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%.

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.

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.

Asymmetric Dimethylarginine Enables Depolarizing Spikes and Vasospasm in Mesenteric and Coronary Resistance Arteries

BACKGROUND

Increased vasoreactivity due to reduced endothelial NO bioavailability is an underlying feature of cardiovascular disease, including hypertension. In small resistance arteries, declining NO enhances vascular smooth muscle (VSM) reactivity partly by enabling rapid depolarizing Ca2+-based spikes that underlie vasospasm. The endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) is metabolized by DDAH1 (dimethylarginine dimethylaminohydrolase 1) and elevated in cardiovascular disease. We hypothesized ADMA might enable VSM spikes and vasospasm by reducing NO bioavailability, which is opposed by DDAH1 activity and L-arginine.

METHODS

Rat isolated small mesenteric arteries and myogenic rat-isolated intraseptal coronary arteries (RCA) were studied using myography, VSM intracellular recording, Ca2+ imaging, and DDAH1 immunolabeling. Exogenous ADMA was used to inhibit NO synthase and a selective DDAH1 inhibitor, NG-(2-methoxyethyl) arginine, to assess the functional impact of ADMA metabolism.

RESULTS

ADMA enhanced rat-isolated small mesenteric arteries vasoreactivity to the α1-adrenoceptor agonist, phenylephrine by enabling T-type voltage-gated calcium channel-dependent depolarizing spikes. However, some endothelium-dependent NO-vasorelaxation remained, which was sensitive to DDAH1-inhibition with NG-(2-methoxyethyl) arginine. In myogenically active RCA, ADMA alone stimulated depolarizing Ca2+ spikes and marked vasoconstriction, while NO vasorelaxation was abolished. DDAH1 expression was greater in rat-isolated small mesenteric arteries endothelium compared with RCA, but low in VSM of both arteries. L-arginine prevented depolarizing spikes and protected NO-vasorelaxation in rat-isolated small mesenteric artery and RCA.

CONCLUSIONS

ADMA increases VSM electrical excitability enhancing vasoreactivity. Endothelial DDAH1 reduces this effect, and low levels of DDAH1 in RCAs may render them susceptible to endothelial dysfunction contributing to vasospasm, changes opposed by L-arginine.

Nitric oxide synthase expression in Pseudomonas koreensis MME3 improves plant growth promotion traits

The development of novel biotechnologies that promote a better use of N to optimize crop yield is a central goal for sustainable agriculture. Phytostimulation, biofertilization, and bioprotection through the use of bio-inputs are promising technologies for this purpose. In this study, the plant growth-promoting rhizobacteria Pseudomonas koreensis MME3 was genetically modified to express a nitric oxide synthase of Synechococcus SyNOS, an atypical enzyme with a globin domain that converts nitric oxide to nitrate. A cassette for constitutive expression of synos was introduced as a single insertion into the genome of P. koreensis MME3 using a miniTn7 system. The resulting recombinant strain MME3:SyNOS showed improved growth, motility, and biofilm formation. The impact of MME3:SyNOS inoculation on Brachypodium distachyon growth and N uptake and use efficiencies under different N availability situations was analyzed, in comparison to the control strain MME3:c. After 35 days of inoculation, plants treated with MME3:SyNOS had a higher root dry weight, both under semi-hydroponic and greenhouse conditions. At harvest, both MME3:SyNOS and MME3:c increased N uptake and use efficiency of plants grown under low N soil. Our results indicate that synos expression is a valid strategy to boost the phytostimulatory capacity of plant-associated bacteria and improve the adaptability of plants to N deficiency. KEY POINTS: • synos expression improves P. koreensis MME3 traits important for rhizospheric colonization • B. distachyon inoculated with MME3:SyNOS shows improved root growth • MME3 inoculation improves plant N uptake and use efficiencies in N-deficient soil.

Mechanistic characterisation of a sesquiterpene synthase for asterisca-1,6-diene from the liverwort Radula lindenbergiana and implications for pentalenene biosynthesis

A sesquiterpene synthase from the liverwort Radula lindenbergiana was characterised and shown to produce the new sesquiterpene hydrocarbon (3R,9R)-asterisca-1,6-diene, besides small amounts of pentalenene. The biosynthesis of asterisca-1,6-diene was studied through isotopic labelling experiments, giving additional insights into the long discussed biosynthesis of pentalenene.

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.

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.

Terpene Synthase Gene Family in Chinese Chestnut (Castanea mollissima BL.) Harbors Two Sesquiterpene Synthase Genes Implicated in Defense against Gall Wasp Dryocosmus kuriphilus

Chinese chestnut (Castanea mollissima BL.) is a well-known fruit tree that has been cultivated in East Asia for millennia. Leaves and buds of the plant can become seriously infested by the gall wasp Dryocosmus kuriphilus (GWDK), which results in gall formation and associated significant losses in fruit production. Herbivore-induced terpenes have been reported to play an important role in plant-herbivory interactions, and in this study, we show that upon herbivory by GWDK, four terpene-related compounds were significantly induced, while the concentrations of these four compounds in intact buds were relatively low. Among these compounds, (E)-nerolidol and (E, E)-α-farnesene have frequently been reported to be involved in plant herbivory defenses, which suggests direct and/or indirect functions in chestnut GWDK defenses. Candidate terpene synthase (TPS) genes that may account for (E)-nerolidol and (E, E)-α-farnesene terpene biosynthesis were characterized by transcriptomics and phylogenetic approaches, which revealed altered transcript levels for two TPSs: CmAFS, a TPS-g subfamily member, and CmNES/AFS, a TPS-b clade member. Both genes were dramatically upregulated in gene expression upon GWDK infestation. Furthermore, Agrobacterium tumefaciens-mediated transient overexpression in Nicotiana benthamiana showed that CmAFS catalyzed the formation of (E, E)-α-farnesene, while CmNES/AFS showed dual (E)-nerolidol and (E, E)-α-farnesene synthase activity. Biochemical assays of the recombinant CmAFS and CmNES/AFS proteins confirmed their catalytic activity in vitro, and the enzymatic products were consistent with two of the major volatile compounds released upon GWDK-infested chestnut buds. Subcellular localization demonstrated that CmAFS and CmNES/AFS were both localized in the cytoplasm, the primary compartment for sesquiterpene synthesis. In summary, we show that two novel sesquiterpene synthase genes CmAFS and CmNES/AFS are inducible by herbivory and can account for the elevated accumulation of (E, E)-α-farnesene and (E)-nerolidol upon GWDK infestation and may be implicated in chestnut defense against GWDK herbivores.

Sequence-Structure Analysis Unlocking the Potential Functional Application of the Local 3D Motifs of Plant-Derived Diterpene Synthases

Plant-derived diterpene synthases (PdiTPSs) play a critical role in the formation of structurally and functionally diverse diterpenoids. However, the specificity or functional-related features of PdiTPSs are not well understood. For a more profound insight, we collected, constructed, and curated 199 functionally characterized PdiTPSs and their corresponding 3D structures. The complex correlations among their sequences, domains, structures, and corresponding products were comprehensively analyzed. Ultimately, our focus narrowed to the geometric arrangement of local structures. We found that local structural alignment can rapidly localize product-specific residues that have been validated by mutagenesis experiments. Based on the 3D motifs derived from the residues around the substrate, we successfully searched diterpene synthases (diTPSs) from the predicted terpene synthases and newly characterized PdiTPSs, suggesting that the identified 3D motifs can serve as distinctive signatures in diTPSs (I and II class). Local structural analysis revealed the PdiTPSs with more conserved amino acid residues show features unique to class I and class II, whereas those with fewer conserved amino acid residues typically exhibit product diversity and specificity. These results provide an attractive method for discovering novel or functionally equivalent enzymes and probing the product specificity in cases where enzyme characterization is limited.

The Ethylene Biosynthetic Enzymes, 1-Aminocyclopropane-1-Carboxylate (ACC) Synthase (ACS) and ACC Oxidase (ACO): The Less Explored Players in Abiotic Stress Tolerance

Ethylene is an essential plant hormone, critical in various physiological processes. These processes include seed germination, leaf senescence, fruit ripening, and the plant's response to environmental stressors. Ethylene biosynthesis is tightly regulated by two key enzymes, namely 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxidase (ACO). Initially, the prevailing hypothesis suggested that ACS is the limiting factor in the ethylene biosynthesis pathway. Nevertheless, accumulating evidence from various studies has demonstrated that ACO, under specific circumstances, acts as the rate-limiting enzyme in ethylene production. Under normal developmental processes, ACS and ACO collaborate to maintain balanced ethylene production, ensuring proper plant growth and physiology. However, under abiotic stress conditions, such as drought, salinity, extreme temperatures, or pathogen attack, the regulation of ethylene biosynthesis becomes critical for plants' survival. This review highlights the structural characteristics and examines the transcriptional, post-transcriptional, and post-translational regulation of ACS and ACO and their role under abiotic stress conditions. Reviews on the role of ethylene signaling in abiotic stress adaptation are available. However, a review delineating the role of ACS and ACO in abiotic stress acclimation is unavailable. Exploring how particular ACS and ACO isoforms contribute to a specific plant's response to various abiotic stresses and understanding how they are regulated can guide the development of focused strategies. These strategies aim to enhance a plant's ability to cope with environmental challenges more effectively.

