Hydrogen sulfide blocks HIV rebound by maintaining mitochondrial bioenergetics and redox homeostasis

Sulfide regulation and catabolism in health and disease

The metabolic pathway of sulfur-containing amino acids in organisms begins with methionine, which is metabolized to produce important sulfur-containing biomolecules such as adenosylmethionine, adenosylhomocysteine, homocysteine, cystine, and hydrogen sulfide (H2S). These sulfur-containing biomolecules play a wide range of physiological roles in the body, including anti-inflammation, antioxidant stress, DNA methylation, protein synthesis, etc., which are essential for maintaining cellular function and overall health. In contrast, dysregulation of the metabolic pathway of sulfur-containing amino acids leads to abnormal levels of sulfur-containing biomolecules, which produce a range of pathological consequences in multiple systems of the body, such as neurodegenerative diseases, cardiovascular diseases, and cancer. This review traces the milestones in the development of these sulfur-containing biomolecules from their initial discovery to their clinical applications and describes in detail the structure, physiochemical properties, metabolism, sulfide signaling pathway, physiopathological functions, and assays of sulfur-containing biomolecules. In addition, the paper also explores the regulatory role and mechanism of sulfur-containing biomolecules on cardiovascular diseases, liver diseases, neurological diseases, metabolic diseases and tumors. The focus is placed on donors of sulfur-containing biological macromolecule metabolites, small-molecule drug screening targeting H2S-producing enzymes, and the latest advancements in preclinical and clinical research related to hydrogen sulfide, including clinical trials and FDA-approved drugs. Additionally, an overview of future research directions in this field is provided. The aim is to enhance the understanding of the complex physiological and pathological roles of sulfur-containing biomolecules and to offer insights into developing effective therapeutic strategies for diseases associated with dysregulated sulfur-containing amino acid metabolism.

Ag/Cu2O nanoarray sensors for rapid detection of Bio-H2S in human blood

The concentration of hydrogen sulfide (H2S) in human blood is closely associated with various chronic diseases. Therefore, it is imperative to design a sensor that can conveniently, rapidly, and accurately detect H2S in human blood at room temperature. In this work, we developed an Ag/Cu2O-based sensor using a two-dimensional electrodeposition in situ assembly method for detecting biological hydrogen sulfide (bio-H2S). The morphological and structural properties indicate that a distinct contact interface has been established between Ag and Cu2O. The sensor exhibits high selectivity, good stability, and a strong linear response within the range of 50-250 μM (R2 = 0.999 58). At room temperature, the sensor displayed a remarkable response of up to 12 704.35% when exposed to 250 μM bio-H2S in blood, with a response time of just 40 s. The great sensing ability of Ag/Cu2O nanoarray for bio-H2S detection is mainly attributed to Schottky barrier modulation of Ag/Cu2O, catalytic sensitization of Ag nanowires, and vulcanization reaction of Cu2O. These results provide significant perspectives for the early diagnosis of chronic diseases and the real-time monitoring of blood-related diseases.

Orthogonal Persulfide Generation through Precision Tools Provides Insights into Mitochondrial Sulfane Sulfur

The sulfane sulfur pool, comprised of persulfide (RS-SH) and polysulfide (RS-SnH) derived from hydrogen sulfide (H2S), has emerged as a major player in redox biochemistry. Mitochondria, besides energy generation, serve as significant cellular redox hubs, mediate stress response and cellular health. However, the effects of endogenous mitochondrial sulfane sulfur (MSS) remain largely uncharacterized as compared with their cytosolic counterparts, cytosolic sulfane sulfur (CSS). To investigate this, we designed a novel artificial substrate for mitochondrial 3-mercaptopyruvate sulfurtransferase (3-MST), a key enzyme involved in MSS biosynthesis. Using cells expressing a mitochondrion-localized persulfide biosensor, we demonstrate this tool's ability to selectively enhance MSS. While H2S was previously known to suppress human immunodeficiency virus (HIV-1), we found that MSS profoundly affected the HIV-1 life cycle, mediating viral reactivation from latency. Additionally, we provide evidence for the role of the host's mitochondrial redox state, membrane potential, apoptosis, and respiration rates in managing HIV-1 latency and reactivation. Together, dynamic fluctuations in the MSS pool have a significant and possibly conflicting effect on HIV-1 viral latency. The precision tools developed herein allow for orthogonal generation of persulfide within both mitochondria and the cytosol and will be useful in interrogating disease biology.

GLUT1 overexpression in CAR-T cells induces metabolic reprogramming and enhances potency

The intensive nutrient requirements needed to sustain T cell activation and proliferation, combined with competition for nutrients within the tumor microenvironment, raise the prospect that glucose availability may limit CAR-T cell function. Here, we seek to test the hypothesis that stable overexpression (OE) of the glucose transporter GLUT1 in primary human CAR-T cells would improve their function and antitumor potency. We observe that GLUT1OE in CAR-T cells increases glucose consumption, glycolysis, glycolytic reserve, and oxidative phosphorylation, and these effects are associated with decreased T cell exhaustion and increased Th17 differentiation. GLUT1OE also induces broad metabolic reprogramming associated with increased glutathione-mediated resistance to reactive oxygen species, and increased inosine accumulation. When challenged with tumors, GLUT1OE CAR-T cells secrete more proinflammatory cytokines and show enhanced cytotoxicity in vitro, and demonstrate superior tumor control and persistence in mouse models. Our collective findings support a paradigm wherein glucose availability is rate limiting for effector CAR-T cell function and demonstrate that enhancing glucose availability via GLUT1OE could augment antitumor immune function.

