Effect of Modified Forms of Sodium Humate PowHumus on the Balance of Arginine in Peritoneal Macrophages of Intact Mice.

Substances of silver nanoparticles dialyzed through a 13 kDa membrane, synthesized in a medium of humic ligands modified with hydroquinone and 2-hydroxynaphthoquinone from PowHumus brown coal, specifically enhance the M2 properties of peritoneal macrophages due to inhibition of NO synthase and significant activation of arginase, thus enhancing anti-inflammatory properties of cells. In small, but effective concentrations, they do not have cytotoxic properties and do not contain pyrogenic impurities. The studied humates are able to influence the mechanisms of immune response formation and are an effective means for correcting inflammation and regeneration.

Inonotus obliquus (Chaga) against HFD/STZ-induced glucolipid metabolism disorders and abnormal renal functions by regulating NOS-cGMP-PDE5 signaling pathway.

Our prior investigations have established that Inonotus obliquus (Chaga) possesses hypoglycemic effects. Persistent hyperglycemia is known to precipitate renal function abnormalities. The functionality of the kidneys is intricately linked to the levels of cyclic guanosine-3',5'-monophosphate (cGMP), which are influenced by the activities of nitric oxide synthase (NOS) and phosphodiesterase (PDE). Enhanced cGMP levels can be achieved either through the upregulation of NOS activity or the downregulation of PDE activity. The objective of the current study is to elucidate the effects of Chaga on disorders of glucolipid metabolism and renal abnormalities in rats with type 2 diabetes mellitus (T2DM), while concurrently examining the NOS-cGMP-PDE5 signaling pathway. A model of T2DM was developed in rats using a high-fat diet (HFD) combined with streptozotocin (STZ) administration, followed by treatment with Chaga extracts at doses of 50 and 100 mg·kg-1 for eight weeks. The findings revealed that Chaga not only mitigated metabolic dysfunctions, evidenced by improvements in fasting blood glucose, total cholesterol, triglycerides, and insulin resistance, but also ameliorated renal function markers, including serum creatinine, urine creatinine (UCr), blood urea nitrogen, 24-h urinary protein, and estimated creatinine clearance. Additionally, enhancements in glomerular volume, GBM thickness, podocyte foot process width (FPW), and the mRNA and protein expressions of podocyte markers, such as nephrin and wilms tumor-1, were observed. Chaga was found to elevate cGMP levels in both serum and kidney tissues by increasing mRNA and protein expressions of renal endothelial NOS and neural NOS, while simultaneously reducing the expressions of renal inducible NOS and PDE5. In summary, Chaga counteracts HFD/STZ-induced glucolipid metabolism and renal function disturbances by modulating the NOS-cGMP-PDE5 signaling pathway. This research supports the potential application of Chaga in the clinical prevention and treatment of T2DM and diabetic nephropathy (DN), with cGMP serving as a potential therapeutic target.

Cortical nitric oxide required for presynaptic long-term potentiation in the insular cortex.

Nitric oxide (NO) is a key diffusible messenger in the mammalian brain. It has been proposed that NO may diffuse retrogradely into presynaptic terminals, contributing to the induction of hippocampal long-term potentiation (LTP). Here, we present novel evidence that NO is required for kainate receptor (KAR)-dependent presynaptic form of LTP (pre-LTP) in the adult insular cortex (IC). In the IC, we found that inhibition of NO synthase erased the maintenance of pre-LTP, while the induction of pre-LTP required the activation of KAR. Furthermore, NO is essential for pre-LTP induced between two pyramidal cells in the IC using the double patch-clamp recording. These results suggest that NO is required for homosynaptic pre-LTP in the IC. Our results present strong evidence for the critical roles of NO in pre-LTP in the IC. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

New advances in the protective mechanisms of acidic pH after ischemia: Participation of NO.