Traditional Chinese Medicine formula Wubi Shanyao Pills protects against reproductive aging by activating SIRT1/3 to reduce apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

The study of male reproductive aging and its associated concerns holds significant importance within the realm of health issues affecting the elderly population. Wubi Shanyao Pills (WSP), a traditional Chinese patent medicine originating from the Tang Dynasty, has been recognized for its ability to enhance male sexual functions while also tonifying the kidney and spleen. Nevertheless, the precise effects and underlying mechanisms through which WSP ameliorates the decline in reproductive function among aging men remain uncertain.

AIM OF THE STUDY

This study elucidated the distinctive impacts of WSP on ameliorating the decline in reproductive function caused by natural aging, as well as its underlying mechanisms.

MATERIALS AND METHODS

Initially, male mice at the age of 15 months were administered WSP orally at doses of 0.375, 0.75, and 1.50 g/kg per day for a duration of 8 consecutive weeks. The impact of WSP on age-related manifestations in naturally aging mice was assessed based on their behavioral performance. The renal function of the mice was evaluated by measuring serum biochemical indicators, including Creatinine (CR), Uric acid (UA), and Blood urea nitrogen (BUN). Additionally, Superoxide dismutase (SOD) and Malonaldehyde (MDA) levels in renal tissue were determined using applied chemistry methods. Then assessed the levels of Nitric oxide (NO), Total nitric oxide synthase (T-NOS), Guanosine cyclase (GC), and Cyclic guanosine monophosphate (cGMP) in the penile tissue, as well as the expression of Endothelial nitric oxide synthase (eNOS) and Guanylate Cyclase Activator (GUCA) protein, in order to investigate the erectile function of the penis. Additionally, the quality of epididymal sperm was examined using an electron microscope. Furthermore, the serum sex hormone level and related protein expression were determined through the utilization of enzyme-linked immunosorbent assay and immunohistochemistry techniques. Pathological alterations and the ultrastructure of the testis were investigated using hematoxylin-eosin staining and transmission electron microscopy. Subsequently, the apoptosis of spermatogenic cells in the testes was assessed employing TUNEL, immunofluorescence, western blotting, and quantitative real-time polymerase chain reaction.

RESULTS

The administration of WSP has been found to enhance the behavioral performance and sexual behavior in aged mice. It's also could increase in serum levels of CR, UA, and BUN, as well as the elevation of SOD activity in kidney tissue, which subsequently leads to a reduction in MDA levels and an improvement in the structural damage caused by aging in the kidney tissue. Consequently, the renal function is enhanced. Additionally, WSP has been observed to elevate the levels of NO, T-NOS, GC, and cGMP in penile tissue, along with an increase in eNOS and GUCA protein expression, indicating an improvement in penile erectile function. The administration of WSP resulted in a decrease in the occurrence of programmed cell death in testicular germ cells, leading to an enhancement in sperm quality and the overall function of testicular spermatogenesis. This improvement can be attributed to the modulation of hormone levels and the regulation of SIRT1/3, p53, FOXO3, Bax, and Caspase-3 expression.

CONCLUSION

Collectively, our findings indicate that the administration of WSP has the potential to impede the occurrence of programmed cell death in testicular cells by modulating the expression of SIRT1/3 and subsequent genes associated with apoptosis. Consequently, this regulatory mechanism facilitates the proliferation of testicular cells and sustains the spermatogenic function of the testes. Consequently, by modulating the levels of sexual hormones in naturally aging mice, WSP ultimately enhances the quality of sperm and reproductive function. Concurrently, it also ameliorates age-related behavioral changes, renal function, and erectile function.

Oxysterols in Central and Peripheral Synaptic Communication

Cholesterol is a key molecule for synaptic transmission, and both central and peripheral synapses are cholesterol rich. During intense neuronal activity, a substantial portion of synaptic cholesterol can be oxidized by either enzymatic or non-enzymatic pathways to form oxysterols, which in turn modulate the activities of neurotransmitter receptors (e.g., NMDA and adrenergic receptors), signaling molecules (nitric oxide synthases, protein kinase C, liver X receptors), and synaptic vesicle cycling involved in neurotransmitters release. 24-Hydroxycholesterol, produced by neurons in the brain, could directly affect neighboring synapses and change neurotransmission. 27-Hydroxycholesterol, which can cross the blood-brain barrier, can alter both synaptogenesis and synaptic plasticity. Increased generation of 25-hydroxycholesterol by activated microglia and macrophages could link inflammatory processes to learning and neuronal regulation. Amyloids and oxidative stress can lead to an increase in the levels of ring-oxidized sterols and some of these oxysterols (4-cholesten-3-one, 5α-cholestan-3-one, 7β-hydroxycholesterol, 7-ketocholesterol) have a high potency to disturb or modulate neurotransmission at both the presynaptic and postsynaptic levels. Overall, oxysterols could be used as "molecular prototypes" for therapeutic approaches. Analogs of 24-hydroxycholesterol (SGE-301, SGE-550, SAGE718) can be used for correction of NMDA receptor hypofunction-related states, whereas inhibitors of cholesterol 24-hydroxylase, cholestane-3β,5α,6β-triol, and cholest-4-en-3-one oxime (olesoxime) can be utilized as potential anti-epileptic drugs and (or) protectors from excitotoxicity.

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.

NRF2 interacts with distal enhancer and inhibits nitric oxide synthase 2 expression in KRAS-driven pancreatic cancer cells

Nitric oxide is a pleiotropic free radical produced by three nitric oxide synthases (NOS1-3), of which inducible NOS2 is involved in tumor initiation and progression. In this study, RNA-seq, ChIP-seq and qRT-PCR experiments combined with bioinformatic analyses showed that NRF2 is a repressor of NOS2 gene by maintaining a distal enhancer located 22 kb downstream of TSS in an inactive state. Deletion of NRF2 leads to activation of the enhancer, which exerts a pioneering function before it is fully activated. Specifically, NRF2 controls the expression of NOS2 in response to intracellular oxidative stress and extracellular oxygen pressure. We found that abrogation of NOS2 expression by siRNAs partially reduced the ability of WT Panc-1 cells to form 3D spheroids, but strongly reduced the formation of 3D spheroids by NRF2-depleted Panc-1 cells. Mechanistically, this effect correlates with the finding that NOS2 and nitric oxide stimulate epithelial-to-mesenchymal transition in NRF2-depleted Panc-1 and MIA PaCa-2 cells. We also found that knockdown of NOS2 leads to blockade of 3D matrigel invasion of NRF2-depleted PDAC cells, demonstrating that a short-circuit in the reciprocal regulation of NOS2 and NRF2 attenuates the malignancy of PDAC cells. In summary, we show for the first time that: (i) NRF2 is a suppressor of NOS2 in pancreatic cancer cells; (ii) NRF2 binds to and inactivates an enhancer located 22 kb downstream of TSS of the NOS2 gene; (iii) activation of NOS2 requires suppression of NRF2; (iv) NOS2 is required for NRF2-depleted Panc-1 cells to maintain their malignancy and invasiveness.

