular per/polysulfide levels and induces a proangiogenic response. Co-delivery of MnPMCs and an H2 S donor is a promising approach for controlled delivery of polysulfides for therapeutic applications.

Loss of cardiac mitochondrial complex I persulfidation impairs NAD+ homeostasis in aging

Protein persulfidation is a significant post-translational modification that involves addition of a sulfur atom to the cysteine thiol group and is facilitated by sulfide species. Persulfidation targets reactive cysteine residues within proteins, influencing their structure and/or function across various biological systems. This modification is evolutionarily conserved and plays a crucial role in preventing irreversible cysteine overoxidation, a process that becomes prominent with aging. While, persulfidation decreases with age, its levels in the aged heart and the functional implications of such a reduction in cardiac metabolism remain unknown. Here we interrogated the cardiac persulfydome in wild-type adult mice and age-matched mice lacking the two sulfide generating enzymes, namely cystathionine gamma lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3MST). Our findings revealed that cardiac persulfidated proteins in wild type hearts are less abundant compared to those in other organs, with a primary involvement in mitochondrial metabolic processes. We further focused on one specific target, NDUFB7, which undergoes persulfidation by both CSE and 3MST derived sulfide species. In particular, persulfidation of cysteines C80 and C90 in NDUFB7 protects the protein from overoxidation and maintains the complex I activity in cardiomyocytes. As the heart ages, the levels of CSE and 3MST in cardiomyocytes decline, leading to reduced NDUFB7 persulfidation and increased cardiac NADH/NAD+ ratio. Collectively, our data provide compelling evidence for a direct link between cardiac persulfidation and mitochondrial complex I activity, which is compromised in aging.

Hydrogen Sulfide and Functional Therapy: Novel Mechanisms from Epigenetics

Hydrogen sulfide (H2S) is a gasotransmitter with significant physiological effects, including anti-inflammatory properties, regulation of oxidative stress, and vasodilation, thus regulating body functions. Functional therapy involves using treatments that target the underlying cause of a disease, rather than simply treating symptoms. Epigenetics refers to changes in gene expression that occur through modifications to DNA, to the proteins that package DNA, or to noncoding RNA mechanisms. Recent research advances suggest that H2S may play a role in epigenetic regulation by altering DNA methylation patterns and regulating histone deacetylases, enzymes that modify histone proteins, or modulating microRNA mechanisms. These critical findings suggest that H2S may be a promising molecule for functional therapy in various diseases where epigenetic modifications are dysregulated. We reviewed the relevant research progress in this area, hoping to provide new insights into the epigenetic mechanisms of H2S. Despite the challenges of clinical use of H2S, future research may lead to the progress of new therapeutic approaches. Antioxid. Redox Signal. 40, 110-121.

Hydrogen sulfide attenuates atherosclerosis induced by low shear stress by sulfhydrylating endothelium NFIL3 to restrain MEST mediated endothelial mesenchymal transformation

BACKGROUND

Endothelial-mesenchymal transition (EndMT) induced by low shear stress plays an important role in the development of atherosclerosis. However, little is known about the correlation between hydrogen sulfide (H2S), a protective gaseous mediator in atherosclerosis and the process of EndMT.

METHODS

We constructed a stable low-shear-stress-induced(2 dyn/cm2) EndMT model, acombined with the pretreatment method of hydrogen sulfide slow release agent(GYY4137). The level of MEST was detected in the common carotid artery of ApoE-/- mice with local carotid artery ligation. The effect of MEST on atherosclerosis development in vivo was verified using ApoE-/- mice were given tail-vein injection of endothelial-specific overexpressed and knock-down MEST adeno-associated virus (AAV).

RESULTS

These findings confirmed that MEST is up-regulated in low-shear-stress-induced EndMT and atherosclerosis. In vivo experiments showed that MEST gene overexpression significantly promoted EndMT and aggravated the development of atherosclerotic plaques and MEST gene knockdown significantly inhibited EndMT and delayed the process of atherosclerosis. In vitro, H2S inhibits the expression of MEST and EndMT induced by low shear stress and inhibits EndMT induced by MEST overexpression. Knockdown of NFIL3 inhibit the up regulation of MEST and EndMT induced by low shear stress in HUVECs. CHIP-qPCR assay and Luciferase Reporter assay confirmed that NFIL3 binds to MEST DNA, increases its transcription and H2S inhibits the binding of NFIL3 and MEST DNA, weakening NFIL3's transcriptional promotion of MEST. Mechanistically, H2S increased the sulfhydrylation level of NFIL3, an important upstream transcription factors of MEST. In part, transcription factor NFIL3 restrain its binding to MEST DNA by sulfhydration.

CONCLUSIONS

H2S negatively regulate the expression of MEST by sulfhydrylation of NFIL3, thereby inhibiting low-shear-stress-induced EndMT and atherosclerosis.

Strategies for gaseous neuromodulator release in chemical neuroscience: Experimental approaches and translational validation

Gasotransmitters are a group of short-lived gaseous signaling molecules displaying diverse biological functions depending upon their localized concentration. Nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO) are three important examples of endogenously produced gasotransmitters that play a crucial role in human neurophysiology and pathogenesis. Alterations in their optimal physiological concentrations can lead to various severe pathophysiological consequences, including neurological disorders. Exogenous administration of gasotransmitters has emerged as a prominent therapeutic approach for treating such neurological diseases. However, their gaseous nature and short half-life limit their therapeutic delivery. Therefore, developing synthetic gasotransmitter-releasing strategies having control over the release and duration of these gaseous molecules has become imperative. However, the complex chemistry of synthesis and the challenges of specific quantified delivery of these gases, make their therapeutic application a challenging task. This review article provides a focused overview of emerging strategies for delivering gasotransmitters in a controlled and sustained manner to re-establish neurophysiological homeostasis.

Integration of Chemo-mechanical signaling in response to fluid shear stress by the endothelium

Physical forces exert profound effects on cells affecting fate, function, and response to stressors. In the case of the endothelium, the layer that resides in the inner surface of blood vessels, the collective effect of hemodynamic forces influences the onset and severity of vascular pathologies. Justifiably, much emphasis has been placed in understanding how endothelial cells sense and respond to mechanical challenges, particularly hemodynamic shear stress. In this review, we highlight recent developments that have expanded our understanding of the molecular mechanisms underlying mechanotransduction. We describe examples of protein compartmentalization in response to shear stress, consider the contribution of the glycocalyx, and discuss the specific role ion channels in response to flow. We also highlight the recently recognized contribution of the receptor ALK5 in sensing turbulent flow. Research in the last three years has enriched our understanding of the molecular landscape responsible for recognizing and transducing shear stress responses, including novel transcriptional-dependent and transcriptional-independent mechanisms.

Exogenous H2 S promotes ubiquitin-mediated degradation of SREBP1 to alleviate diabetic cardiomyopathy via SYVN1 S-sulfhydration

BACKGROUND

Diabetic cardiomyopathy, a distinctive complication of diabetes mellitus, has been correlated with the presence of intracellular lipid deposits. However, the intricate molecular mechanisms governing the aberrant accumulation of lipid droplets within cardiomyocytes remain to be comprehensively elucidated.

METHODS

Both obese diabetic (db/db) mice and HL-1 cells treated with 200 μmol/L palmitate and 200 μmol/L oleate were used to simulate type 2 diabetes conditions. Transmission electron microscopy is employed to assess the size and quantity of lipid droplets in the mouse hearts. Transcriptomics analysis was utilized to interrogate mRNA levels. Lipidomics and ubiquitinomics were employed to explore the lipid composition alterations and proteins participating in ubiquitin-mediated degradation in mice. Clinical data were collected from patients with diabetes-associated cardiomyopathy and healthy controls. Western blot analysis was conducted to assess the levels of proteins linked to lipid metabolism, and the biotin-switch assay was employed to quantify protein cysteine S-sulfhydration levels.