BACKGROUND: It has been previously demonstrated that the maintenance of ischemic acidic pH or the delay of intracellular pH recovery at the onset of reperfusion decreases ischemic-induced cardiomyocyte death. OBJECTIVE: To examine the role played by nitric oxide synthase (NOS)/NO-dependent pathways in the effects of acidic reperfusion in a regional ischemia model. METHODS: Isolated rat hearts perfused by Langendorff technique were submitted to 40 min of left coronary artery occlusion followed by 60 min of reperfusion (IC). A group of hearts received an acid solution (pH = 6.4) during the first 2 min of reperfusion (AR) in absence or in presence of l-NAME (NOS inhibitor). Infarct size (IS) and myocardial function were determined. In cardiac homogenates, the expression of P-Akt, P-endothelial and inducible isoforms of NOS (P-eNOS and iNOS) and the level of 3-nitrotyrosine were measured. In isolated cardiomyocytes, the intracellular NO production was assessed by confocal microscopy, under control and acidic conditions. Mitochondrial swelling after Ca2+ addition and mitochondrial membrane potential (Δψ) were also determined under control and acidosis. RESULTS: AR decreased IS, improved postischemic myocardial function recovery, increased P-Akt and P-eNOS, and decreased iNOS and 3-nitrotyrosine. NO production increased while mitochondrial swelling and Δψ decreased in acidic conditions. l-NAME prevented the beneficial effects of AR. CONCLUSIONS: Our data strongly supports that a brief acidic reperfusion protects the myocardium against the ischemia-reperfusion injury through eNOS/NO-dependent pathways.

Enhancement of colour formation of fermented sausages by overexpression of nitric oxide synthase in Staphylococcus vitulinus under hydrogen peroxide stress.

This study used hydrogen peroxide (H2O2) treatment to overexpress the gene of nitric oxide synthase (nos) in Staphylococcus vitulinus, which was then inoculated into fermented sausages to observe its effect on colour development. The results showed that a low concentration of H2O2 (50 mM) could up-regulate the expression of nos by increasing the oxidative stress level of S. vitulinus. At 2 h after treatment, the expression of nos in S. vitulinus was the highest (P < 0.05), and the relative enzyme activity was increased to about 1.5 times that of the untreated. The growth of S. vitulinus was not substantially affected by 50-mM H2O2 treatment (P > 0.05). When H2O2-treated S. vitulinus was inoculated into fermented sausages, the content of nitrosomyoglobin was increased, and the a*-value (indicating redness) was not significantly different from that in the group treated with nitrite (P > 0.05). This study provides a potential method to enhance the ability of S. vitulinus for colourising fermented sausage by inducing the overexpression of nos.

Nitric oxide mediated kisspeptin regulation of steroidogenesis and gametogenesis in the catfish, Clarias batrachus.

Nitric oxide (NO) is a gaseous molecule that regulates various reproductive functions. It is a well-recognized regulator of GnRH-FSH/LH-sex steroid secretion in vertebrates including fish. Kisspeptin is a recently discovered neuropeptide which also regulates GnRH secretion. Nitrergic and kisspeptin neurons are reported in close physical contact in the mammalian brain suggesting their interactive role in the release of GnRH. The existence of kisspeptin and NOS is also demonstrated in vertebrate gonads, but information on their reciprocal relation in gonads, if any, is obscure. Therefore, attempts were made to evaluate the functional reciprocal relation between nitric oxide and kisspeptin in the catfish gonads, if any, by administering the nitric oxide synthase (NOS) inhibitor, L-NAME {N(G)-nitro-L-arginine methyl ester}, which reduces NO production, and kisspeptin agonist (KP-10) and assessing their impacts on the expressions of kisspeptin1, different NOS isoforms, NO and steroid production in the gonadal tissue. The results revealed that L-NAME suppressed the expression of kiss1 in gonads of the catfish establishing the role of NO in kisspeptin expression. However, KP-10 increased the expression of all the isoforms of NOSs (iNOS, eNOS, nNOS) and concurrently NO and steroids in the ovary and testis. In vitro studies also indicate that kisspeptin stimulates the production of NO and estradiol and testosterone levels in the gonadal explants and medium. Thus, in vivo results clearly suggest a reciprocal interaction between kisspeptin and NO to regulate the gonadal activity of the catfish. The in vitro findings further substantiate our contention regarding the interactive role of kisspeptin and NO in gonadal steroidogenesis.

