Electrostatic Repulsion Hydrophilic Interaction Liquid Chromatography (ERLIC) for the Quantitative Analysis of Polyamines

Highly polar low molecular weight organic molecules are still very challenging to analyze by liquid chromatography. Yet, with the steadily increasing application of metabolomics and similar approaches in chemical analysis, separating polar compounds might be even more important. However, almost all established liquid chromatography techniques (i.e., normal and reversed phase, hydrophilic interaction liquid chromatography (HILIC), ion chromatography) struggle with either carry-over, low sensitivity, or a lack of retention. For improving these shortcomings, electrostatic repulsion hydrophilic interaction chromatography (ERLIC) might be an alternative. By combining a HILIC mobile phase, that is highly organic with a low water content, and an ion exchange column, a distinct layer system develops. When the analyte's charge is of the same direction as the stationary phase, retention and elution are determined by two antagonistic forces: electrostatic repulsion and hydrophilicity. One prominent group of challenging polar analytes are the polyamines cadaverine, putrescine, spermidine, and spermine. Carrying charges from +2 to +4 at physiological pH, these compounds are essential cell constituents and found in all living organisms. However, they are still notoriously challenging to analyze via the established liquid chromatography methods. In the present work, an ERLIC tandem mass spectrometry method has been exemplarily developed, optimized, and validated for the quantitative determination of cadaverine, putrescine, spermidine, and spermine. This method enables symmetrical peak shapes and good separation of analytes with different charges while simultaneously selectively detecting the co-eluting diamines by MS/MS. Furthermore, high linearity (R > 0.998) and sensitivity (LODs ≤ 2 ng/mL) have been proven. Thus, ERLIC may be interesting for both targeted and untargeted analysis approaches of highly charged low molecular weight organic molecules.

Age-specific Metabolomic profiles in children with food allergy

BACKGROUND

Food allergy (FA) in young children is often associated with eczema, frequently directed to egg/cow milk allergens and has a higher chance of resolution, while FA that persists in older children has less chance of resolution and is less clearly associated with atopy.

METHODS

Children with FA (n = 62) and healthy controls (n = 28) were categorized into "younger" (≤5 years) and "older" (>5 years). Mass spectrometry-based untargeted metabolomic profiling as wells as cytokine profiling were performed on plasma samples in FA children in each age group.

RESULTS

Younger FA children manifested unique alterations in bile acids, polyamine metabolites and chemokines associated with Th2 responses, while older FA children displayed pronounced changes in long chain fatty acids, acylcarnitines and proinflammatory cytokines.

CONCLUSIONS

FA children of different ages manifest unique metabolic changes which may reflect at least in part pathogenic mechanisms and environmental influences operative at different time points in the disease course.

Loss-of-function variant in spermidine/spermine N1-acetyl transferase like 1 (SATL1) gene as an underlying cause of autism spectrum disorder

Autism spectrum disorder (ASD) is a complicated, lifelong neurodevelopmental disorder affecting verbal and non-verbal communication and social interactions. ASD signs and symptoms appear early in development before the age of 3 years. It is unlikely for a person to acquire autism after a period of normal development. However, we encountered an 8-year-old child who developed ASD later in life although his developmental milestones were normal at the beginning of life. Sequencing the complete coding part of the genome identified a hemizygous nonsense mutation (NM_001367857.2):c.1803C>G; (p.Tyr601Ter) in the gene (SATL1) encoding spermidine/spermine N1-acetyl transferase like 1. Screening an ASD cohort of 28 isolated patients for the SATL1 gene identified another patient with the same variant. Although SATL1 mutations have not been associated with any human diseases, our data suggests that a mutation in SATL1 is the underlying cause of ASD in our cases. In mammals, mutations in spermine synthase (SMS), an enzyme needed for the synthesis of spermidine polyamine, have been reported in a syndromic form of the X-linked mental retardation. Moreover, SATL1 gene expression studies showed a relatively higher expression of SATL1 transcripts in ASD related parts of the brain including the cerebellum, amygdala and frontal cortex. Additionally, spermidine has been characterized in the context of learning and memory and supplementations with spermidine increase neuroprotective effects and decrease age-induced memory impairment. Furthermore, spermidine biosynthesis is required for spontaneous axonal regeneration and prevents α-synuclein neurotoxicity in invertebrate models. Thus, we report, for the first time, that a mutation in the SATL1 gene could be a contributing factor in the development of autistic symptoms in our patients.