RESULTS

The administration of H2 S donor, NaHS, effectively restored hydrogen sulfide levels in both the cardiac tissue and plasma of db/db mice (+7%, P < 0.001; +5%, P < 0.001). Both db/db mice (+210%, P < 0.001) and diabetic patients (+83%, P = 0.22, n = 5) exhibit elevated plasma triglyceride levels. Treatment with GYY4137 effectively lowers triglyceride levels in db/db mice (-43%, P = 0.007). The expression of cystathionine gamma-lyase and HMG-CoA reductase degradation protein 1 (SYVN1) was decreased in db/db mice compared with the wild-type mice (cystathionine gamma-lyase: -31%, P = 0.0240; SYVN1: -35%, P = 0.01), and NaHS-treated mice (SYVN1: -31%, P = 0.03). Conversely, the expression of sterol regulatory element-binding protein 1 (SREBP1) was elevated (+91%, P = 0.007; +51%, P = 0.03 compared with control and NaHS-treated mice, respectively), along with diacylglycerol O-acyltransferase 1 (DGAT1) (+95%, P = 0.001; +35%, P = 0.02) and 1-acylglycerol-3-phosphate O-acyltransferase 3 (AGPAT3) (+88%, P = 0.01; +22%, P = 0.32). Exogenous H2 S led to a reduction in lipid droplet formation (-48%, P < 0.001), restoration of SYVN1 expression, modification of SYVN1's S-sulfhydration status and enhancement of SREBP1 ubiquitination. Overexpression of SYVN1 mutated at Cys115 decreased SREBP1 ubiquitination and increased the number of lipid droplets.

CONCLUSIONS

Exogenous H2 S enhances ubiquitin-proteasome degradation of SREBP1 and reduces its nuclear translocation by modulating SYVN1's cysteine S-sulfhydration. This pathway limits lipid droplet buildup in cardiac myocytes, ameliorating diabetic cardiomyopathy.

Sulfur signaling pathway in cardiovascular disease

Hydrogen sulfide (H2S) and sulfur dioxide (SO2), recognized as endogenous sulfur-containing gas signaling molecules, were the third and fourth molecules to be identified subsequent to nitric oxide and carbon monoxide (CO), and exerted diverse biological effects on the cardiovascular system. However, the exact mechanisms underlying the actions of H2S and SO2 have remained elusive until now. Recently, novel post-translational modifications known as S-sulfhydration and S-sulfenylation, induced by H2S and SO2 respectively, have been proposed. These modifications involve the chemical alteration of specific cysteine residues in target proteins through S-sulfhydration and S-sulfenylation, respectively. H2S induced S-sulfhydrylation can have a significant impact on various cellular processes such as cell survival, apoptosis, cell proliferation, metabolism, mitochondrial function, endoplasmic reticulum stress, vasodilation, anti-inflammatory response and oxidative stress in the cardiovascular system. Alternatively, S-sulfenylation caused by SO2 serves primarily to maintain vascular homeostasis. Additional research is warranted to explore the physiological function of proteins with specific cysteine sites, despite the considerable advancements in comprehending the role of H2S-induced S-sulfhydration and SO2-induced S-sulfenylation in the cardiovascular system. The primary objective of this review is to present a comprehensive examination of the function and potential mechanism of S-sulfhydration and S-sulfenylation in the cardiovascular system. Proteins that undergo S-sulfhydration and S-sulfenylation may serve as promising targets for therapeutic intervention and drug development in the cardiovascular system. This could potentially expedite the future development and utilization of drugs related to H2S and SO2.

Protein Persulfidation: Recent Progress and Future Directions

Significance: Hydrogen sulfide (H2S) is considered to be a gasotransmitter along with carbon monoxide (CO) and nitric oxide (NO), and is known as a key regulator of physiological and pathological activities. S-sulfhydration (also known as persulfidation), a mechanism involving the formation of protein persulfides by modification of cysteine residues, is proposed here to explain the multiple biological functions of H2S. Investigating the properties of protein persulfides can provide a foundation for further understanding of the potential functions of H2S. Recent Advances: Multiple methods have been developed to determine the level of protein persulfides. It has been demonstrated that protein persulfidation is involved in many biological processes through various mechanisms including the regulation of ion channels, enzymes, and transcription factors, as well as influencing protein-protein interactions. Critical Issues: Some technical and theoretical questions remain to be solved. These include how to improve the specificity of the detection methods for protein persulfidation, why persulfidation typically occurs on one or a few thiols within a protein, how this modification alters protein functions, and whether protein persulfidation has organ-specific patterns. Future Directions: Optimizing the detection methods and elucidating the properties and molecular functions of protein persulfidation would be beneficial for current therapeutics. In this review, we introduce the detailed mechanism of the persulfidation process and discuss persulfidation detection methods. In addition, this review summarizes recent discoveries of the selectivity of protein persulfidation and the regulation of protein functions and cell signaling pathways by persulfidation. Antioxid. Redox Signal. 39, 829-852.

Skeletal muscle-derived FSTL1 starting up angiogenesis by regulating endothelial junction via activating Src pathway can be upregulated by hydrogen sulfide

Hydrogen sulfide (H2S) promotes microangiogenesis and revascularization after ischemia. Neovascularization starts with the destruction of intercellular junctions and is accompanied by various endothelial cell angiogenic behaviors. Follistatin-like 1 (FSTL1) is a cardiovascular-protective myokine that works against ischemic injury. The present study examined whether FSTL1 was involved in H2S-induced angiogenesis and explored the underlying molecular mechanism. We observed that H2S accelerated blood perfusion after ischemia in the mouse hindlimb ischemia model. Western blot analysis showed that H2S stabilized FSTL1 transcript and increased FSTL1 and Human antigen R (HuR) levels in skeletal muscle. RNA-interference HuR significantly inhibited the H2S-promoted increase in FSTL1 levels. Exogenous FSTL1 promoted the wound-healing migration of human umbilical vein endothelial cells (HUVECs) and increased monolayer endothelial barrier permeability. Immunostaining showed that FSTL1 increased interendothelial gap formation and decreased VE-Cadherin, Occludin, Connexin-43, and Claudin-5 expression. In addition, FSTL1 significantly increased the phosphorylation of Src and VEGFR2. However, the Src inhibitor, not the VEGFR2 inhibitor, could block FSTL1-induced effects in angiogenesis. In conclusion, we demonstrated that H2S could upregulate the expression of FSTL1 by increasing the HuR levels in skeletal muscle, and paracrine FSTL1 could initiate angiogenesis by opening intercellular junctions via the Src signaling pathway.NEW & NOTEWORTHY The myocyte-derived paracrine protein FSTL1 acts on vascular endothelial cells and initiates the process of angiogenesis by opening the intercellular junction via activating Src kinase. H2S can significantly upregulate FSTL1 protein levels in skeletal muscles by increasing HuR expression.

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Disrupted Binding of Cystathionine γ-Lyase to p53 Promotes Endothelial Senescence

BACKGROUND

Advanced age is unequivocally linked to the development of cardiovascular disease; however, the mechanisms resulting in reduced endothelial cell regeneration remain poorly understood. Here, we investigated novel mechanisms involved in endothelial cell senescence that impact endothelial cell transcription and vascular repair after injury.

METHODS

Native endothelial cells were isolated from young (20±3.4 years) and aged (80±2.3 years) individuals and subjected to molecular analyses to assess global transcriptional and metabolic changes. In vitro studies were conducted using primary human and murine endothelial cells. A murine aortic re-endothelialization model was used to examine endothelial cell regenerative capacity in vivo.