Myoendothelial feedback in mouse mesenteric resistance arteries is similar between the sexes, dependent on nitric oxide synthase, and independent of TPRV4

Myoendothelial feedback (MEF), the endothelium-dependent vasodilation following sympathetic vasoconstriction (mediated by smooth muscle to endothelium gap junction communication), has been well studied in resistance arteries of males, but not females. We hypothesized that MEF responses would be similar between the sexes, but different in the relative contribution of the underlying nitric oxide and hyperpolarization mechanisms, given that these mechanisms differ between the sexes in agonist-induced endothelium-dependent dilation. We measured MEF responses (diameter changes) of male and female first- to second-order mouse mesenteric arteries to phenylephrine (10 µM) over 30 min using isolated pressure myography ± blinded inhibition of nitric oxide synthase (NOS) using Nω-nitro-l-arginine methyl ester (l-NAME; 0.1-1.0 mM), hyperpolarization using 35 mM KCl, or transient receptor potential vanilloid 4 (TRPV4) channels using GSK219 (0.1-1.0 µM) or RN-1734 (30 µM). MEF was similar [%dilation (means ± SE): males = 26.7 ± 2.0 and females = 26.1 ± 1.9 at 15 min] and significantly inhibited by l-NAME (1.0 mM) at 15 min [%dilation (means ± SE): males = 8.2 ± 3.3, P < 0.01; females = 6.8 ± 1.9, P < 0.001] and over time (P < 0.01) in both sexes. l-NAME (0.1 mM) + 35 mM KCl nearly eliminated MEF in both sexes (P < 0.001-0.0001). Activation of TRPV4 with GSK101 (0.1-10 µM) induced similar dilation between the sexes. Inhibition of TRPV4, which is reportedly involved in the hyperpolarization mechanism, did not inhibit MEF in either sex. Similar expression of eNOS was found between the sexes with Western blot. Thus, MEF is prominent and similar in murine first- and second-order mesenteric resistance arteries of both sexes, and reliant primarily on NOS and secondarily on hyperpolarization, but not TRPV4.NEW & NOTEWORTHY We found that female mesenteric resistance arteries have similar postconstriction dilatory responses (i.e., myoendothelial feedback) to a sympathetic neurotransmitter analog as male arteries. Both sexes use nitric oxide synthase (NOS) and hyperpolarization, but not TRPV4, in this response. Moreover, the key protein involved in this pathway (eNOS) is similarly expressed in these arteries between the sexes. These similarities are surprising given that agonist-induced endothelium-dependent dilatory mechanisms differ in these arteries between the sexes.

Cimetidine Does Not Inhibit 5-Aminolevulinic Acid Synthase or Heme Oxygenase Activity: Implications for Treatment of Acute Intermittent Porphyria and Erythropoietic Protoporphyria

Acute intermittent porphyria (AIP) is characterized by acute neurovisceral attacks that are precipitated by the induction of hepatic 5-aminolevulinic acid synthase 1 (ALAS1). In erythropoietic protoporphyria (EPP), sun exposure leads to skin photosensitivity due to the overproduction of photoreactive porphyrins in bone marrow erythroid cells, where heme synthesis is primarily driven by the ALAS2 isozyme. Cimetidine has been suggested to be effective for the treatment of both AIP and EPP based on limited case reports. It has been proposed that cimetidine acts by inhibiting ALAS activity in liver and bone marrow for AIP and EPP, respectively, while it may also inhibit the hepatic activity of the heme catabolism enzyme, heme oxygenase (HO). Here, we show that cimetidine did not significantly modulate the activity or expression of endogenous ALAS or HO in wildtype mouse livers or bone marrow. Further, cimetidine did not effectively decrease hepatic ALAS activity or expression or plasma concentrations of the putative neurotoxic porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), which were all markedly elevated during an induced acute attack in an AIP mouse model. These results show that cimetidine is not an efficacious treatment for acute attacks and suggest that its potential clinical benefit for EPP is not via ALAS inhibition.

Suppressive effect of nitric oxide synthase (NOS) inhibitor L-NMMA acetate on choroidal fibrosis in experimental myopic guinea pigs through the nitric oxide signaling pathway

Myopia is one of the most prevalent eye diseases that seriously threaten the eyesight of children and adolescents worldwide. However, the pathogenesis is still unclear, and effective drugs are still scarce. In the present study, the guinea pigs were randomly divided into a normal control (NC) group, a lens-induced myopia (LIM) group, a NOS inhibitor (L-NMMA) injection group, and a NOS inhibitor solvent phosphate-buffered saline (PBS) group and the animals received relevant treatments. After 2- and 4-week different treatments, we noted that the refraction and choroidal thickness in the LIM group decreased compared with the NC group, whereas the ocular axial length increased significantly, and the choroid showed a fibrotic trend. The expression of NOS1, NOS3, TGF-β1, COLI, and α-SMA at gene and protein levels was increased significantly in the choroid (all P < 0.05). After intravitreal injection of NOS inhibitor L-NMMA, we found that compared with the LIM group, the refraction and the choroidal thickness significantly increased, whereas the axial length reduced significantly, accompanied by an increase of choroidal thickness and an improvement of choroidal fibrosis. The expression levels of choroidal NOS1, NOS3, TGF-β, COLI, and α-SMA were significantly reduced (all P < 0.05). In conclusion, the trend of choroidal fibrosis in LIM guinea pigs is positively correlated with the increase in axial length. The NOS inhibitor L-NMMA can alleviate the process of choroidal fibrosis in myopic guinea pigs by inhibiting NO signaling pathway.

An oral glucose tolerance test does not affect cerebral blood flow: role of NOS

Animal data indicate that insulin triggers a robust nitric oxide synthase (NOS)-mediated dilation in cerebral arteries similar to the peripheral tissue vasodilation observed in healthy adults. Insulin's role in regulating cerebral blood flow (CBF) in humans remains unclear but may be important for understanding the links between insulin resistance, diminished CBF, and poor brain health outcomes. We tested the hypothesis that an oral glucose challenge (oral glucose tolerance test, OGTT), which increases systemic insulin and glucose, would acutely increase CBF in healthy adults due to NOS-mediated vasodilation, and that changes in CBF would be greater in anterior regions where NOS expression or activity may be greater. In a randomized, single-blind approach, 18 young healthy adults (24 ± 5 yr) underwent magnetic resonance imaging (MRI) with a placebo before and after an OGTT (75 g glucose), and 11 of these adults also completed an NG-monomethyl-l-arginine (l-NMMA) visit. Four-dimensional (4-D) flow MRI quantified macrovascular CBF and arterial spin labeling (ASL) quantified microvascular perfusion. Subjects completed baseline imaging with a placebo (or l-NMMA), then consumed an OGTT followed by MRI scans and blood sampling every 10-15 min for 90 min. Contrary to our hypothesis, total CBF (P = 0.17) and global perfusion (P > 0.05) did not change at any time point up to 60 min after the OGTT, and no regional changes were detected. l-NMMA did not mediate any effect of OGTT on CBF. These data suggest that insulin-glucose challenge does not acutely alter CBF in healthy adults.

The structural and functional investigation into an unusual nitrile synthase

The biosynthesis of neurotoxin aetokthonotoxin (AETX) that features a unique structure of pentabrominated biindole nitrile involves a first-of-its-kind nitrile synthase termed AetD, an enzyme that shares very low sequence identity to known structures and catalyzes an unprecedented mechanism. In this study, we resolve the crystal structure of AetD in complex with the substrate 5,7-di-Br-L-Trp. AetD adopts the heme oxygenase like fold and forms a hydrophobic cavity within a helical bundle to accommodate the indole moiety. A diiron cluster comprising two irons that serves as a catalytic center binds to the carboxyl O and the amino N of the substrate. Notably, we demonstrate that the AetD-catalyzed reaction is independent of the bromination of the substrate and also solved crystal structures of AetD in complex with 5-Br-L-Trp and L-Trp. Altogether, the present study reveals the substrate-binding pattern and validates the diiron cluster-comprising active center of AetD, which should provide important basis to support the mechanistic investigations into this class of nitrile synthase.

Impaired vascular β-adrenergic relaxation in spontaneously hypertensive rats: The differences between conduit and resistance arteries

It was suggested that impaired β-adrenergic relaxation in spontaneously hypertensive rats (SHR) might contribute to their high blood pressure (BP). Our study was focused on isoprenaline-induced dilatation of conduit femoral or resistance mesenteric arteries and on isoprenaline-induced BP reduction in SHR and Wistar-Kyoto rats (WKY). We confirmed decreased β-adrenergic relaxation of SHR femoral arteries due to the absence of its endothelium-independent component, whereas endothelium-dependent component of β-adrenergic smooth muscle relaxation was similar in both strains. Conversely, isoprenaline-induced relaxation of resistance mesenteric arteries was similar in both strains and this was true for endothelium-dependent and endothelium-independent components. We observed moderately reduced sensitivity of SHR mesenteric arteries to salmeterol (β2-adrenergic agonist) and this strain difference disappeared after endothelium removal. However, there was no difference in mesenteric arteries relaxation by dobutamine (β1-adrenergic agonist) which was independent of endothelium. The increasing isoprenaline doses elicited similar BP decrease in both rat strains, although BP sensitivity to isoprenaline was slightly decreased in SHR. The blockade of cyclooxygenase (indomethacin) and NO synthase (L-NAME) further reduced BP sensitivity to isoprenaline in SHR. On the other hand, salmeterol elicited similar BP decrease in both strains and the blockade of cyclooxygenase and NO synthase increased BP sensitivity to salmeterol in SHR as compared to WKY. In conclusion, attenuated β-adrenergic vasodilatation of conduit arteries of SHR but similar β-adrenergic relaxation of resistance mesenteric arteries from WKY and SHR and their similar BP response to β-adrenergic agonists do not support major role of altered β-adrenergic vasodilatation for high BP in genetic hypertension.