Hydrogen sulfide maintains mitochondrial homeostasis and regulates ganoderic acids biosynthesis by SQR under heat stress in Ganoderma lucidum

Hydrogen sulfide (H2S) has recently been recognized as an important gaseous transmitter with multiple physiological effects in various species. Previous studies have shown that H2S alleviated heat-induced ganoderic acids (GAs) biosynthesis, an important quality index of Ganoderma lucidum. However, a comprehensive understanding of the physiological effects and molecular mechanisms of H2S in G. lucidum remains unexplored. In this study, we found that heat treatment reduced the mitochondrial membrane potential (MMP) and mitochondrial DNA copy number (mtDNAcn) in G. lucidum. Increasing the intracellular H2S concentration through pharmacological and genetic means increased the MMP level, mtDNAcn, oxygen consumption rate level and ATP content under heat treatment, suggesting a role for H2S in mitigating heat-caused mitochondrial damage in G. lucidum. Further results indicated that H2S activates sulfide-quinone oxidoreductase (SQR) and complex III (Com III), thereby maintaining mitochondrial homeostasis under heat stress in G. lucidum. Moreover, SQR also mediated the negative regulation of H2S to GAs biosynthesis under heat stress. Furthermore, SQR might be persulfidated under heat stress in G. lucidum. Thus, our study reveals a novel physiological function and molecular mechanism of H2S signalling under heat stress in G. lucidum with broad implications for research on the environmental response of microorganisms.

GYY4137-Derived Hydrogen Sulfide Donates Electrons to the Mitochondrial Electron Transport Chain via Sulfide: Quinone Oxidoreductase in Endothelial Cells

The protective effects of hydrogen sulphide (H2S) to limit oxidative injury and preserve mitochondrial function during sepsis, ischemia/reperfusion, and neurodegenerative diseases have prompted the development of soluble H2S-releasing compounds such as GYY4137. Yet, the effects of GYY4137 on the mitochondrial function of endothelial cells remain unclear, while this cell type comprises the first target cell after parenteral administration. Here, we specifically assessed whether human endothelial cells possess a functional sulfide:quinone oxidoreductase (SQOR), to oxidise GYY4137-released H2S within the mitochondria for electron donation to the electron transport chain. We demonstrate that H2S administration increases oxygen consumption by human umbilical vein endothelial cells (HUVECs), which does not occur in the SQOR-deficient cell line SH-SY5Y. GYY4137 releases H2S in HUVECs in a dose- and time-dependent fashion as quantified by oxygen consumption and confirmed by lead acetate assay, as well as AzMC fluorescence. Scavenging of intracellular H2S using zinc confirmed intracellular and intramitochondrial sulfur, which resulted in mitotoxic zinc sulfide (ZnS) precipitates. Together, GYY4137 increases intramitochondrial H2S and boosts oxygen consumption of endothelial cells, which is likely governed via the oxidation of H2S by SQOR. This mechanism in endothelial cells may be instrumental in regulating H2S levels in blood and organs but can also be exploited to quantify H2S release by soluble donors such as GYY4137 in living systems.

Hydrogen Sulfide Donor GYY4137 Rescues NRF2 Activation in Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) can cause severe respiratory illness in infants, immunocompromised, and older adults. Despite its burden, no vaccine or specific treatment is available. RSV infection is associated with increased reactive oxygen species (ROS) production, degradation of the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2), and decreased antioxidant enzymes (AOEs), leading to oxidative damage and lung injury. Hydrogen sulfide (H2S) is an endogenous gaseous molecule that plays a physiological role in numerous cellular processes and a protective role in multiple pathological conditions, displaying vasoactive, cytoprotective, anti-inflammatory, and antioxidant activities. H2S can promote NRF2 activation through the sulfhydration of Kelch-like ECH-associated protein 1, the cytoplasmic repressor of NRF2. Here we investigated whether increasing cellular H2S levels could rescue NRF2 and NRF2-dependent gene expression in RSV-infected primary airway epithelial cells. We found that treatment with the H2S donor GYY4137 significantly increased NRF2 levels and AOEs gene expression by decreasing KEAP1 levels, and by modulating pathways involved in RSV-induced NRF2 degradation, such as NRF2 ubiquitination, and promyelocytic leukemia (PML) protein levels. These results suggest that the administration of exogenous H2S can positively impact the altered redox balance associated with RSV infection, which represents an important determinant of RSV-induced lung disease.

Anomalous HIV-1 RNA, How Cap-Methylation Segregates Viral Transcripts by Form and Function

The acquisition of m7G-cap-binding proteins is now recognized as a major variable driving the form and function of host RNAs. This manuscript compares the 5'-cap-RNA binding proteins that engage HIV-1 precursor RNAs, host mRNAs, small nuclear (sn)- and small nucleolar (sno) RNAs and sort into disparate RNA-fate pathways. Before completion of the transcription cycle, the transcription start site of nascent class II RNAs is appended to a non-templated guanosine that is methylated (m7G-cap) and bound by hetero-dimeric CBP80-CBP20 cap binding complex (CBC). The CBC is a nexus for the co-transcriptional processing of precursor RNAs to mRNAs and the snRNA and snoRNA of spliceosomal and ribosomal ribonucleoproteins (RNPs). Just as sn/sno-RNAs experience hyper-methylation of m7G-cap to trimethylguanosine (TMG)-cap, so do select HIV RNAs and an emerging cohort of mRNAs. TMG-cap is blocked from Watson:Crick base pairing and disqualified from participating in secondary structure. The HIV TMG-cap has been shown to license select viral transcripts for specialized cap-dependent translation initiation without eIF4E that is dependent upon CBP80/NCBP3. The exceptional activity of HIV precursor RNAs secures their access to maturation pathways of sn/snoRNAs, canonical and non-canonical host mRNAs in proper stoichiometry to execute the retroviral replication cycle.