Physiological and Pathophysiological Relevance of Nitric Oxide Synthases (NOS) in Retinal Blood Vessels.

Nitric oxide synthases (NOS) are essential regulators of vascular function, and their role in ocular blood vessels is of paramount importance for maintaining ocular homeostasis. Three isoforms of NOS-endothelial (eNOS), neuronal (nNOS), and inducible (iNOS)-contribute to nitric oxide production in ocular tissues, exerting multifaceted effects on vascular tone, blood flow, and overall ocular homeostasis. Endothelial NOS, primarily located in endothelial cells, is pivotal for mediating vasodilation and regulating blood flow. Neuronal NOS, abundantly found in nerve terminals, contributes to neurotransmitter release and vascular tone modulation in the ocular microvasculature. Inducible NOS, expressed under inflammatory conditions, plays a role in response to pathological stimuli. Understanding the distinctive contributions of these NOS isoforms in retinal blood vessels is vital to unravel the mechanisms underlying various ocular diseases, such diabetic retinopathy. This article delves into the unique contributions of NOS isoforms within the complex vascular network of the retina, elucidating their significance as potential therapeutic targets for addressing pathological conditions.

Hypothermic Oxygenated Perfusion Improves Vascular and Contractile Function by Preserving Endothelial Nitric Oxide Production in Cardiac Grafts Obtained With Donation After Circulatory Death.

BACKGROUND: Cardiac donation after circulatory death is a promising option to increase graft availability. Graft preservation with 30 minutes of hypothermic oxygenated perfusion (HOPE) before normothermic machine perfusion may improve cardiac recovery as compared with cold static storage, the current clinical standard. We investigated the role of preserved nitric oxide synthase activity during HOPE on its beneficial effects. METHODS AND RESULTS: Using a rat model of donation after circulatory death, hearts underwent in situ ischemia (21 minutes), were explanted for a cold storage period (30 minutes), and then reperfused under normothermic conditions (60 minutes) with left ventricular loading. Three cold storage conditions were compared: cold static storage, HOPE, and HOPE with Nω-nitro-L-arginine methyl ester (nitric oxide synthase inhibitor). To evaluate potential confounding effects of high coronary flow during early reperfusion in HOPE hearts, bradykinin was administered to normalize coronary flow to HOPE levels in 2 additional groups (cold static storage and HOPE with Nω-nitro-L-arginine methyl ester). Cardiac recovery was significantly improved in HOPE versus cold static storage hearts, as determined by cardiac output, left ventricular work, contraction and relaxation rates, and coronary flow (P<0.05). Furthermore, HOPE attenuated postreperfusion calcium overload. Strikingly, the addition of Nω-nitro-L-arginine methyl ester during HOPE largely abolished its beneficial effects, even when early reperfusion coronary flow was normalized to HOPE levels. CONCLUSIONS: HOPE provides superior preservation of ventricular and vascular function compared with the current clinical standard. Importantly, HOPE's beneficial effects require preservation of nitric oxide synthase activity during the cold storage. Therefore, the application of HOPE before normothermic machine perfusion is a promising approach to optimize graft recovery in donation after circulatory death cardiac grafts.

Association of impulsive behavior and cerebrospinal fluid/plasma oxidation and antioxidation ratio in Chinese men.