RESULTS

RNA sequencing of native endothelial cells revealed that aging resulted in p53-mediated reprogramming to express senescence-associated genes and suppress glycolysis. Reduced glucose uptake and ATP contributed to attenuated assembly of the telomerase complex, which was required for endothelial cell proliferation. Enhanced p53 activity in aging was linked to its acetylation on K120 due to enhanced activity of the acetyltransferase MOZ (monocytic leukemic zinc finger). Mechanistically, p53 acetylation and translocation were, at least partially, attributed to the loss of the vasoprotective enzyme, CSE (cystathionine γ-lyase). CSE physically anchored p53 in the cytosol to prevent its nuclear translocation and CSE absence inhibited AKT (Protein kinase B)-mediated MOZ phosphorylation, which in turn increased MOZ activity and subsequently p53 acetylation. In mice, the endothelial cell-specific deletion of CSE activated p53, induced premature endothelial senescence, and arrested vascular repair after injury. In contrast, the adeno-associated virus 9-mediated re-expression of an active CSE mutant retained p53 in the cytosol, maintained endothelial glucose metabolism and proliferation, and prevented endothelial cell senescence. Adenoviral overexpression of CSE in native endothelial cells from aged individuals maintained low p53 activity and reactivated telomerase to revert endothelial cell senescence.

CONCLUSIONS

Aging-associated impairment of vascular repair is partly determined by the vasoprotective enzyme CSE.

The contribution of the exposome to the burden of cardiovascular disease

Large epidemiological and health impact assessment studies at the global scale, such as the Global Burden of Disease project, indicate that chronic non-communicable diseases, such as atherosclerosis and diabetes mellitus, caused almost two-thirds of the annual global deaths in 2020. By 2030, 77% of all deaths are expected to be caused by non-communicable diseases. Although this increase is mainly due to the ageing of the general population in Western societies, other reasons include the increasing effects of soil, water, air and noise pollution on health, together with the effects of other environmental risk factors such as climate change, unhealthy city designs (including lack of green spaces), unhealthy lifestyle habits and psychosocial stress. The exposome concept was established in 2005 as a new strategy to study the effect of the environment on health. The exposome describes the harmful biochemical and metabolic changes that occur in our body owing to the totality of different environmental exposures throughout the life course, which ultimately lead to adverse health effects and premature deaths. In this Review, we describe the exposome concept with a focus on environmental physical and chemical exposures and their effects on the burden of cardiovascular disease. We discuss selected exposome studies and highlight the relevance of the exposome concept for future health research as well as preventive medicine. We also discuss the challenges and limitations of exposome studies.

Single-Cell RNA-seq Analysis of a Human Embryonic Stem Cell to Endothelial Cell System Based on Transcription Factor Overexpression

BACKGROUND

Human embryonic stem cell (hESC)-derived endothelial cells (ECs) possess therapeutic potential in many diseases. Cytokine supplementation induction and transcription factor overexpression have become two mainstream methods of hESC-EC induction. Single-cell RNA-seq technology has been widely used to analyse dynamic processes during hESC-EC induction and components of induced endothelial cells. However, studies that used single-cell RNA-seq are mainly based on cytokine supplementation methods. In this study, we used a high-efficiency human embryonic stem cell-endothelial cell line (hESC-EC) called the "FLI1-PKC system" as a research model and employed single-cell RNA sequencing (scRNA-seq) to investigate the transcriptional landscape and cellular dynamics.

METHODS

The high-efficiency hESC-EC induction (FLI1-PKC) system was established in our previous study. We applied single-cell RNA sequencing (scRNA-seq) of the differentiated cells at different time points and investigated the gene expression profiles.

RESULTS

The FLI1-PKC induction system can directionally differentiate hESCs into mature endothelial cells with all the requisite functions. Unlike other hES-EC induction protocols, the FLI1-PKC method follows a different induction route; nonetheless, the transcriptome of induced endothelial cells (iECs) remains the same. The elevated number of activated transcription factors may explain why the FLI1-PKC system is more effective than other hES-EC protocols.

CONCLUSION

Our study has presented a single-cell transcriptional overview of a high-efficiency hESC-EC induction system, which can be used as a model and reference for further improvement in other hESC induction systems.

Cystathionine Gamma Lyase Is Regulated by Flow and Controls Smooth Muscle Migration in Human Saphenous Vein

The saphenous vein is the conduit of choice for bypass grafting. Unfortunately, the hemodynamic stress associated with the arterial environment of the bypass vein graft leads to the development of intimal hyperplasia (IH), an excessive cellular growth and collagen deposition that results in restenosis and secondary graft occlusion. Hydrogen sulfide (H2S) is a ubiquitous redox-modifying gasotransmitter that inhibits IH. H2S is produced via the reverse trans-sulfuration pathway by three enzymes: cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). However, the expression and regulation of these enzymes in the human vasculature remains unclear. Here, we investigated the expression of CSE, CBS and 3-MST in segments of native human saphenous vein and large arteries. Furthermore, we evaluated the regulation of these enzymes in vein segments cultured under static, venous (7 mmHg pressure) or arterial (100 mmHg pressure) pressure. CSE was expressed in the media, neointima and intima of the vessels and was negatively regulated by arterial shear stress. Adenoviral-mediated CSE overexpression or RNA interference-mediated CSE knock-down revealed that CSE inhibited primary human VSMC migration but not proliferation. We propose that high shear stress in arteriovenous bypass grafts inhibits CSE expression in both the media and endothelium, which may contribute to increased VSMC migration in the context of IH.

Persulfidation of mitoKv7.4 channels contributes to the cardioprotective effects of the H2S-donor Erucin against ischemia/reperfusion injury

BACKGROUND

Hydrogen sulfide (H2S) is a gasotransmitter deeply involved in cardiovascular homeostasis and implicated in the myocardial protection against ischemia/reperfusion. The post-translational persulfidation of cysteine residues has been identified as the mechanism through which H2S regulates a plethora of biological targets. Erucin (ERU) is an isothiocyanate produced upon hydrolysis of the glucosinolate glucoerucin, presents in edible plants of Brassicaceae family, such as Eruca sativa Mill., and it has emerged as a slow and long-lasting H2S-donor.

AIM

In this study the cardioprotective profile of ERU has been investigated and the action mechanism explored, focusing on the possible role of the recently identified mitochondrial Kv7.4 (mitoKv7.4) potassium channels.

RESULTS

Interestingly, ERU showed to release H2S and concentration-dependently protected H9c2 cells against H2O2-induced oxidative damage. Moreover, in in vivo model of myocardial infarct ERU showed protective effects, reducing the extension of ischemic area, the levels of troponin I and increasing the amount of total AnxA1, as well as co-related inflammatory outcomes. Conversely, the pre-treatment with XE991, a blocker of Kv7.4 channels, abolished them. In isolated cardiac mitochondria ERU exhibited the typical profile of a mitochondrial potassium channels opener, in particular, this isothiocyanate produced a mild depolarization of mitochondrial membrane potential, a reduction of calcium accumulation into the matrix and finally a flow of potassium ions. Finally, mitoKv7.4 channels were persulfidated in ERU-treated mitochondria.

CONCLUSIONS

ERU modulates the cardiac mitoKv7.4 channels and this mechanism may be relevant for cardioprotective effects.