Acyl-CoA synthase ACSL4: an essential target in ferroptosis and fatty acid metabolism

ABSTRACT

Long-chain acyl-coenzyme A (CoA) synthase 4 (ACSL4) is an enzyme that esterifies CoA into specific polyunsaturated fatty acids, such as arachidonic acid and adrenic acid. Based on accumulated evidence, the ACSL4-catalyzed biosynthesis of arachidonoyl-CoA contributes to the execution of ferroptosis by triggering phospholipid peroxidation. Ferroptosis is a type of programmed cell death caused by iron-dependent peroxidation of lipids; ACSL4 and glutathione peroxidase 4 positively and negatively regulate ferroptosis, respectively. In addition, ACSL4 is an essential regulator of fatty acid (FA) metabolism. ACSL4 remodels the phospholipid composition of cell membranes, regulates steroidogenesis, and balances eicosanoid biosynthesis. In addition, ACSL4-mediated metabolic reprogramming and antitumor immunity have attracted much attention in cancer biology. Because it facilitates the cross-talk between ferroptosis and FA metabolism, ACSL4 is also a research hotspot in metabolic diseases and ischemia/reperfusion injuries. In this review, we focus on the structure, biological function, and unique role of ASCL4 in various human diseases. Finally, we propose that ACSL4 might be a potential therapeutic target.

Optically detected magnetic resonance and mutational analysis reveal significant differences in the photochemistry and structure of chlorophyll f synthase and photosystem II

In cyanobacteria that undergo far red light photoacclimation (FaRLiP), chlorophyll (Chl) f is produced by the ChlF synthase enzyme, probably by photo-oxidation of Chl a. The enzyme forms homodimeric complexes and the primary amino acid sequence of ChlF shows a high degree of homology with the D1 subunit of photosystem II (PSII). However, few details of the photochemistry of ChlF are known. The results of a mutational analysis and optically detected magnetic resonance (ODMR) data from ChlF are presented. Both sets of data show that there are significant differences in the photochemistry of ChlF and PSII. Mutation of residues that would disrupt the donor side primary electron transfer pathway in PSII do not inhibit the production of Chl f, while alteration of the putative ChlZ, P680 and QA binding sites rendered ChlF non-functional. Together with previously published transient EPR and flash photolysis data, the ODMR data show that in untreated ChlF samples, the triplet state of P680 formed by intersystem crossing is the primary species generated by light excitation. This is in contrast to PSII, in which 3P680 is only formed by charge recombination when the quinone acceptors are removed or chemically reduced. The triplet states of a carotenoid (3Car) and a small amount of 3Chl f are also observed by ODMR. The polarization pattern of 3Car is consistent with its formation by triplet energy transfer from ChlZ if the carotenoid molecule is rotated by 15° about its long axis compared to the orientation in PSII. It is proposed that the singlet oxygen formed by the interaction between molecular oxygen and 3P680 might be involved in the oxidation of Chl a to Chl f.

Inhibition of endogenous nitric oxide activity impairs the colonic sparing effect of rofecoxib, the cyclooxygenase-2 inhibitor and resveratrol, the preferential cyclooxygenase-1 inhibitor in the course of experimental colitis. Role of oxidative stress biomarkers and proinflammatory cytokines

The gut mucosal barrier plays a key role in the physiology of gastrointestinal (GI) tract, preventing under homeostatic conditions, the epithelial cells of the gastric mucosa from hydrochloric acid and intestinal mucosa from alkaline secretion, food toxins and pathogenic microbiota. Previous studies have documented that blockade of both isoforms of cyclooxygenase (COX): constitutive (COX-1) and inducible (COX-2), as well NO synthase in the stomach exacerbated the gastric damage induced by various ulcerogens, however, such as effects of non-selective and selective inhibition of COX-1, COX-2 and NOS enzymes on colonic damage have been little studied. The supplementation of NO by intragastric (i.g.) treatment with NO-releasing compound NO-aspirin (NO-ASA) or substrate for NO synthase L-arginine ameliorated the damage of upper GI-tract, but whether similar effect can be observed in colonic mucosa associated with the experimental colitis, and if above mentioned compounds can be effective in aggravation or protection of experimental colitis remains less recognized. In this study rats with experimental colitis induced by intrarectal administration of 2,4,6-trinitrobenzosulphonic acid (TNBS) were daily treated for 7 days with: 1) vehicle (i.g.), 2) ASA 40 mg/kg (i.g.), 3) rofecoxib 10 mg/kg (i.g.), 4) resveratrol 10 mg/kg (i.g.), 5) NO-ASA 40 mg/kg (i.g.), 6) L-arginine 200 mg/kg (i.g.) with or without of L-NNA 20 mg/kg (i.p.). The macroscopic and microscopic area of colonic damage was determined planimetrically, the colonic blood flow (CBF) was assessed by Laser flowmetry, and the oxidative stress biomarkers malondialdehyde and 4-hydroxynonenal (MDA+4-HNE), the antioxidative factors superoxide dismutase (SOD) and glutathione (GSH), as well as proinflammatory cytokines in the colonic mucosa (tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β)) were measured. We have documented that administration of TNBS produced gross and microscopic colonic damage and significantly decreased CBF (p<0.05). Treatment with ASA significantly increased the area of colonic damage (p<0.05), an effect accompanied by a significant decrease in the CBF, the significant increment of MDA+4-HNE, and the attenuation of the antioxidative properties in colonic mucosa, documented by a significant decrease of SOD activity and GSH concentration, and elevation of the colonic tissue levels of TNF-α and IL-1β comparing to control Veh-treated TNBS rats. Administration of rofecoxib or resveratrol also significantly increased the colonic damage and significantly decreased the CBF, causing an increase in MDA+4-HNE and mucosal content of TNF-α and IL-1α and a significant decrease of the SOD activity and GSH content (p<0.05), however, these changes were significantly less pronounced as compared with ASA. On the contrary, the treatment with NO-ASA, or L-arginine, significantly diminished the area of colonic lesions, the MDA+4-HNE concentration, attenuated the TNF-α and IL-1β levels, while increasing the CBF, SOD activity and GSH content (p<0.05). The concomitant treatment of L-NNA with rofecoxib or resveratrol reversed an increase in area of colonic damage and accompanying changes in CBF, colonic mucosa TNF-α and IL-1β levels, the MDA+4-HNE concentration, and SOD activity and GSH content comparing to those observed in TNBS rats treated with these COX-inhibitors alone (p<0.05). In contrast, co-treatment with L-NNA and NO-ASA or L-arginine failed to significantly affect the decrease of colonic lesions accompanied by the rise in CBF, the attenuation of MDA+4-HNE concentration, TNF-α and IL-1β levels, SOD activity and GSH content exerted by NO-ASA- or L-arginine treatment of the respective control TNBS-rats without L-NNA administration. These observations suggest that 1) the increase of NO availability either from NO-releasing donors such as NO-ASA or NO precursors such as L-arginine, can inhibit the inflammatory and microvasculature alterations, as well as increase in lipid peroxidation due to the enhanced efficacy of these compounds to increase the antioxidative properties of colonic mucosa, 2) unlike ASA which exacerbated the severity of colitis, the treatment with rofecoxib, the specific 'safer' COX-2 inhibitor or resveratrol, the polyphenolic compound known to act as the dual COX-1 and COX-2 inhibitor, can attenuate the colonic damage during course of TNBS colitis possibly via anti-inflammatory and antioxidative properties, and 3) the blockade of endogenous NO activity by L-NNA which also exacerbated the severity of mucosal damage in colitis, can abolish the sparing effect of rofecoxib and resveratrol indicating the NO bioavailability plays an important role in enhanced efficacy of both specific and dual COX inhibitors to ameliorate the experimental colitis.

Influence of a Nitric Oxide Synthase Inhibitor on the Anxiolytic, Stimulating, and Analgesic Effects of Long-Term Perinatal Caffeine Exposure in Rats

We studied the effect of inducible NO synthase (iNOS) inhibitor aminoguanidine on the behavioral effects of chronic perinatal caffeine exposure. Administration of caffeine in the prenatal and early postnatal periods led to the development of anxiolytic, stimulating, and analgesic effects. Administration of aminoguanidine attenuated the anxiolytic and stimulating effects and potentiated the analgesic effect of perinatal administration of caffeine. Chronic perinatal administration of caffeine leads to significant changes in the level of anxiety, motor activity, and pain sensitivity, and inhibition of iNOS has a pronounced multidirectional effect on these effects.