OBJECTIVES: Impulsive behavior is the precursor of many psychiatric and neurological conditions. High levels of impulsive behavior will increase health risk behavior and related injuries. Impulsive behavior is produced and regulated by central and peripheral biological factors, and oxidative stress (OS) can aggravate it. However, previous studies only showed that impulsive behavior was related to the level of the peripheral OS. Therefore, this study aims to clarify the relationship between OS and impulsive behavior in the brain and peripheral blood. METHODS: We recruited 64 Chinese men. We measured superoxide dismutase (SOD) (including copper, zinc and manganese) and nitric oxide synthase (NOS) (including total, inducible and constitutive) in cerebrospinal fluid (CSF) and plasma. The Barratt Impulsiveness Scale version 11 (BIS-11) was used to evaluate impulsive behavior. The relationship between OS and impulsive behavior was evaluated by partial correlation analysis and stepwise multiple regression analysis. RESULTS: Partial correlation analysis showed that the ratio of total NOS-to-MnSOD and iNOS-to-MnSOD in CSF were negatively correlated with the BIS-11 motor scores (r = -0.431, p = -0.001; r = -0.434, p = -0.001). Stepwise multiple regression analysis showed that the ratio of CSF iNOS-to-MnSOD was the most influential variable on the BIS-11 motor scores(ß = -0.434, t = -3.433, 95 %CI(-0.374, -0.098), p = 0.001). CONCLUSIONS AND RELEVANCE: The imbalance of central oxidation and antioxidation is related to impulsive behavior, which broadens our understanding of the correlation between impulsive behavior and OS.

Duodenocolic fistula healing by pentadecapeptide BPC 157 in rats. A cytoprotection viewpoint.

Using duodenocolic fistula in rats, this study attempts to highlight the particular cytoprotection aspects of the healing of fistulas and therapy potential of the stable gastric pentadecapeptide BPC 157, a cytoprotection mediator (i.e. upgrading minor vessels to induce healing at both fistula's sides). Upon duodenocolic fistula creation (two 'perforated' lesions put together) (assessed at 3, 6, 9, 12, and 15 min), BPC 157, given locally at the fistula, or intragastrically (10 µg/kg, 10 ng/kg), rapidly induces vessel 'recruitment', 'running' toward the defect, simultaneously at duodenum and colon, providing numerous collaterals and branching. The mRNA expression studies done at that time provided strongly elevated (nitric oxide synthase 2) and decreased (cyclooxygenase-2, vascular endothelial growth factor A, nitric oxide synthase (NOS)-1, NOS-3, nuclear factor-kappa-B-activating protein) gene expression. As therapy, rats with duodenocolic fistulas, received BPC 157 10 µg/kg, 10 ng/kg, per-orally, in drinking water till sacrifice, or alternatively, intraperitoneally, first application at 30 min after surgery, last at 24 h before sacrifice, at day 1, 3, 7, 14, 21, and 28. Controls exhibited both defects persisting, continuous fistula leakage, diarrhea, continuous weight loss, advanced adhesion formation and intestinal obstruction. Contrary, all BPC 157-treated rats have closed both defects, duodenal and colonic, no fistula leakage (finally, maximal instilled volume corresponds to healthy rats), no cachexia, the same weight as before surgery, no diarrhea, markedly less adhesion formation and intestinal passage obstruction. Thus, BPC 157 regimens resolve the duodenal/colon lesions and duodenocolic fistulas in rats, and rapid vessels recovery appears as the essential point in the implementation of the cytoprotection concept in the fistula therapy.

Immunocytochemical localization of nitric oxide synthase-containing neurons in the visual cortex of the Mongolian gerbil.