Hydrogen Sulfide-Releasing Indomethacin-Derivative (ATB-344) Prevents the Development of Oxidative Gastric Mucosal Injuries

Hydrogen sulfide (H2S) emerged recently as an anti-oxidative signaling molecule that contributes to gastrointestinal (GI) mucosal defense and repair. Indomethacin belongs to the class of non-steroidal anti-inflammatory drugs (NSAIDs) and is used as an effective intervention in the treatment of gout- or osteoarthritis-related inflammation. However, its clinical use is strongly limited since indomethacin inhibits gastric mucosal prostaglandin (PG) biosynthesis, predisposing to or even inducing ulcerogenesis. The H2S moiety was shown to decrease the GI toxicity of some NSAIDs. However, the GI safety and anti-oxidative effect of a novel H2S-releasing indomethacin derivative (ATB-344) remain unexplored. Thus, we aimed here to compare the impact of ATB-344 and classic indomethacin on gastric mucosal integrity and their ability to counteract the development of oxidative gastric mucosal injuries. Wistar rats were pretreated intragastrically (i.g.) with vehicle, ATB-344 (7-28 mg/kg i.g.), or indomethacin (5-20 mg/kg i.g.). Next, animals were exposed to microsurgical gastric ischemia-reperfusion (I/R). Gastric damage was assessed micro- and macroscopically. The volatile H2S level was assessed in the gastric mucosa using the modified methylene blue method. Serum and gastric mucosal PGE2 and 8-hydroxyguanozine (8-OHG) concentrations were evaluated by ELISA. Molecular alterations for gastric mucosal barrier-specific targets such as cyclooxygenase-1 (COX)-1, COX-2, heme oxygenase-1 (HMOX)-1, HMOX-2, superoxide dismutase-1 (SOD)-1, SOD-2, hypoxia inducible factor (HIF)-1α, xanthine oxidase (XDH), suppressor of cytokine signaling 3 (SOCS3), CCAAT enhancer binding protein (C/EBP), annexin A1 (ANXA1), interleukin 1 beta (IL-1β), interleukin 1 receptor type I (IL-1R1), interleukin 1 receptor type II (IL-1R2), inducible nitric oxide synthase (iNOS), tumor necrosis factor receptor 2 (TNFR2), or H2S-producing enzymes, cystathionine γ-lyase (CTH), cystathionine β-synthase (CBS), or 3-mercaptopyruvate sulfur transferase (MPST), were assessed at the mRNA level by real-time PCR. ATB-344 (7 mg/kg i.g.) reduced the area of gastric I/R injuries in contrast to an equimolar dose of indomethacin. ATB-344 increased gastric H2S production, did not affect gastric mucosal PGE2 content, prevented RNA oxidation, and maintained or enhanced the expression of oxidation-sensitive HMOX-1 and SOD-2 in line with decreased IL-1β and XDH. We conclude that due to the H2S-releasing ability, i.g., treatment with ATB-344 not only exerts dose-dependent GI safety but even enhances gastric mucosal barrier capacity to counteract acute oxidative injury development when applied at a low dose of 7 mg/kg, in contrast to classic indomethacin. ATB-344 (7 mg/kg) inhibited COX activity on a systemic level but did not affect cytoprotective PGE2 content in the gastric mucosa and, as a result, evoked gastroprotection against oxidative damage.

Mapping Pregnancy-dependent Sulfhydrome Unfolds Diverse Functions of Protein Sulfhydration in Human Uterine Artery

Uterine artery (UA) hydrogen sulfide (H2S) production is augmented in pregnancy and, on stimulation by systemic/local vasodilators, contributes to pregnancy-dependent uterine vasodilation; however, how H2S exploits this role is largely unknown. S-sulfhydration converts free thiols to persulfides at reactive cysteine(s) on targeted proteins to affect the entire proteome posttranslationally, representing the main route for H2S to elicit its function. Here, we used Tag-Switch to quantify changes in sulfhydrated (SSH-) proteins (ie, sulfhydrome) in H2S-treated nonpregnant and pregnant human UA. We further used the low-pH quantitative thiol reactivity profiling platform by which paired sulfhydromes were subjected to liquid chromatography tandem mass spectrometry-based peptide sequencing to generate site (cysteine)-specific pregnancy-dependent H2S-responsive human UA sulfhydrome. Total levels of sulfhydrated proteins were significantly greater in pregnant vs nonpregnant human UA and further stimulated by treatment with sodium hydrosulfide. We identified a total of 360 and 1671 SSH-peptides from 480 and 1186 SSH-proteins in untreated and sodium hydrosulfide-treated human UA, respectively. Bioinformatics analyses identified pregnancy-dependent H2S-responsive human UA SSH peptides/proteins, which were categorized to various molecular functions, pathways, and biological processes, especially vascular smooth muscle contraction/relaxation. Pregnancy-dependent changes in these proteins were rectified by immunoblotting of the Tag-Switch labeled SSH proteins. Low-pH quantitative thiol reactivity profiling failed to identify low abundance SSH proteins such as KATP channels in human UA; however, immunoblotting of Tag-Switch-labeled SSH proteins identified pregnancy-dependent upregulation of SSH-KATP channels without altering their total proteins. Thus, comprehensive analyses of human UA sulfhydromes influenced by endogenous and exogenous H2S inform novel roles of protein sulfhydration in uterine hemodynamics regulation.

Effects of Heat Treatment on the Structural and Functional Properties of Phaseolus vulgaris L. Protein

The paper presents the effect of heat treatment at 80 °C at different times (3, 5, 7, and 9 min) on the structural and functional properties of Phaseolus vulgaris L. protein (PVP, bean protein powder). Surface and structure properties of PVP after heat treatment were analyzed using a Fourier transform infrared spectrometer (FTIR), a fluorescence spectrophotometer, a visible light spectrophotometer, a laser particle size analyzer, and other equipment. The secondary structure and surface hydrophobicity (H0) of PVP changed significantly after heat treatment: the β-sheet content decreased from 25.32 ± 0.09% to 24.66 ± 0.09%, the random coil content increased from 23.91 ± 0.11% to 25.68 ± 0.08%, and the H0 rose by 28.96-64.99%. In addition, the functional properties of PVP after heat treatment were analyzed. After heat treatment, the emulsifying activity index (EAI) of PVP increased from 78.52 ± 2.01 m2/g to 98.21 ± 1.33 m2/g, the foaming ability (FA) improved from 87.31 ± 2.56% to 95.82 ± 2.96%, and the foam stability (FS) rose from 53.23 ± 1.72% to 58.71 ± 2.18%. Finally, the degree of hydrolysis (DH) of PVP after gastrointestinal simulated digestion in vitro was detected by the Ortho-Phthal (OPA) method. Heat treatment enhanced the DH of PVP from 62.34 ± 0.31% to 73.64 ± 0.53%. It was confirmed that heat treatment changed the structural properties of PVP and improved its foamability, emulsification, and digestibility. It provides ideas for improving PVP's potential and producing new foods with rich nutrition, multiple functions, and easy absorption.

Plants and Mushrooms as Possible New Sources of H2S Releasing Sulfur Compounds

Hydrogen sulfide (H2S), known for many decades exclusively for its toxicity and the smell of rotten eggs, has been re-discovered for its pleiotropic effects at the cardiovascular and non-cardiovascular level. Therefore, great attention is being paid to the discovery of molecules able to release H2S in a smart manner, i.e., slowly and for a long time, thus ensuring the maintenance of its physiological levels and preventing "H2S-poor" diseases. Despite the development of numerous synthetically derived molecules, the observation that plants containing sulfur compounds share the same pharmacological properties as H2S led to the characterization of naturally derived compounds as H2S donors. In this regard, polysulfuric compounds occurring in plants belonging to the Alliaceae family were the first characterized as H2S donors, followed by isothiocyanates derived from vegetables belonging to the Brassicaceae family, and this led us to consider these plants as nutraceutical tools and their daily consumption has been demonstrated to prevent the onset of several diseases. Interestingly, sulfur compounds are also contained in many fungi. In this review, we speculate about the possibility that they may be novel sources of H2S-donors, furnishing new data on the release of H2S from several selected extracts from fungi.