2-iminobiotin, a selective inhibitor of nitric oxide synthase, improves memory and learning in a rat model after four vessel occlusion, mimicking cardiac arrest

Survivors of out-of-hospital cardiac arrest (OHCA) experience between 30% and 50% cognitive deficits several years post-discharge. Especially spatial memory is affected due to ischemia-induced neuronal damage in the hippocampus. Aim of this study was to investigate the potential neuroprotective effect of 2-iminobiotin (2-IB), a biotin analogue, on memory and learning in a four-vessel occlusion model of global ischemia using the Water Maze test. Sprague-Dawley rats were randomly assigned to either sham operation (n = 6), vehicle treatment (n = 20), 1.1 (n = 15), 3.3 (n = 14), 10 (n = 14), or 30 mg/kg/dose 2-IB treatment (n = 15). Treatment was subcutaneously (s.c.) administered immediately upon reperfusion, at 12h, and at 24h after reperfusion. Memory function on day 32 was significantly preserved in all doses of 2-IB rats compared to vehicle, as was the learning curve in the 1.1, 3.3 and 30 mg/kg dose group. Adult rats treated s.c. with 3 gifts of 2-IB every 12 h in a dose range of 1.1-30 mg/kg/dose directly upon reperfusion showed significant improved memory and learning after four vessel occlusion compared to vehicle-treated rats. Since 2-IB has already shown to be safe in a phase 1 clinical trial in adult human volunteers, it is a suitable candidate for translation to a human phase 2 study after OHCA.

Transcriptomic, 16S ribosomal ribonucleic acid and network pharmacology analyses shed light on the anticoccidial mechanism of green tea polyphenols against Eimeria tenella infection in Wuliangshan black-boned chickens

BACKGROUND

Eimeria tenella is an obligate intracellular parasitic protozoan that invades the chicken cecum and causes coccidiosis, which induces acute lesions and weight loss. Elucidating the anticoccidial mechanism of action of green tea polyphenols could aid the development of anticoccidial drugs and resolve the problem of drug resistance in E. tenella.

METHODS

We constructed a model of E. tenella infection in Wuliangshan black-boned chickens, an indigenous breed of Yunnan Province, China, to study the efficacy of green tea polyphenols against the infection. Alterations in gene expression and in the microbial flora in the cecum were analyzed by ribonucleic acid (RNA) sequencing and 16S ribosomal RNA (rRNA) sequencing. Quantitative real-time polymerase chain reaction was used to verify the host gene expression data obtained by RNA sequencing. Network pharmacology and molecular docking were used to clarify the interactions between the component green tea polyphenols and the targeted proteins; potential anticoccidial herbs were also analyzed.

RESULTS

Treatment with the green tea polyphenols led to a reduction in the lesion score and weight loss of the chickens induced by E. tenella infection. The expression of matrix metalloproteinase 7 (MMP7), MMP1, nitric oxide synthase 2 and ephrin type-A receptor 2 was significantly altered in the E. tenella infection plus green tea polyphenol-treated group and in the E. tenella infection group compared with the control group; these genes were also predicted targets of tea polyphenols. Furthermore, the tea polyphenol (-)-epigallocatechin gallate acted on most of the targets, and the molecular docking analysis showed that it has good affinity with interferon induced with helicase C domain 1 protein. 16S ribosomal RNA sequencing showed that the green tea polyphenols had a regulatory effect on changes in the fecal microbiota induced by E. tenella infection. In total, 171 herbs were predicted to act on two or three targets in MMP7, MMP1, nitric oxide synthase 2 and ephrin type-A receptor 2.

CONCLUSIONS

Green tea polyphenols can directly or indirectly regulate host gene expression and alter the growth of microbiota. The results presented here shed light on the mechanism of action of green tea polyphenols against E. tenella infection in chickens, and have implications for the development of novel anticoccidial products.

Expanding the β-substitution reactions of serine synthase through mutagenesis of aromatic active site residues

The Gram-negative bacterium, Fusobacterium nucleatum, possesses a fold II type pyridoxal 5'-phosphate-dependent enzyme that catalyzes the reversible β-replacement of l-cysteine and l-serine, generating H2S and H2O, respectively. This enzyme, termed serine synthase (FN1055), contains an active site Asp232 that serves as a general base in the activation of a water molecule for nucleophilic attack of the ⍺-aminoacrylate intermediate. A network of hydrophobic residues surrounding Asp232 are key to catalysis as they increase the basicity of the side chain. However, these residues severely restrict the range of nucleophilic substrates that can react with the ⍺-aminoacrylate, making the enzyme an ineffective biocatalyst for noncanonical amino acid biosynthesis. Herein, we systematically substituted four aromatic active residues (Trp99, Phe125, Phe148 and Phe234) to an alanine to determine their catalytic importance in serine/cysteine synthase reactions and if their substitution could broaden the scope of nucleophiles that could react with the ⍺-aminoacrylate intermediate. All four single site mutants W99A, F125A, F148A, and F234A could form the ⍺-aminoacrylate intermediate upon reaction with either l-cysteine or l-serine; however, the rate constant associated with the elimination of the β-hydroxyl group from l-serine was 150 to 200-fold lower in the F125A and F148A variants. Substitution of Phe125 and Phe148, situated ∼3-4 Å from the general base, also abolished the serine synthase reaction due to their inability to activate a water molecule for nucleophilic attack of the ⍺-aminoacrylate. Overall, the mutational studies indicate that the clustering of aromatic residues disproportionately benefits the serine synthase reaction as they increase the binding affinity for l-cysteine, decrease the binding of the product, l-serine, and promote the activation of a water molecule. Notably, the aminoacrylate species present in F125A and F148A was able to react with thiophenol, signifying that serine synthase has biocatalytic potential in the synthesis of noncanonical amino acids.

The Batten disease gene product CLN5 is the lysosomal bis(monoacylglycero)phosphate synthase

Lysosomes critically rely on bis(monoacylglycero)phosphate (BMP) to stimulate lipid catabolism, cholesterol homeostasis, and lysosomal function. Alterations in BMP levels in monogenic and complex neurodegeneration suggest an essential function in human health. However, the site and mechanism responsible for BMP synthesis have been subject to debate for decades. Here, we report that the Batten disease gene product CLN5 is the elusive BMP synthase (BMPS). BMPS-deficient cells exhibited a massive accumulation of the BMP synthesis precursor lysophosphatidylglycerol (LPG), depletion of BMP species, and dysfunctional lipid metabolism. Mechanistically, we found that BMPS mediated synthesis through an energy-independent base exchange reaction between two LPG molecules with increased activity on BMP-laden vesicles. Our study elucidates BMP biosynthesis and reveals an anabolic function of late endosomes/lysosomes.

Hepatic FASN deficiency differentially affects nonalcoholic fatty liver disease and diabetes in mouse obesity models

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor-deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

Coordinated peptidoglycan synthases and hydrolases stabilize the bacterial cell wall

Peptidoglycan (PG) defines cell shape and protects bacteria against osmotic stress. The growth and integrity of PG require coordinated actions between synthases that insert new PG strands and hydrolases that generate openings to allow the insertion. However, the mechanisms of their coordination remain elusive. Moenomycin that inhibits a family of PG synthases known as Class-A penicillin-binding proteins (aPBPs), collapses rod shape despite aPBPs being non-essential for rod-like morphology in the bacterium Myxococcus xanthus. Here, we demonstrate that inhibited PBP1a2, an aPBP, accelerates the degradation of cell poles by DacB, a hydrolytic PG peptidase. Moenomycin promotes the binding between DacB and PG and thus reduces the mobility of DacB through PBP1a2. Conversely, DacB also regulates the distribution and dynamics of aPBPs. Our findings clarify the action of moenomycin and suggest that disrupting the coordination between PG synthases and hydrolases could be more lethal than eliminating individual enzymes.

Nitric oxide synthase inhibitors as potential therapeutic agents for gliomas: A systematic review

INTRODUCTION

Gliomas represent the most prevalent form of brain tumors, among which glioblastomas are the most malignant subtype. Despite advances in comprehending their biology and treatment strategies, median survival remains disappointingly low. Inflammatory processes involving nitric oxide (NO), critically contribute to glioma formation. The inducible isoform of NO synthase (iNOS) is highly overexpressed in gliomas and has been linked to resistance against temozolomide (TMZ) treatment, neoplastic transformation, and modulation of immune response. While both in vitro and in vivo studies showed the potential of iNOS inhibitors as effective treatments for gliomas, no clinical trials on gliomas have been published. This review aims to summarize the available evidence regarding iNOS as a target for glioma treatment, focusing on clinically relevant data.

METHODS

Following PRISMA guidelines, we conducted a systematic review by searching PubMed/Medline, and Embase databases in May 2023. We included studies that investigated the impact of NOS inhibitors on glioma cells using L-NMMA, CM544, PBN, 1400W or l-NAME either alone or combined with TMZ. We extracted data on the NOS inhibitor used, subtype, study setting, animal model or cell lines employed, obtained results, and safety profile. Our inclusion criteria encompassed original articles in English or Spanish, studies with an untreated control group, and a primary outcome focused on the biological effects on glioma cells.