INTRODUCTION: Nitric oxide (NO) is present in various cell types in the central nervous system and plays a crucial role in the control of various cellular functions. The diurnal Mongolian gerbil is a member of the rodent family Muridae that exhibits unique physiological, anatomical, and behavioral differences from the nocturnal rat and mouse, which render it a useful model for studying the visual system. The purpose of this study was to confirm the distribution and morphology of neurons that contain nitric oxide synthase (NOS) and their pattern of co-expressing NOS with neuropeptide Y (NPY), somatostatin (SST), and gamma-aminobutyric acid (GABA) in the visual cortex of Mongolian gerbils. MATERIALS AND METHODS: Mongolian gerbils were used in the study. We confirmed the localization of NOS in the visual cortex of Mongolian gerbils using horseradish peroxidase immunocytochemistry, fluorescent immunocytochemistry, and conventional confocal microscopy. RESULTS: NOS-immunoreactive (IR) neurons were present in all layers of the visual cortex of the Mongolian gerbil, with the exception of layer I, with the highest density observed in layer V (50.00%). The predominant type of NOS-IR neurons was multipolar round/oval cells (60.96%). Two-color immunofluorescence revealed that 100% NOS-IR neurons were co-labeled with NPY and SST and 34.55% were co-labeled with GABA. CONCLUSIONS: Our findings of the laminar distribution and morphological characteristics of NOS-IR neurons, as well as the colocalization patterns of NOS-IR neurons with NPY, SST, and GABA, indicated the presence of species-specific differences, suggesting the functional diversity of NO in the visual cortex. This study provides valuable data on the anatomical organization of NOS-IR neurons and, consequently, a better understanding of the functional aspects of NO and species diversity.

Association between nitric oxide synthase (NOS3) gene polymorphisms and diabetic nephropathy: An updated meta-analysis.

Polymorphisms located within NOS3 gene have been investigated as susceptibility variants for diabetic nephropathy (DN) in type 2 diabetes mellitus (T2DM) in a large number of studies. However, these previous articles yielded inconsistent results and we aimed at elucidating the impact of NOS3 variants on DN risk in T2DM by conducting an updated systematic data synthesis. A total of 36 studies (12,807 participants) were selected for qualitative data synthesis, while 33 records with 11,649 subjects were included in the meta-analysis. The pooled analysis demonstrated the association of minor alleles of rs2070744 and rs1799983 with an increased susceptibility to DN (P < 0.001 and P = 0.015 for allelic model, respectively). For both of these variants, a significant effect of subgrouping according to ethnicity was found. Rs869109213 displayed an association with DN susceptibility, with pooled effect measures indicating a predisposing effect of the minor allele a (Prec = 0.002, ORrec = 1.960, 95%CI 1.288-2.983; Paavs. bb = 0.001, ORaavs. bb = 2.014, 95%CI 1.316-3.083). These findings support the effects of NOS3 variants on the risk of developing DN in T2DM.

Cell constriction requires processive septal peptidoglycan synthase movement independent of FtsZ treadmilling in Staphylococcus aureus.

Bacterial cell division requires recruitment of peptidoglycan (PG) synthases to the division site by the tubulin homologue, FtsZ. Septal PG synthases promote septum growth. FtsZ treadmilling is proposed to drive the processive movement of septal PG synthases and septal constriction in some bacteria; however, the precise mechanisms spatio-temporally regulating PG synthase movement and activity and FtsZ treadmilling are poorly understood. Here using single-molecule imaging of division proteins in the Gram-positive pathogen Staphylococcus aureus, we showed that the septal PG synthase complex FtsW/PBP1 and its putative activator protein, DivIB, move with similar velocity around the division site. Impairing FtsZ treadmilling did not affect FtsW or DivIB velocities or septum constriction rates. Contrarily, PG synthesis inhibition decelerated or stopped directional movement of FtsW and DivIB, and septum constriction. Our findings suggest that a single population of processively moving FtsW/PBP1 associated with DivIB drives cell constriction independently of FtsZ treadmilling in S. aureus.

The acute neurotoxicity of inorganic mercury in Mactra chinensis philippi.