Emerging Chemical Biology of Protein Persulfidation

Significance: Protein persulfidation (the formation of RSSH), an evolutionarily conserved oxidative posttranslational modification in which thiol groups in cysteine residues are converted into persulfides, has emerged as one of the main mechanisms through which hydrogen sulfide (H2S) conveys its signaling. Recent Advances: New methodological advances in persulfide labeling started unraveling the chemical biology of this modification and its role in (patho)physiology. Some of the key metabolic enzymes are regulated by persulfidation. RSSH levels are important for the cellular defense against oxidative injury, and they decrease with aging, leaving proteins vulnerable to oxidative damage. Persulfidation is dysregulated in many diseases. Critical Issues: A relatively new field of signaling by protein persulfidation still has many unanswered questions: the mechanism(s) of persulfide formation and transpersulfidation and the identification of "protein persulfidases," the improvement of methods to monitor RSSH changes and identify protein targets, and understanding the mechanisms through which this modification controls important (patho)physiological functions. Future Directions: Deep mechanistic studies using more selective and sensitive RSSH labeling techniques will provide high-resolution structural, functional, quantitative, and spatiotemporal information on RSSH dynamics and help with better understanding how H2S-derived protein persulfidation affects protein structure and function in health and disease. This knowledge could pave the way for targeted drug design for a wide variety of pathologies. Antioxid. Redox Signal. 39, 19-39.

Clinical Potential of Hydrogen Sulfide in Peripheral Arterial Disease

Peripheral artery disease (PAD) affects more than 230 million people worldwide. PAD patients suffer from reduced quality of life and are at increased risk of vascular complications and all-cause mortality. Despite its prevalence, impact on quality of life and poor long-term clinical outcomes, PAD remains underdiagnosed and undertreated compared to myocardial infarction and stroke. PAD is due to a combination of macrovascular atherosclerosis and calcification, combined with microvascular rarefaction, leading to chronic peripheral ischemia. Novel therapies are needed to address the increasing incidence of PAD and its difficult long-term pharmacological and surgical management. The cysteine-derived gasotransmitter hydrogen sulfide (H₂S) has interesting vasorelaxant, cytoprotective, antioxidant and anti-inflammatory properties. In this review, we describe the current understanding of PAD pathophysiology and the remarkable benefits of H₂S against atherosclerosis, inflammation, vascular calcification, and other vasculo-protective effects.

The biological functions of protein S-sulfhydration in eukaryotes and the ever-increasing understanding of its effects on bacteria

As a critical endogenous signaling molecule, hydrogen sulfide may induce reversible post-translational modifications on cysteine residues of proteins, generating a persulfide bond known as S-sulfhydration. A systemic overview of the biofunctions of S-sulfhydration will equip us better to characterize its regulatory roles in antioxidant defense, inflammatory response, and cell fate, as well as its pathological mechanisms related to cardiovascular, neurological, and multiple organ diseases, etc. Nevertheless, the understanding of S-sulfhydration is mostly built on mammalian cells and animal models. We subsequently summarized the mediation effects of this specific post-transcriptional modification on physiological processes and virulence in bacteria. The high-sensitivity and high-throughput detection technologies are required for studying the signal transduction mechanism of H₂S and protein S-sulfhydration modification. Herein, we reviewed the establishment and development of different approaches to assess S-sulfhydration, including the biotin-switch method, modified biotin-switch method, alkylation-based cysteine-labelled assay, and Tag-switch method. Finally, we discussed the limitations of the impacts of S-sulfhydration in pathogens-host interactions and envisaged the challenges to design drugs and antibiotics targeting the S-sulfhydrated proteins in the host or pathogens.

Pioglitazone treatment increases the cellular acid-labile and protein-bound sulfane sulfur fractions

BACKGROUND

Iron-sulfur clusters play a central role in cellular function and are regulated by the ATM protein. Iron-sulfur clusters are part of the cellular sulfide pool, which functions to maintain cardiovascular health, and consists of free hydrogen sulfide, iron-sulfur clusters, protein bound sulfides, which constitute the total cellular sulfide fraction. ATM protein signaling and the drug pioglitazone share some cellular effects, which led us to examine the effects of this drug on cellular iron-sulfur cluster formation. Additionally, as ATM functions in the cardiovasculature and its signaling may be diminished in cardiovascular disease, we examined pioglitazone in the same cell type, with and without ATM protein expression.

METHODS

We examined the effects of pioglitazone treatment on the total cellular sulfide profile, the glutathione redox state, cystathionine gamma-lyase enzymatic activity, and on double-stranded DNA break formation in cells with and without ATM protein expression.

RESULTS

Pioglitazone increased the acid-labile (iron-sulfur cluster) and bound sulfur cellular fractions and reduced cystathionine gamma-lyase enzymatic activity in cells with and without ATM protein expression. Interestingly, pioglitazone also increased reduced glutathione and lowered DNA damage in cells without ATM protein expression, but not in ATM wild-type cells. These results are interesting as the acid-labile (iron-sulfur cluster), bound sulfur cellular fractions, and reduced glutathione are low in cardiovascular disease.

CONCLUSION

Here we found that pioglitazone increased the acid-labile (iron-sulfur cluster) and bound sulfur cellular fractions, impinges on hydrogen sulfide synthesis, and exerts beneficial effect on cells with deficient ATM protein signaling. Thus, we show a novel pharmacologic action for pioglitazone.

Endothelial HDAC1-ZEB2-NuRD Complex Drives Aortic Aneurysm and Dissection Through Regulation of Protein S-Sulfhydration

BACKGROUND

Aortic aneurysm and aortic dissection (AAD) are life-threatening vascular diseases, with endothelium being the primary target for AAD treatment. Protein S-sulfhydration is a newly discovered posttranslational modification whose role in AAD has not yet been defined. This study aims to investigate whether protein S-sulfhydration in the endothelium regulates AAD and its underlying mechanism.

METHODS

Protein S-sulfhydration in endothelial cells (ECs) during AAD was detected and hub genes regulating homeostasis of the endothelium were identified. Clinical data of patients with AAD and healthy controls were collected, and the level of the cystathionine γ lyase (CSE)/hydrogen sulfide (H2S) system in plasma and aortic tissue were determined. Mice with EC-specific CSE deletion or overexpression were generated, and the progression of AAD was determined. Unbiased proteomics and coimmunoprecipitation combined with mass spectrometry analysis were conducted to determine the upstream regulators of the CSE/H2S system and the findings were confirmed in transgenic mice.

RESULTS

Higher plasma H2S levels were associated with a lower risk of AAD, after adjustment for common risk factors. CSE was reduced in the endothelium of AAD mouse and aorta of patients with AAD. Protein S-sulfhydration was reduced in the endothelium during AAD and protein disulfide isomerase (PDI) was the main target. S-sulfhydration of PDI at Cys343 and Cys400 enhanced PDI activity and mitigated endoplasmic reticulum stress. EC-specific CSE deletion was exacerbated, and EC-specific overexpression of CSE alleviated the progression of AAD through regulating the S-sulfhydration of PDI. ZEB2 (zinc finger E-box binding homeobox 2) recruited the HDAC1-NuRD complex (histone deacetylase 1-nucleosome remodeling and deacetylase) to repress the transcription of CTH, the gene encoding CSE, and inhibited PDI S-sulfhydration. EC-specific HDAC1 deletion increased PDI S-sulfhydration and alleviated AAD. Increasing PDI S-sulfhydration with the H2S donor GYY4137 or pharmacologically inhibiting HDAC1 activity with entinostat alleviated the progression of AAD.