RESULTS

Out of 871 articles screened from the aforementioned databases, 37 reports were assessed for eligibility. After excluding studies that did not utilize glioma cells or address the designated outcome, 11 original articles satisfied the inclusion and exclusion criteria. Although no NOS inhibitor has been tested in a published clinical trial, three inhibitors have been evaluated using in vivo models of intracranial gliomas. l-NAME, 1400W, and CM544 were tested in vitro. Co-administration of l-NAME, or CM544 with TMZ showed superior results in vitro compared to individual agent testing.

CONCLUSION

Glioblastomas remain a challenging therapeutic target. iNOS inhibitors exhibit substantial potential as treatment options for oncologic lesions, and they have demonstrated a safe toxicity profile in humans for other pathological conditions. Research endeavors should be focused on investigating their potential effects on brain tumors.

Functional diversity of diterpene synthases in Aconitum plants

Members of the Aconitum genus within the Ranunculaceae family are known to accumulate a broad array of medicinal and toxic diterpenoid alkaloids (DAs). Historically, ent-copalyl diphosphate (ent-CPP) was considered the sole precursor in DAs biosynthesis. However, the recent discovery of ent-8,13-CPP synthase in A. gymnandrum Maxim., which participates in ent-atiserene biosynthesis, raises the question of whether this gene is conserved throughout the Aconitum genus. In this study, RNA sequencing and PacBio Iso-sequencing were employed to identify diterpene synthases (diTPSs) in four additional Aconitum species with distinct DA compositions. In vitro and in vivo analyses functionally characterized a diverse array of 10 class II and 9 class I diTPSs. In addition to the identification of seven class II diTPSs as ent-CPP synthases, three other synthases generating ent-8,13-CPP, 8,13-CPP, and 8α-hydroxy-CPP were also discovered. Four class I kaurene synthases-like (KSLs) were observed to react with ent-CPP to yield ent-kaurene. Three KSLs not only reacted with ent-CPP but also ent-8,13-CPP to produce ent-atiserene. AsiKSL2-1 was found to react with 8α-hydroxy-CPP to produce Z-abienol and AsiKSL2-2 exhibited no activity with any of the four intermediates. This research delineates the known diterpene biosynthesis pathways in six Aconitum species and explores the highly divergent diterpene synthases within the genus, which are consistent with their phylogeny and may be responsible for the differential distribution of diterpenoid alkaloids in root and aerial parts. These findings contribute valuable insights into the diversification of diterpene biosynthesis and establish a solid foundation for future investigation into DA biosynthetic pathways in Aconitum.

Identification and characterization of novel sesquiterpene synthases TPS9 and TPS12 from Aquilaria sinensis

Sesquiterpenes are characteristic components and important quality criterions for agarwood. Although sesquiterpenes are well-known to be biosynthesized by sesquiterpene synthases (TPSs), to date, only a few TPS genes involved in agarwood formation have been reported. Here, two new TPS genes, namely, TPS9 and TPS12, were isolated from Aquilaria sinensis (Lour.) Gilg, and their functions were examined in Escherichia coli BL21(DE3), with farnesyl pyrophosphate (FPP) and geranyl pyrophosphate (GPP) as the substrate of the corresponding enzyme activities. They were both identified as a multiproduct enzymes. After incubation with FPP, TPS9 liberated β-farnesene and cis-sesquisabinene hydrate as main products, with cedrol and another unidentified sesquiterpene as minor products. TPS12 catalyzes the formation of β-farnesene, nerolidol, γ-eudesmol, and hinesol. After incubation with GPP, TPS9 generated citronellol and geraniol as main products, with seven minor products. TPS12 converted GPP into four monoterpenes, with citral as the main product, and three minor products. Both TPS9 and TPS12 showed much higher expression in the two major tissues emitting floral volatiles: flowers and agarwood. Further, RT-PCR analysis showed TPS9 and TPS12 are typical genes mainly expressed during later stages of stress response, which is better known than that of chromone derivatives. This study will advance our understanding of agarwood formation and provide a solid theoretical foundation for clarifying its mechanism in A. sinensis.

The ATP Synthase Subunits FfATPh, FfATP5, and FfATPb Regulate the Development, Pathogenicity, and Fungicide Sensitivity of Fusarium fujikuroi

ATP synthase catalyzes the synthesis of ATP by consuming the proton electrochemical gradient, which is essential for maintaining the life activity of organisms. The peripheral stalk belongs to ATP synthase and plays an important supporting role in the structure of ATP synthase, but their regulation in filamentous fungi are not yet known. Here, we characterized the subunits of the peripheral stalk, FfATPh, FfATP5, and FfATPb, and explored their functions on development and pathogenicity of Fusarium Fujikuroi. The FfATPh, FfATP5, and FfATPb deletion mutations (∆FfATPh, ∆FfATP5, and ∆FfATPb) presented deficiencies in vegetative growth, sporulation, and pathogenicity. The sensitivity of ∆FfATPh, ∆FfATP5, and ∆FfATPb to fludioxonil, phenamacril, pyraclostrobine, and fluazinam decreased. In addition, ∆FfATPh exhibited decreased sensitivity to ionic stress and osmotic stress, and ∆FfATPb and ∆FfATP5 were more sensitive to oxidative stress. FfATPh, FfATP5, and FfATPb were located on the mitochondria, and ∆FfATPh, ∆FfATPb, and ∆FfATP5 disrupted mitochondrial location. Furthermore, we demonstrated the interaction among FfATPh, FfATP5, and FfATPb by Bimolecular Fluorescent Complimentary (BiFC) analysis. In conclusion, FfATPh, FfATP5, and FfATPb participated in regulating development, pathogenicity, and sensitivity to fungicides and stress factors in F. fujikuroi.

Promoter characterization of a citrus linalool synthase gene mediating interspecific variation in resistance to a bacterial pathogen

BACKGROUND

Terpenoids play essential roles in plant defense against biotic stresses. In Citrus species, the monoterpene linalool mediates resistance against citrus canker disease caused by the gram-negative bacteria Xanthomonas citri subsp. citri (Xcc). Previous work had associated linalool contents with resistance; here we characterize transcriptional responses of linalool synthase genes.

RESULTS

Leaf linalool contents are highly variable among different Citrus species. "Dongfang" tangerine (Citrus reticulata), a species with high linalool levels was more resistant to Xcc than "Shatian" pummelo (C. grandis) which accumulates only small amounts of linalool. The coding sequences of the major leaf-expressed linalool synthase gene (STS4) are highly conserved, while transcript levels differ between the two Citrus species. To understand this apparent differential transcription, we isolated the promoters of STS4 from the two species, fused them to a GUS reporter and expressed them in Arabidopsis. This reporter system revealed that the two promoters have different constitutive activities, mainly in trichomes. Interestingly, both linalool contents and STS4 transcript levels are insensitive to Xcc infestation in citrus plants, but in these transgenic Arabidopsis plants, the promoters are activated by challenge of a bacterial pathogen Pseudomonas syringae, as well as wounding and external jasmonic acid treatment.

CONCLUSIONS

Our study reveals variation in linalool and resistance to Xcc in citrus plants, which may be mediated by different promoter activities of a terpene synthase gene in different Citrus species.

Genome-Wide Identification and Expression Analysis of ANS Family in Strawberry Fruits at Different Coloring Stages

To elucidate the structural characteristics, phylogeny and biological function of anthocyanin synthase (ANS) and its role in anthocyanin synthesis, members of the strawberry ANS gene family were obtained by whole genome retrieval, and their bioinformatic analysis and expression analysis at different developmental stages of fruit were performed. The results showed that the strawberry ANS family consisted of 141 members distributed on 7 chromosomes and could be divided into 4 subfamilies. Secondary structure prediction showed that the members of this family were mainly composed of random curls and α-helices, and were mainly located in chloroplasts, cytoplasm, nuclei and cytoskeletons. The promoter region of the FvANS gene family contains light-responsive elements, abiotic stress responsive elements and hormone responsive elements, etc. Intraspecific collinearity analysis revealed 10 pairs of FvANS genes, and interspecific collinearity analysis revealed more relationships between strawberries and apples, grapes and Arabidopsis, but fewer between strawberries and rice. Chip data analysis showed that FvANS15, FvANS41, FvANS47, FvANS48, FvANS49, FvANS67, FvANS114 and FvANS132 were higher in seed coat tissues and endosperm. FvANS16, FvANS85, FvANS90 and FvANS102 were higher in internal and fleshy tissues. Quantitative real-time PCR (qRT-PCR) showed that the ANS gene was expressed throughout the fruit coloring process. The expression levels of most genes were highest in the 50% coloring stage (S3), such as FvANS16, FvANS19, FvANS31, FvANS43, FvANS73, FvANS78 and FvANS91. The expression levels of FvANS52 were the highest in the green fruit stage (S1), and FvANS39 and FvANS109 were the highest in the 20% coloring stage (S2). These results indicate that different members of the FvANS gene family play a role in different pigmentation stages, with most genes playing a role in the expression level of the rapid accumulation of fruit coloring. This study lays a foundation for further study on the function of ANS gene family.