Inorganic mercury (IHg) is hazardous to marine organisms especially resulting in neurotoxicity, bivalves are sensitive to pollutants as "ocean sentinel", but data on the neurotoxicity of IHg in bivalves are sparse. So we chosed M. chinensis philippi with typical neural structures in bivalves to investigate the neurotoxicity of IHg, which could be helpful to understand the specificity of neural regulation and the response characteristics of bivalves. After acute exposed to IHg (HgCl2) for 24 h, the metabolites of ganglion tissues in M. chinensis philippi were evaluated using 1H-nuclear magnetic resonance based metabolomics; Ca2+, neurotransmitters (nitric oxide, glutamate, acetylcholine) and related enzymes (calcineurin, nitric oxide synthase and acetylcholinesterase) were measured using biochemical detection. Compared to the control group, the levels of the nitric oxide (81.04 ± 12.84 µmol/g prot) and acetylcholine (30.93 ± 12.57 µg/mg prot) in M. chinensis philippi of IHg-treated were decreased, while glutamate (2.11 ± 0.61 mmol/L) increased significantly; the activity of nitric oxide synthase (679.34 ± 135.33 U/mg prot) was increased, while acetylcholinesterase (1.39 ± 0.44 U/mg prot) decreased significantly, and the activity of calcineurin (0.52 ± 0.02 U/mg prot) had a statistically insignificant increasing tendency. The concentration of Ca2+ (0.92 ± 0.46 mmol/g prot) in the IHg-treated group was significantly higher than that in the control group. OPLS-DA was performed to reveal the difference in metabolites between the control and IHg-challenged groups, the metabolites of glucose, glutamine, inosine, succinate, glutamate, homarine, and alanine were sensitive to IHg, subsequently metabolic pathways that were affected including glucose metabolism, glutamine metabolism, nucleotide metabolism, Krebs cycle, amino acid metabolism and osmotic regulation. In our study, IHg interfered with metabolites in M. chinensis philippi, thus the corresponding metabolic pathways were changed, which influenced the neurotransmitters subsequently. Furthermore, Ca2+overload affected the synthesis or degradation of the neurotransmitters, and then the altered neurotransmitters involved in changes in metabolic pathways again. Overall, we hypothesized that the neurotoxic effects of IHg on bivalve were in close contact with metabolism, neurotransmitters, related enzymes and Ca2+, which could be effective neurotoxic biomarkers for marine environmental quality assessment, and also provide effective data for the study of the regulatory mechanism of the nervous system in response to IHg in bivalves.

Role of induced nitric oxide synthases in orofacial nociception/discomfort after dental tooth bleaching with hydrogen peroxide.

OBJECTIVE: To evaluate the role of induced nitric oxide synthase (iNOS) in nociception/orofacial discomfort in rats submitted to tooth whitening with hydrogen peroxide (H2O2). DESIGN: Wistar rats were divided into three groups (n = 24/group): a sham group not submitted to whitening treatment, a saline group submitted to whitening treatment, and a test group submitted to whitening treatment and blockade of iNOS with aminoguanidine 50 mg/kg/day. After 24 and 48 h, and 7 days, the animals were euthanized to collect trigeminal ganglia and maxillae to histomorphometric analysis (size of neuronal bodies and percentage of pulp area filled by vessels) and behavior/nociception (Grimace scales, scratching and biting counting, weight loss and nociception assay). ANOVA-1- or - 2-way tests were used (p < 0.05, GraphPadPrism 5.0). RESULTS: The aminoguanidine-treated group showed a reduction in nociceptive threshold in the masseteric region (p < 0.001), Grimace scale scores (p < 0.001), number of scratching (p = 0.011) and body mass loss (p = 0.007). After 24 and 48 h of tooth bleaching, the saline group showed a significant increase in the mean area of the blood vessels (p = 0.020) and iNOS immunostaining in odontoblasts (p = 0.002) and non-odontoblasts cells (p = 0.025). Aminoguanidine reversed both increases. Tooth bleaching reduced the mean area of neuronal bodies, and aminoguanidine significantly reversed it (p = 0.019), but an increase in GFAP immunostaining in neuronal bodies did not reduce after seven-days or after aminoguanidine treatment (p = 0.003). CONCLUSION: iNOS blockage by aminoguanidine plays an important role in nociception and orofacial discomfort by control of inflammation in dental pulp after tooth bleaching with hydrogen peroxide (H2O2) 35%.

Influence of pallet rich plasma, quercetin and their combination on activity of nitric oxide cycle enzymes in nasal mucosa of patients with atrophic rhinitis.