CONCLUSIONS

Decreased plasma H2S levels are associated with an increased risk of aortic dissection. The endothelial ZEB2-HDAC1-NuRD complex transcriptionally represses CTH, impairs PDI S-sulfhydration, and drives AAD. The regulation of this pathway effectively prevents AAD progression.

The Non-Coding RNA Journal Club: Highlights on Recent Papers-12

We are delighted to share with you our twelfth Journal Club and highlight some of the most interesting papers published recently [...].

Endothelial-dependent S-Sulfhydration of tissue factor pathway inhibitor regulates blood coagulation

Tissue factor pathway inhibitor (TFPI) is an important regulator of coagulation and a link between inflammation and thrombosis. Here we investigated whether endothelial cell-driven oxidative post-translational modifications could have an impact on TFPI activity. We focused on S-sulfhydration, which is a hydrogen sulfide-dependent post-translational modification that, in endothelial cells, is regulated by the enzyme cystathionine γ-lyase (CSE). The study made use of human primary endothelial cells and blood from healthy individuals or subjects with atherosclerosis as well as from mice lacking endothelial CSE. TFPI was S-sulfhydrated in endothelial cells from healthy individuals and mice, while the loss of endothelial CSE expression/activity reduced its modification. Non-S-sulfhydrated TFPI was no longer able to interact with factor Xa, which facilitated the activation of tissue factor. Similarly, non-S-sulfhydratable TFPI mutants bound less protein S, while supplementation with hydrogen sulfide donors, preserved TFPI activity. Phenotypically, loss of TFPI S-sulfhydration increased clot retraction, suggesting that this post-translational modification is a new endothelial cell-dependent mechanism that contributes to the regulation of blood coagulation.

TNF-α-Mediated Endothelial Cell Apoptosis Is Rescued by Hydrogen Sulfide

Endothelial dysfunction is implicated in the development and aggravation of cardiovascular complications. Among the endothelium-released vasoactive factors, hydrogen sulfide (H2S) has been investigated for its beneficial effects on the vasculature through anti-inflammatory and redox-modulating regulatory mechanisms. Reduced H2S bioavailability is reported in chronic diseases such as cardiovascular disease, diabetes, atherosclerosis and preeclampsia, suggesting the value of investigating mechanisms, by which H2S acts as a vasoprotective gasotransmitter. We explored whether the protective effects of H2S were linked to the mitochondrial health of endothelial cells and the mechanisms by which H2S rescues apoptosis. Here, we demonstrate that endothelial dysfunction induced by TNF-α increased endothelial oxidative stress and induced apoptosis via mitochondrial cytochrome c release and caspase activation over 24 h. TNF-α also affected mitochondrial morphology and altered the mitochondrial network. Post-treatment with the slow-releasing H2S donor, GYY4137, alleviated oxidising redox state, decreased pro-caspase 3 activity, and prevented endothelial apoptosis caused by TNF-α alone. In addition, exogenous GYY4137 enhanced S-sulfhydration of pro-caspase 3 and improved mitochondrial health in TNF-α exposed cells. These data provide new insights into molecular mechanisms for cytoprotective effects of H2S via the mitochondrial-driven pathway.

Cell response to mechanical microenvironment cues via Rho signaling: From mechanobiology to mechanomedicine

Mechanical cues in the cell microenvironment such as those from extracellular matrix properties, stretching, compression and shear stress, play a critical role in maintaining homeostasis. Upon sensing mechanical stimuli, cells can translate these external forces into intracellular biochemical signals to regulate their cellular behaviors, but the specific mechanisms of mechanotransduction at the molecular level remain elusive. As a subfamily of the Ras superfamily, Rho GTPases have been recognized as key intracellular mechanotransduction mediators that can regulate multiple cell activities such as proliferation, migration and differentiation as well as biological processes such as cytoskeletal dynamics, metabolism, and organ development. However, the upstream mechanosensors for Rho proteins and downstream effectors that respond to Rho signal activation have not been well illustrated. Moreover, Rho-mediated mechanical signals in previous studies are highly context-dependent. In this review, we systematically summarize the types of mechanical cues in the cell microenvironment and provide recent advances on the roles of the Rho-based mechanotransduction in various cell activities, physiological processes and diseases. Comprehensive insights into the mechanical roles of Rho GTPase partners would open a new paradigm of mechanomedicine for a variety of diseases. STATEMENT OF SIGNIFICANCE: In this review, we highlight the critical role of Rho GTPases as signal mediators to respond to physical cues in microenvironment. This article will add a distinct contribution to this set of knowledge by intensively addressing the relationship between Rho signaling and mechanobiology/mechanotransduction/mechanomedcine. This topic has not been discussed by the journal, nor has it yet been developed by the field. The comprehensive picture that will develop, from molecular mechanisms and engineering methods to disease treatment strategies, represents an important and distinct contribution to the field. We hope that this review would help researchers in various fields, especially clinicians, oncologists and bioengineers, who study Rho signal pathway and mechanobiology/mechanotransduction, understand the critical role of Rho GTPase in mechanotransduction.

Protein persulfidation: Rewiring the hydrogen sulfide signaling in cell stress response

The past few decades have witnessed significant progress in the discovery of hydrogen sulfide (H₂S) as a ubiquitous gaseous signaling molecule in mammalian physiology, akin to nitric oxide and carbon monoxide. As the third gasotransmitter, H₂S is now known to exert a wide range of physiological and cytoprotective functions in the biological systems. However, endogenous H₂S concentrations are usually low, and its potential biologic mechanisms responsible have not yet been fully clarified. Recently, a growing body of evidence has demonstrated that protein persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH) elicited by H₂S, is a fundamental mechanism of H₂S-mediated signaling pathways. Persulfidation, as a biological switch for protein function, plays an important role in the maintenance of cell homeostasis in response to various internal and external stress stimuli and is also implicated in numerous diseases, such as cardiovascular and neurodegenerative diseases and cancer. In this review, the biological significance of protein persulfidation by H₂S in cell stress response is reviewed providing a framework for understanding the multifaceted roles of H₂S. A mechanism-guided perspective can help open novel avenues for the exploitation of therapeutics based on H₂S-induced persulfidation in the context of diseases.

Sulfide regulation of cardiovascular function in health and disease

Hydrogen sulfide (H2S) has emerged as a gaseous signalling molecule with crucial implications for cardiovascular health. H2S is involved in many biological functions, including interactions with nitric oxide, activation of molecular signalling cascades, post-translational modifications and redox regulation. Various preclinical and clinical studies have shown that H2S and its synthesizing enzymes - cystathionine γ-lyase, cystathionine β-synthase and 3-mercaptosulfotransferase - can protect against cardiovascular pathologies, including arrhythmias, atherosclerosis, heart failure, myocardial infarction and ischaemia-reperfusion injury. The bioavailability of H2S and its metabolites, such as hydropersulfides and polysulfides, is substantially reduced in cardiovascular disease and has been associated with single-nucleotide polymorphisms in H2S synthesis enzymes. In this Review, we highlight the role of H2S, its synthesizing enzymes and metabolites, their roles in the cardiovascular system, and their involvement in cardiovascular disease and associated pathologies. We also discuss the latest clinical findings from the field and outline areas for future study.