Acute nitric oxide synthase inhibition induces greater increases in blood pressure in female versus male Wistar Kyoto rats

Nitric oxide (NO) contributes to blood pressure (BP) regulation via its vasodilatory and anti-inflammatory properties. We and others previously reported sex differences in BP in normotensive and hypertensive rat models where females have lower BP than age-matched males. As females are known to have greater NO bioavailability than age-matched males, the current study was designed to test the hypothesis that anesthetized female normotensive Wistar Kyoto rats (WKY) are more responsive to acute NOS inhibition-induced increases in BP compared to male WKY. Twelve-week-old male and female WKY were randomized to infusion of the nonspecific NOS inhibitor NG -nitro-L-arginine methyl ester (L-NAME, 1 mg/kg/min) or selective NOS1 inhibition with vinyl-L-NIO (VNIO, 0.5 mg/kg/min) for 60 min. Mean arterial BP, glomerular filtration rate (GFR), urine volume, and electrolyte excretion were assessed before, and during L-NAME or VNIO infusion. L-NAME and VNIO significantly increased BP in both sexes; however, the increase in BP with L-NAME infusion was greater in females versus males compared to baseline BP values. Acute infusion of neither L-NAME nor VNIO for 60 min altered GFR in either sex. However, urine volume, sodium, chloride and potassium excretion levels increased comparably in male and female WKY with L-NAME and VNIO infusion. Our findings suggest sex differences in BP responses to acute non-isoform-specific NOS inhibition in WKY, with females being more responsive to L-NAME-induced elevations in BP relative to male WKY. However, sex differences in the BP response did not coincide with sex differences in renal hemodynamic responses to acute NOS inhibition.

Molecular Mechanisms of Migraine: Nitric Oxide Synthase and Neuropeptides

Migraine is a common condition with disabling attacks that burdens people in the prime of their working lives. Despite years of research into migraine pathophysiology and therapeutics, much remains to be learned about the mechanisms at play in this complex neurovascular condition. Additionally, there remains a relative paucity of specific and targeted therapies available. Many sufferers remain underserved by currently available broad action preventive strategies, which are also complicated by poor tolerance and adverse effects. The development of preclinical migraine models in the laboratory, and the advances in human experimental migraine provocation, have led to the identification of key molecules likely involved in the molecular circuity of migraine, and have provided novel therapeutic targets. Importantly, the identification that vasoconstriction is neither necessary nor required for headache abortion has changed the landscape of migraine treatment and has broadened the therapy targets for patients with vascular risk factors or vascular disease. These targets include nitric oxide synthase (NOS) and several neuropeptides that are involved in migraine. The ability of NO donors and infusion of some of these peptides into humans to trigger typical migraine-like attacks has supported the development of targeted therapies against these molecules. Some of these, such as those targeting calcitonin gene-related peptide (CGRP), have already reached clinical practice and are displaying a positive outcome in migraineurs for the better by offering targeted efficacy without significant adverse effects. Others, such as those targeting pituitary adenylate cyclase activating polypeptide (PACAP), are showing promise and are likely to enter phase 3 clinical trials in the near future. Understanding these nitrergic and peptidergic mechanisms in migraine and their interactions is likely to lead to further therapeutic strategies for migraine in the future.

Successful Use of Methylene Blue in Catecholamine-Resistant Septic Shock: A Case Report and Short Literature Review

Despite efforts to improve treatment outcomes, mortality in septic shock remains high. In some patients, despite the use of several adrenergic drugs, features of refractory vasoplegic shock with progressive multiorgan failure are observed. We present a case report of the successful reversal of vasoplegic shock following the use of methylene blue, a selective inhibitor of the inducible form of nitric oxide synthase, which prevents vasodilation in response to inflammatory cytokines. We also briefly review the literature.

Production of Diketopiperazine Derivatives by Pathway Engineering with Different Cyclodipeptide Synthases from Various Streptomyces Strains

Cyclodipeptides from fungi and bacteria are often modified by different tailoring enzymes. They display various biological and pharmacological activities, and some derivatives are used as drugs. In a previous study, we elucidated the function of the silent guatrypmethine gene cluster from Streptomyces cinnamoneus containing a cyclodipeptide synthase (CDPS) core gene gtmA and four genes gtmB-gtmE for tailoring enzymes. The latter are used in this study for the design of modified cyclodipeptides by genetic engineering. Addition of six different cyclodipeptides to the Streptomyces albus transformant harboring gtmB-gtmE led to the detection of different pathway products. Coexpression of five CDPS genes from four Streptomyces strains with gtmB-gtmE resulted in the formation of diketopiperazine derivatives, differing in their modification stages. Our results demonstrate the potential of rational gene combination to increase structural diversity.

Involvement of the Restoration of Cerebral Blood Flow and Maintenance of eNOS Expression in the Prophylactic Protective Effect of the Novel Ferulic Acid Derivative FAD012 against Ischemia/Reperfusion Injuries in Rats

Tissue plasminogen activator, aiming to restore cerebral blood flow (CBF), has been used for acute ischemic strokes in clinics; however, its narrow therapeutic time window remains a serious concern. To develop novel prophylactic drugs to alleviate cerebral ischemia/reperfusion injuries, ferulic acid derivative 012 (FAD012) was synthesized and showed comparable antioxidant properties to ferulic acid (FA) and probably possesses the potent ability to cross the blood-brain barrier. A more potent cytoprotective effect of FAD012 against H2O2-induced cytotoxicity in PC12 cells was also observed. In vivo toxicity was not observed in rats given a long-term oral administration of FAD012, indicating its good tolerability. A one-week-course oral administration of FAD012 significantly alleviated middle cerebral artery occlusion (MCAO)-induced cerebral ischemia/reperfusion injuries in rats, accompanied by the restoration of CBF and endothelial nitrogen oxide synthetase (eNOS) expression. Treatment with FAD012 significantly restored the cell viability and eNOS expression damaged by H2O2, used to mimic MCAO-triggered oxidative stress, in rat brain microvascular endothelial cells. Our findings suggested that FAD012 protected the viability of vascular endothelium and maintained eNOS expression, ultimately contributing to the restoration of CBF, and may provide a rationale for the development of FAD012 into an effective prophylactic drug for patients at high risk of stroke.

Autoregulation and Autoinhibition of the Main NO Synthase Isoforms (Brief Review)

Nitric oxide (II) (NO) is the most important mediator of a wide range of physiological and pathophysiological processes. It is synthesized by NO synthases (NOSs), which have three main isoforms differing from each other in terms of activation and inhibition features, levels of NO production, subcellular localization, etc. At the same time, all isoforms are structurally very similar, and these differences are determined by NOS autoregulatory elements. The article presents an analysis of the autoregulatory and autoinhibitory mechanisms of the NOS reductase domain that determine differences in the productivity of isoforms, as well as their dependence on the concentration of Ca2+ ions. The main regulatory elements in NOS that modulate the electron transfer from flavin to heme include calmodulin (CaM), an autoinhibitory insert (AI), and the C-terminal tail (C-tail). Hydrophobic interactions of CaM with the surface of the NOS oxidase domain are assumed to facilitate electron transfer from flavin mononucleotide (FMN). CaM binding causes a change in the inter-domain distances, a shift of AI and the C-tail, and, as a result, a decrease in their inhibitory effect. CaM also shifts the conformational equilibrium of the reductase domain towards more open conformations, reduces the lifetime of conformations, their stereometric distribution, and accelerates the flow of electrons through the reductase domain. The AI element, apparently, induces a conformational change that hinders electron transfer within the reductase domain, similar to the hinge domain in cytochrome P450. Together with CaM, the C-tail regulates the electron flow between flavins, the distance and relative orientation of isoalloxane rings, and also modulates the electron flow from FMN to the terminal acceptor. Together with the C-tail, AI also predetermines the dependence of neuronal and endothelial forms of NOS on the concentration of Ca2+ ions, and the C-tail length affects differences in the productivity of NO synthesis. The inhibitory effect of the C-tail is likely to be reduced by CaM binding due to the C-tail shift due to the electrostatic repulsive forces of the negatively charged phosphate and aspartate residues. The autoregulatory elements of NOS require further study, since the mechanisms of their interaction are complex and multidirectional, and hence provide a wide range of characteristics of the observed isoforms.

FOF1-ATP synthase molecular motor biosensor for miRNA detection of colon cancer

AIMS

To establish a F_OF1-ATP synthase molecular motor biosensor to accurately identify colon cancer miRNAs.