OBJECTIVE: Aim: To study the general activity of NO synthases (gNOS), the activity of inducible and constitutive isoforms of NO synthase, the activity of arginases, and the concentration of nitrites in the nasal mucosa under the conditions of local treatment of chronic atrophic rhinitis (AR) with quercetin and platelet-rich plasma (PRP therapy).. PATIENTS AND METHODS: Materials and Methods: The study was conducted on 118 patients divided into two groups: control (n=20) and experimental (patients with AR, n=98). Experimental group was divided into 4 subgroups: standard treatment (n=29), PRP therapy (6 injections for 28 day course, n=19), Quercetin (40 mg 3 times a day for 28 days, n=26) and PRP+Quercetin (n=24) groups. RESULTS: Results: Standard therapy of SaR increases gNOS by 278.38% and arginase activity increases by 222.73%. PRP therapy increases gNOS by 211.43% and arginase by 540.91%. Quercetin elevates gNOS by 108.33% and arginase by 250%. PRP therapy and quercetin increases gNOS by 146.15% and arginase by 536.36%. CONCLUSION: Conclusions: The use of standard therapy of SaR and addition of PRP therapy, quercetin and their combination effectively restores the production of nitric oxide and the arginase activity in the nasal mucosa.

S-nitrosylation-triggered unfolded protein response maintains hematopoietic progenitors in Drosophila.

The Drosophila lymph gland houses blood progenitors that give rise to myeloid-like blood cells. Initially, blood progenitors proliferate, but later, they become quiescent to maintain multipotency before differentiation. Despite the identification of various factors involved in multipotency maintenance, the cellular mechanism controlling blood progenitor quiescence remains elusive. Here, we identify the expression of nitric oxide synthase in blood progenitors, generating nitric oxide for post-translational S-nitrosylation of protein cysteine residues. S-nitrosylation activates the Ire1-Xbp1-mediated unfolded protein response, leading to G2 cell-cycle arrest. Specifically, we identify the epidermal growth factor receptor as a target of S-nitrosylation, resulting in its retention within the endoplasmic reticulum and blockade of its receptor function. Overall, our findings highlight developmentally programmed S-nitrosylation as a critical mechanism that induces protein quality control in blood progenitors, maintaining their undifferentiated state by inhibiting cell-cycle progression and rendering them unresponsive to paracrine factors.

Role of neutrophil myeloperoxidase in the development and progression of high-altitude pulmonary edema.

BACKGROUND: Neutrophil infiltration and hypoxic pulmonary vasoconstriction induced by hypobaric hypoxic stress are vital in high-altitude pulmonary edema (HAPE). Myeloperoxidase (MPO), an important enzyme in neutrophils, is associated with inflammation and oxidative stress and is also involved in the regulation of nitric oxide synthase (NOS), an enzyme that catalyzes the production of the vasodilatory factor nitric oxide (NO). However, the role of neutrophil MPO in HAPE's progression is still uncertain. Therefore, we hypothesize that MPO is involved in the development of HAPE via NOS. METHODS: In Xining, China (altitude: 2260 m), C57BL/6 N wild-type and mpo-/- mice served as normoxic controls, while a hypobaric chamber simulated 7000 m altitude for hypoxia. L-NAME, a nitric oxide synthase (NOS) inhibitor to inhibit NO production, was the experimental drug, and D-NAME, without NOS inhibitory effects, was the control. After measuring pulmonary artery pressure (PAP), samples were collected and analyzed for blood neutrophils, oxidative stress, inflammation, vasoactive substances, pulmonary alveolar-capillary barrier permeability, and lung tissue morphology. RESULTS: Wild-type mice's lung injury scores, permeability, and neutrophil counts rose at 24 and 48 h of hypoxia exposure. Under hypoxia, PAP increased from 12.89 ± 1.51 mmHg under normoxia to 20.62 ± 3.33 mmHg significantly in wild-type mice and from 13.24 ± 0.79 mmHg to 16.50 ± 2.07 mmHg in mpo-/- mice. Consistent with PAP, inducible NOS activity, lung permeability, lung injury scores, oxidative stress response, and inflammation showed more significant increases in wild-type mice than in mpo-/- mice. Additionally, endothelial NOS activity and NO levels decreased more pronouncedly in wild-type mice than in mpo-/- mice. NOS inhibition during hypoxia led to more significant increases in PAP, permeability, and lung injury scores compared to the drug control group, especially in wild-type mice. CONCLUSION: MPO knockout reduces oxidative stress and inflammation to preserve alveolar-capillary barrier permeability and limits the decline in endothelial NOS activity to reduce PAP elevation during hypoxia. MPO inhibition emerges as a prospective therapeutic strategy for HAPE, offering avenues for precise interventions.