The endothelial-enriched lncRNA LINC00607 mediates angiogenic function

Long non-coding RNAs (lncRNAs) can act as regulatory RNAs which, by altering the expression of target genes, impact on the cellular phenotype and cardiovascular disease development. Endothelial lncRNAs and their vascular functions are largely undefined. Deep RNA-Seq and FANTOM5 CAGE analysis revealed the lncRNA LINC00607 to be highly enriched in human endothelial cells. LINC00607 was induced in response to hypoxia, arteriosclerosis regression in non-human primates, post-atherosclerotic cultured endothelial cells from patients and also in response to propranolol used to induce regression of human arteriovenous malformations. siRNA knockdown or CRISPR/Cas9 knockout of LINC00607 attenuated VEGF-A-induced angiogenic sprouting. LINC00607 knockout in endothelial cells also integrated less into newly formed vascular networks in an in vivo assay in SCID mice. Overexpression of LINC00607 in CRISPR knockout cells restored normal endothelial function. RNA- and ATAC-Seq after LINC00607 knockout revealed changes in the transcription of endothelial gene sets linked to the endothelial phenotype and in chromatin accessibility around ERG-binding sites. Mechanistically, LINC00607 interacted with the SWI/SNF chromatin remodeling protein BRG1. CRISPR/Cas9-mediated knockout of BRG1 in HUVEC followed by CUT&RUN revealed that BRG1 is required to secure a stable chromatin state, mainly on ERG-binding sites. In conclusion, LINC00607 is an endothelial-enriched lncRNA that maintains ERG target gene transcription by interacting with the chromatin remodeler BRG1 to ultimately mediate angiogenesis.

Hydrogen Sulfide Modulates Endothelial-Mesenchymal Transition in Heart Failure

BACKGROUND

Hydrogen sulfide is a critical endogenous signaling molecule that exerts protective effects in the setting of heart failure. Cystathionine γ-lyase (CSE), 1 of 3 hydrogen-sulfide-producing enzyme, is predominantly localized in the vascular endothelium. The interaction between the endothelial CSE-hydrogen sulfide axis and endothelial-mesenchymal transition, an important pathological process contributing to the formation of fibrosis, has yet to be investigated.

METHODS

Endothelial-cell-specific CSE knockout and Endothelial cell-CSE overexpressing mice were subjected to transverse aortic constriction to induce heart failure with reduced ejection fraction. Cardiac function, vascular reactivity, and treadmill exercise capacity were measured to determine the severity of heart failure. Histological and gene expression analyses were performed to investigate changes in cardiac fibrosis and the activation of endothelial-mesenchymal transition.

RESULTS

Endothelial-cell-specific CSE knockout mice exhibited increased endothelial-mesenchymal transition and reduced nitric oxide bioavailability in the myocardium, which was associated with increased cardiac fibrosis, impaired cardiac and vascular function, and worsened exercise performance. In contrast, genetic overexpression of CSE in endothelial cells led to increased myocardial nitric oxide, decreased endothelial-mesenchymal transition and cardiac fibrosis, preserved cardiac and endothelial function, and improved exercise capacity.

CONCLUSIONS

Our data demonstrate that endothelial CSE modulates endothelial-mesenchymal transition and ameliorate the severity of pressure-overload-induced heart failure, in part, through nitric oxide-related mechanisms. These data further suggest that endothelium-derived hydrogen sulfide is a potential therapeutic for the treatment of heart failure with reduced ejection fraction.

Targeting hydrogen sulfide and nitric oxide to repair cardiovascular injury after trauma

The systemic cardiovascular effects of major trauma, especially neurotrauma, contribute to death and permanent disability in trauma patients and treatments are needed to improve outcomes. In some trauma patients, dysfunction of the autonomic nervous system produces a state of adrenergic overstimulation, causing either a sustained elevation in catecholamines (sympathetic storm) or oscillating bursts of paroxysmal sympathetic hyperactivity. Trauma can also activate innate immune responses that release cytokines and damage-associated molecular patterns into the circulation. This combination of altered autonomic nervous system function and widespread systemic inflammation produces secondary cardiovascular injury, including hypertension, damage to cardiac tissue, vascular endothelial dysfunction, coagulopathy and multiorgan failure. The gasotransmitters nitric oxide (NO) and hydrogen sulfide (H2S) are small gaseous molecules with potent effects on vascular tone regulation. Exogenous NO (inhaled) has potential therapeutic benefit in cardio-cerebrovascular diseases, but limited data suggests potential efficacy in traumatic brain injury (TBI). H2S is a modulator of NO signaling and autonomic nervous system function that has also been used as a drug for cardio-cerebrovascular diseases. The inhaled gases NO and H2S are potential treatments to restore cardio-cerebrovascular function in the post-trauma period.

Detection of sulfane sulfur species in biological systems

Sulfane sulfur species such as hydropersulfides (RSSH), polysulfides (RSnR), and hydrogen polysulfides (H2Sn) are critically involved in sulfur-mediated redox signaling, but their detailed mechanisms of action need further clarification. Therefore, there is a need to develop selective and sensitive sulfane sulfur detection methods to gauge a better understanding of their functions. This review summarizes current detection methods that include cyanolysis, chemical derivatization and mass spectrometry, proteomic analysis, fluorescent probes, and resonance synchronous/Raman spectroscopic methods. The design principles, advantages, applications, and limitations of each method are discussed, along with suggested directions for future research on these methods. The development of robust detection methods for sulfane sulfur species will help to elucidate their mechanisms and functions in biological systems.

Cystathionine γ lyase S-sulfhydrates Drp1 to ameliorate heart dysfunction

Hydrogen sulfide (H₂S), produced by cystathionine γ lyase (CSE), is an important endogenous gasotransmitter to maintain heart function. However, the molecular mechanism for how H₂S influences the mitochondrial morphology during heart failure remains poorly understood. Here, we found that CSE/H₂S pathway mediated cardiac function and mitochondrial morphology through regulating dynamin related protein 1 (Drp1) activity and translocation. Mechanistically, elevation of H₂S levels by CSE overexpression declined protein level, phosphorylation (Ser 616), oligomerization and GTPase activity of Drp1 by S-sulfhydration in mouse hearts. Interestingly, Drp1 S-sulfhydration directly competed with S-nitrosylation by nitric oxide at the specific cysteine 607. The non-S-sulfhydration of Drp1 mutation (C607A) attenuated the regulatory effect of H₂S on Drp1 activation, mitochondrial fission and heart function. Moreover, the non-canonical role of Drp1 mediated isoprenaline-induced mitochondrial dysfunction and cardiomyocyte death through interaction with voltage-dependent anion channel 1. These results uncover that a novel mechanism that H₂S S-sulfhydrated Drp1 at cysteine 607 to prevent heart failure through modulating its activity and mitochondrial translocation. Our findings also provide initial evidence demonstrating that Drp1 may be a critical regulator as well as an effective strategy for heart dysfunction.

Unravelling the impact of aging on the human endothelial lncRNA transcriptome

The incidence and prevalence of cardiovascular disease is highest among the elderly. There is a need to further understand the mechanisms behind endothelial cell aging in order to achieve vascular rejuvenation and minimize the onset of age-related vascular diseases. Long non-coding RNAs (lncRNAs) have been proposed to regulate numerous processes in the human genome, yet their function in vascular aging and their therapeutic potential remain largely unknown. This is primarily because the majority of studies investigating the impact of aging on lncRNA expression heavily rely on in vitro studies based on replicative senescence. Here, using a unique collection of young and aged endothelial cells isolated from native human arteries, we sought to characterize the age-related alterations in lncRNA expression profiles. We were able to detect a total of 4463 lncRNAs expressed in the human endothelium from which ∼17% (798) were altered in advanced age. One of the most affected lncRNAs in aging was the primate-specific, Prostate Cancer Associated Transcript (PCAT) 14. In our follow up analysis, using single molecule RNA FISH, we showed that PCAT14 is relatively abundant, localized almost exclusively in the nucleus of young endothelial cells, and silenced in the aged endothelium. Functionally, our studies proposed that downregulation of PCAT14 alters endothelial cell transcription profile and cell functions including endothelial cell migration, sprouting and inflammatory responses in vitro. Taken together, our data highlight that endothelial cell aging correlates with altered expression of lncRNAs, which could impair the endothelial regenerative capacity and enhance inflammatory phenotypes.