MAIN METHODS

The F_OF1-ATP synthase molecular motor is extracted by fragmentation-centrifugation and connected to the colon cancer-specific miR-17 capture probe in the manner of the ε subunit-biotin-streptavidin-biotin system. Signal probes are designed for dual-signal characterization to increase detection accuracy. The F_OF1-ATPase rotation rate decreases when the signaling and capture probes are combined with the target miRNA, resulting in a decrease in ATP synthesis. miR-17 concentrations are determined by changes in ATP-mediated chemiluminescence intensity and signal probe-mediated OD_450nm.

KEY FINDINGS

The chemiluminescence intensity and OD_450nm show a good linear relationship with the miR-17 concentration in the range of 5 to 200 nmol L^-1 (R² = 0.9985, 0.9989). The colon cancer mouse model is established for the blood samples, and miR-17 in serum and RNA extracts is quantitatively determined using the constructed sensor.

SIGNIFICANCE

The results are consistent with colon cancer progression, and the low concentration of miR-17 detecting accuracy is comparable to the PCR assay. In conclusion, the developed method is a direct, rapid, and promising method for miRNA detection of colon cancer.

Berberine hydrochloride inhibits migration ability via increasing inducible NO synthase and peroxynitrite in HTR-8/SVneo cells

ETHNOPHARMACOLOGICAL RELEVANCE

Inadequate trophoblasts migration and invasion is considered as an initial event resulting in preeclampsia, which is closely related to oxidative stress. Berberine hydrochloride (BBR), extracted from the traditional medicinal plant Coptis chinensis Franch., exerts a diversity of pharmacological effects, and the crude drug has been widely taken by most Chinese women to treat nausea and vomit during pregnancy. But there is no research regarding its effects on trophoblast cell function.

AIM OF THE STUDY

This study aimed to investigate the effect of BBR on human-trophoblast-derived cell line (HTR-8/SVneo) migration ability and its mechanism.

MATERIALS AND METHODS

Cell viability was detected by CCK-8 assay. The effect of BBR on cells migration function was examined by scratch wound healing assay and transwell migration assay. Intracellular nitric oxide (NO), superoxide (O₂^-) and peroxynitrite (ONOO^-) levels were measured by flow cytometry. The expression levels of inducible NO synthase (iNOS), eNOS, p-eNOS, MnSOD, CuZnSOD, Rac1, NOX1, TLR4, nuclear factor-κB (NF-κB), p-NFκB, pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in cells were analyzed by Western blotting. Uric acid sodium salt (UA), the scavenger of ONOO^-, PEG-SOD (a specific superoxide scavenger), L-NAME (a NOS inhibitor) and antioxidants (Vit E and DFO) were further used to characterize the pathway of BBR action.

RESULTS

5 μM BBR decreased both the migration distance and the number of migrated cells without affecting cells viability in HTR-8/SVneo cells after 24 h treatment. BBR could increase the level of NO in HTR-8/SVneo cells, and the over-production of NO might be attributable to iNOS, but not eNOS. BBR could increase intracellular O₂^- levels, and the over-production of O₂^- is closely related with Rac1 in HTR-8/SVneo cells. The excessive production of NO and O₂^- further react to form ONOO^-, and the increased ONOO^- level induced by BBR was blunted by UA. Moreover, UA improved the impaired migration function caused by BBR in HTR-8/SVneo cells. The depressed migration function stimulated by BBR in HTR-8/SVneo cells was diminished by PEG-SOD and L-NAME. Furthermore, BBR increased the expression of IL-6 in HTR-8/SVneo cells, and antioxidants (Vit E and DFO) could decrease the expression of IL-6 and iNOS induced by BBR.

CONCLUSIONS

BBR inhibits the cell migration ability through increasing inducible NO synthase and peroxynitrite in HTR-8/SVneo cells, indicating that BBR and traditional Chinese medicines containing a high proportion of BBR should be used with caution in pregnant women.

Nitric oxide mediated hypoxia dynamics in COVID-19

Several COVID-19 patients frequently experience with happy hypoxia. Sometimes, the level of nitric oxide (NO) in COVID-19 patients was found to be greater than in non-COVID-19 hypoxemics and most of the cases lower. Induced or inhaled NO has a long history of usage as a therapy for hypoxemia. Excessive production of ROS and oxidative stress lower the NO level and stimulates mitochondrial malfunction is the primary cause of hypoxia-mediated mortality in COVID-19. Higher level of NO in mitochondria also the cause of dysfunction, because, excess NO can also diffuse quickly into mitochondria or through mitochondrial nitric oxide synthase (NOS). A precise dose of NO may increase oxygenation while also acting as an effective inhibitor of cytokine storm. NOS inhibitors may be used in conjunction with iNO therapy to compensate for the patient's optimal NO level. NO play a key role in COVID-19 happy hypoxia and a crucial component in the COVID-19 pathogenesis that demands a reliable and easily accessible biomarker to monitor.

Activating P2Y1 receptors improves function in arteries with repressed autophagy

AIM

The importance of endothelial cell (EC) autophagy to vascular homeostasis in the context of health and disease is evolving. Earlier, we reported that intact EC autophagy is requisite to maintain shear-stress-induced nitric oxide (NO) generation via glycolysis-dependent purinergic signalling to endothelial NO synthase (eNOS). Here, we illustrate the translational and functional significance of these findings.

METHODS AND RESULTS

First, we assessed translational relevance using older male humans and mice that exhibit blunted EC autophagy and impaired arterial function vs. adult controls. Active hyperaemia evoked by rhythmic handgrip exercise-elevated radial artery shear-rate similarly from baseline in adult and older subjects for 60 min. Compared with baseline, indexes of autophagy initiation, p-eNOSS1177 activation, and NO generation, occurred in radial artery ECs obtained from adult but not older volunteers. Regarding mice, indexes of autophagy and p-eNOSS1177 activation were robust in ECs from adult but not older animals that completed 60-min treadmill-running. Furthermore, 20 dyne • cm2 laminar shear stress × 45-min increased autophagic flux, glycolysis, ATP production, and p-eNOSS1177 in primary arterial ECs obtained from adult but not older mice. Concerning functional relevance, we next questioned whether the inability to initiate EC autophagy, glycolysis, and p-eNOSS1177in vitro precipitates arterial dysfunction ex vivo. Compromised intraluminal flow-mediated vasodilation displayed by arteries from older vs. adult mice was recapitulated in vessels from adult mice by (i) NO synthase inhibition; (ii) acute autophagy impairment using 3-methyladenine (3-MA); (iii) EC Atg3 depletion (iecAtg3KO mice); (iv) purinergic 2Y1-receptor (P2Y1-R) blockade; and (v) germline depletion of P2Y1-Rs. Importantly, P2Y1-R activation using 2-methylthio-ADP (2-Me-ADP) improved vasodilatory capacity in arteries from (i) adult mice treated with 3-MA; (ii) adult iecAtg3KO mice; and (iii) older animals with repressed EC autophagy.

CONCLUSIONS

Arterial dysfunction concurrent with pharmacological, genetic, and age-associated EC autophagy compromise is improved by activating P2Y1-Rs.

Nitric oxide and salt resistance in Dahl rats: no role of inducible NO synthase

Inducible NO synthase (NOS II) was proposed to play an important role in salt resistance of Dahl salt-resistant (SR/Jr) rats. Its chronic inhibition by specific inhibitors was accompanied by blood pressure (BP) elevation in animals subjected to high salt intake. The aim of our study was to evaluate 1) whether such inhibitors affect BP and/or its particular components (sympathetic tone and NO-dependent vasodilation) only under the conditions of high salt intake, and 2) whether similar BP effects are elicited after systemic or intracerebroventricular (icv) application of these inhibitors. Wistar rats fed Altromin diet (0.45 % NaCl) and SR/Jr rats fed either a low-salt (LS, 0.3 % NaCl) or a high-salt (HS, 4 % NaCl) diet were studied. Aminoguanidine (AMG) and 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) were used as NOS II inhibitors. BP and its responses to acute blockade of renin-angiotensin system (captopril), sympathetic nervous system (pentolinium) and NO synthase (L-NAME) were measured in conscious cannulated rats. There were no significant changes of BP or its components in either Wistar rats or SR/Jr rats subjected to chronic inhibition of NOS II by peroral aminoguanidine administration (50 mg/kg/day for 4 weeks). This was true for SR/Jr rats fed either LS or HS diets. Furthermore, we have studied BP effects of chronic icv administration of both NOS II inhibitors in SR/Jr rats fed HS diet, but we failed to find any BP changes elicited by such treatment. In conclusion, inducible NO synthase does not participate in the resistance of SR/Jr rats to hypertensive effects of excess salt intake.