Disruption of an Active Site Network Leads to Activation of C2α-Lactylthiamin Diphosphate on the Antibacterial Target 1-Deoxy-d-xylulose-5-phosphate Synthase.

The bacterial metabolic enzyme 1-deoxy-d-xylulose-5-phosphate synthase (DXPS) catalyzes the thiamin diphosphate (ThDP)-dependent formation of DXP from pyruvate and d-glyceraldehyde-3-phosphate (d-GAP). DXP is an essential bacteria-specific metabolite that feeds into the biosynthesis of isoprenoids, pyridoxal phosphate (PLP), and ThDP. DXPS catalyzes the activation of pyruvate to give the C2α-lactylThDP (LThDP) adduct that is long-lived on DXPS in a closed state in the absence of the cosubstrate. Binding of d-GAP shifts the DXPS-LThDP complex to an open state which coincides with LThDP decarboxylation. This gated mechanism distinguishes DXPS in ThDP enzymology. How LThDP persists on DXPS in the absence of cosubstrate, while other pyruvate decarboxylases readily activate LThDP for decarboxylation, is a long-standing question in the field. We propose that an active site network functions to prevent LThDP activation on DXPS until the cosubstrate binds. Binding of d-GAP coincides with a conformational shift and disrupts the network causing changes in the active site that promote LThDP activation. Here, we show that the substitution of putative network residues, as well as nearby residues believed to contribute to network charge distribution, predictably affects LThDP reactivity. Substitutions predicted to disrupt the network have the effect to activate LThDP for decarboxylation, resulting in CO2 and acetate production. In contrast, a substitution predicted to strengthen the network fails to activate LThDP and has the effect to shift DXPS toward the closed state. Network-disrupting substitutions near the carboxylate of LThDP also have a pronounced effect to shift DXPS to an open state. These results offer initial insights to explain the long-lived LThDP intermediate and its activation through disruption of an active site network, which is unique to DXPS. These findings have important implications for DXPS function in bacteria and its development as an antibacterial target.

The Promiscuity of Squalene Synthase-Like Enzyme: Dehydrosqualene Synthase, a Natural Squalene Hyperproducer?

Dehydrosqualene synthase (CrtM), as a squalene synthase-like enzyme from Staphylococcus aureus, can naturally utilize farnesyl diphosphate to produce dehydrosqualene (C30H48). However, no study has documented the natural production of squalene (C30H50) by CrtM. Here, based on an HPLC-Q-Orbitrap-MS/MS study, we report that the expression of crtM in vitro or in Bacillus subtilis 168 both results in the output of squalene, dehydrosqualene, and phytoene (C40H64). Notably, wild-type CrtM exhibits a significantly higher squalene yield compared to squalene synthase (SQS) from Bacillus megaterium with an approximately 2.4-fold increase. Moreover, the examination of presqualene diphosphate's stereostructures in both CrtM and SQS enzymes provides further understanding into the presence of multiple identified terpenoids. In summary, this study not only provides insights into the promiscuity demonstrated by squalene synthase-like enzymes but also highlights a new strategy of utilizing CrtM as a potential replacement for SQS in cell factories, thereby enhancing squalene production.