A coalition to heal-the impact of the cardiac microenvironment

Heart regenerative medicine has been gradually evolving from a view of the heart as a nonregenerative organ with terminally differentiated cardiac muscle cells. Understanding the biology of the heart during homeostasis and in response to injuries has led to the realization that cellular communication between all cardiac cell types holds great promise for treatments. Indeed, recent studies highlight new disease-reversion concepts in addition to cardiomyocyte renewal, such as matrix- and vascular-targeted therapies, and immunotherapy with a focus on inflammation and fibrosis. In this review, we will discuss the cross-talk within the cardiac microenvironment and how specific therapies aim to target the hostile cardiac milieu under pathological conditions.

Functional Regulation of KATP Channels and Mutant Insight Into Clinical Therapeutic Strategies in Cardiovascular Diseases

ATP-sensitive potassium channels (K_ATP channels) play pivotal roles in excitable cells and link cellular metabolism with membrane excitability. The action potential converts electricity into dynamics by ion channel-mediated ion exchange to generate systole, involved in every heartbeat. Activation of the K_ATP channel repolarizes the membrane potential and decreases early afterdepolarization (EAD)-mediated arrhythmias. K_ATP channels in cardiomyocytes have less function under physiological conditions but they open during severe and prolonged anoxia due to a reduced ATP/ADP ratio, lessening cellular excitability and thus preventing action potential generation and cell contraction. Small active molecules activate and enhance the opening of the K_ATP channel, which induces the repolarization of the membrane and decreases the occurrence of malignant arrhythmia. Accumulated evidence indicates that mutation of K_ATP channels deteriorates the regulatory roles in mutation-related diseases. However, patients with mutations in K_ATP channels still have no efficient treatment. Hence, in this study, we describe the role of K_ATP channels and subunits in angiocardiopathy, summarize the mutations of the K_ATP channels and the functional regulation of small active molecules in K_ATP channels, elucidate the potential mechanisms of mutant K_ATP channels and provide insight into clinical therapeutic strategies.

Inhibition of the 3-mercaptopyruvate sulfurtransferase-hydrogen sulfide system promotes cellular lipid accumulation

H₂S is generated in the adipose tissue by cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase (3-MST). H₂S plays multiple roles in the regulation of various metabolic processes, including insulin resistance. H₂S biosynthesis also occurs in adipocytes. Aging is known to be associated with a decline in H₂S. Therefore, the question arises whether endogenous H₂S deficiency may affect the process of adipocyte maturation and lipid accumulation. Among the three H₂S-generating enzymes, the role of 3-MST is the least understood in adipocytes. Here we tested the effect of the 3-MST inhibitor 2-[(4-hydroxy-6-methylpyrimidin-2-yl)sulfanyl]-1-(naphthalen-1-yl)ethan-1-one (HMPSNE) and the H₂S donor (GYY4137) on the differentiation and adipogenesis of the adipocyte-like cells 3T3-L1 in vitro. 3T3-L1 cells were differentiated into mature adipocytes in the presence of GYY4137 or HMPSNE. HMPSNE significantly enhanced lipid accumulation into the maturing adipocytes. On the other hand, suppressed lipid accumulation was observed in cells treated with the H₂S donor. 3-MST inhibition increased, while H₂S donation suppressed the expression of various H₂S-producing enzymes during adipocyte differentiation. 3-MST knockdown also facilitated adipocytic differentiation and lipid uptake. The underlying mechanisms may involve impairment of oxidative phosphorylation and fatty acid oxidation as well as the activation of various differentiation-associated transcription factors. Thus, the 3-MST/H₂S system plays a tonic role in suppressing lipid accumulation and limiting the differentiation of adipocytes. Stimulation of 3-MST activity or supplementation of H₂S—which has been recently linked to various experimental therapeutic approaches during aging—may be a potential experimental approach to counteract adipogenesis.

Emerging roles of cystathionine β-synthase in various forms of cancer

The expression of the reverse transsulfuration enzyme cystathionine-β-synthase (CBS) is markedly increased in many forms of cancer, including colorectal, ovarian, lung, breast and kidney, while in other cancers (liver cancer and glioma) it becomes downregulated. According to the clinical database data in high-CBS-expressor cancers (e.g. colon or ovarian cancer), high CBS expression typically predicts lower survival, while in the low-CBS-expressor cancers (e.g. liver cancer), low CBS expression is associated with lower survival. In the high-CBS expressing tumor cells, CBS, and its product hydrogen sulfide (H₂S) serves as a bioenergetic, proliferative, cytoprotective and stemness factor; it also supports angiogenesis and epithelial-to-mesenchymal transition in the cancer microenvironment. The current article reviews the various tumor-cell-supporting roles of the CBS/H₂S axis in high-CBS expressor cancers and overviews the anticancer effects of CBS silencing and pharmacological CBS inhibition in various cancer models in vitro and in vivo; it also outlines potential approaches for biomarker identification, to support future targeted cancer therapies based on pharmacological CBS inhibition.

Physiological roles of hydrogen sulfide in mammalian cells, tissues and organs

H2S belongs to the class of molecules known as gasotransmitters, which also includes nitric oxide (NO) and carbon monoxide (CO). Three enzymes are recognized as endogenous sources of H2S in various cells and tissues: cystathionine g-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current article reviews the regulation of these enzymes as well as the pathways of their enzymatic and non-enzymatic degradation and elimination. The multiple interactions of H2S with other labile endogenous molecules (e.g. NO) and reactive oxygen species are also outlined. The various biological targets and signaling pathways are discussed, with special reference to H2S and oxidative posttranscriptional modification of proteins, the effect of H2S on channels and intracellular second messenger pathways, the regulation of gene transcription and translation and the regulation of cellular bioenergetics and metabolism. The pharmacological and molecular tools currently available to study H2S physiology are also reviewed, including their utility and limitations. In subsequent sections, the role of H2S in the regulation of various physiological and cellular functions is reviewed. The physiological role of H2S in various cell types and organ systems are overviewed. Finally, the role of H2S in the regulation of various organ functions is discussed as well as the characteristic bell-shaped biphasic effects of H2S. In addition, key pathophysiological aspects, debated areas, and future research and translational areas are identified A wide array of significant roles of H2S in the physiological regulation of all organ functions emerges from this review.

Potential Effects of Natural H2S-Donors in Hypertension Management

After the discovery of hydrogen sulfide (H₂S) in the central nervous system by Abe and Kimura in 1996, the physiopathological role of H₂S has been widely investigated in several systems such as the cardiovascular. In particular, H₂S plays a pivotal role in the control of vascular tone, exhibiting mechanisms of action able to induce vasodilation: for instance, activation of potassium channels (KATP and Kv7) and inhibition of 5-phosphodiesterase (5-PDE). These findings paved the way for the research of natural and synthetic exogenous H₂S-donors (i.e., molecules able to release H₂S) in order to have new tools for the management of hypertension. In this scenario, some natural molecules derived from Alliaceae (i.e., garlic) and Brassicaceae (i.e., rocket or broccoli) botanical families show the profile of slow H₂S-donors able to mimic the endogenous production of this gasotransmitter and therefore can be viewed as interesting potential tools for management of hypertension or pre-hypertension. In this article, the preclinical and clinical impacts of these natural H₂S-donors on hypertension and vascular integrity have been reviewed in order to give a complete panorama of their potential use for the management of hypertension and related vascular diseases.