Functional divergence of two arginine decarboxylase genes in tropane alkaloid biosynthesis and root growth in Atropa belladonna

Putrescine, produced via the arginine decarboxylase (ADC)/ornithine decarboxylase (ODC)-mediated pathway, is an initial precursor for polyamines metabolism and the root-specific biosynthesis of medicinal tropane alkaloids (TAs). These alkaloids are widely used as muscarinic acetylcholine antagonists in clinics. Although the functions of ODC in biosynthesis of polyamines and TAs have been well investigated, the role of ADC is still poorly understood. In this study, enzyme inhibitor treatment showed that ADC was involved in the biosynthesis of putrescine-derived metabolites and root growth in Atropa belladonna. Further analysis found that there were six ADC unigenes in the A. belladonna transcriptome, with two of them, AbADC1 and AbADC2, exhibiting high expression in the roots. To investigate their roles in TAs/polyamines metabolism and root growth, RNA interference (RNAi) was used to suppress either AbADC1 or AbADC2 expression in A. belladonna hairy roots. Suppression of the AbADC1 expression resulted in a significant reduction in the putrescine content and hairy root biomass. However, it had no noticeable effect on the levels of N-methylputrescine and the TAs hyoscyamine, anisodamine, and scopolamine. On the other hand, suppression of AbADC2 expression markedly reduced the levels of putrescine, N-methylputrescine, and TAs, but had no significant effect on hairy root biomass. According to β-glucuronidase (GUS) staining assays, AbADC1 was mainly expressed in the root elongation and division region while AbADC2 was mainly expressed in the cylinder of the root maturation region. These differences in expression led to functional divergence, with AbADC1 primarily regulating root growth and AbADC2 contributing to TA biosynthesis.

Selenium treatment alters the accumulation of osmolytes in arsenic-stressed rice (Oryza sativa L.)

Arsenic (As), one of the major pollutants in the soil, is an important environmental concern as its consumption can cause adverse health symptoms in living organisms. Its contamination of rice grown over As-contaminated areas is a serious concern in South Asian countries. Selenium (Se) has been reported to influence various osmolytes under metal stress in plants. The present study reports the role of Se in mitigating As stress in rice by modulating osmolyte metabolism. Rice plants grown in As-amended soil (2.5-10 mg kg-1) in pots were treated with sodium selenate (0.5-1.0 mg Se kg-1 soil) in glass house conditions and leaf samples were collected at 60 and 90 days after sowing (DAS). As-treated rice leaves displayed a reduction in relative water content (RWC) and dry weight than control with a maximum reduction of 1.68- and 2.47-fold in RWC and 1.95- and 1.69-fold in dry weight in As10 treatment at 60 and 90 DAS, respectively. Free amino acids (1.38-2.26-fold), proline (3.88-3.93-fold), glycine betaine (GB) (1.27-1.72-fold), choline (1.67-3.1-fold), total soluble sugars (1.29-1.61-fold), and reducing sugars (1.67-2.19-fold) increased in As-treated rice leaves as compared to control at both stages. As stress increased the γ-aminobutyric acid (GABA), putrescine content, and glutamate decarboxylase activity whereas diamine oxidase and polyamine oxidase activities declined by 1.69-1.88-fold and 1.52-1.86-fold, respectively. Se alone or in combination with As improved plant growth, RWC, GB, choline, putrescine, and sugars; lowered proline and GABA; and showed a reverse trend of enzyme activities related to their metabolism than respective As treatments. As stress resulted in a higher accumulation of osmolytes to combat its stress which was further modulated by the Se application. Hence, the current investigation suggested the role of osmoprotectants in Se-induced amelioration of As toxicity in rice plants.

Dietary polyamine intake and all-cause and cause-specific mortality in Japanese adults in the Takayama study

Epidemiological studies on the potential health effects of dietary polyamines are scarce. The present study aimed to estimate habitual intake of polyamines (putrescine, spermidine and spermine) and examine whether spermidine intake is inversely associated with all-cause and cause-specific mortality in a population-based cohort study in Japan. The study included 13 355 men and 15 724 women aged 35 years and older. Diet was assessed via a validated FFQ at the baseline in 1992. The intake of polyamines was estimated mainly using databases of polyamine content in foods consumed among Japanese population. Sex-specific hazard ratios (HR) and 95 % CI for all-cause and cause-specific mortality were estimated according to polyamine quartiles. During 16 years of follow-up, 2901 deaths in men and 2438 in women occurred. The intake of any polyamine was not significantly associated with all-cause or cause-specific mortality after controlling for covariates in men and women. There was a suggestive positive association between spermidine intake and cancer mortality in women: HR for the highest v. lowest quartile were 1·38 (95 % CI (0·99, 1·93); Ptrend = 0·02). Our results did not provide support for the notion that dietary spermidine has beneficial effects on mortality. Further studies on dietary polyamines and longevity, as well as the morbidity of specific diseases, including cancer, are needed across populations with different dietary habits.

Melatonin alleviates Hg toxicity by modulating redox homeostasis and the urea cycle in moss

Mercury (Hg) is a highly toxic metal and can cause severe damage to many organisms under natural conditions. As an effective free radical scavenger and antioxidant, Melatonin (MT) has played important protective roles in alleviating oxidative damage caused by environmental cues including heavy metal stress in plants. However, the detailed mechanisms of melatonin in alleviating Hg toxicity still remain unclear in plants. Our results showed that the application of melatonin greatly reduced the concentrations of total and intracellular Hg in Taxiphyllum taxirameum. Meanwhile, melatonin significantly improved the antioxidant capacity and thus alleviated oxidative damage to the chloroplasts of T. taxirameum under Hg stress. Metabolic pathway analysis further revealed that melatonin-treated plants exhibited higher levels of 48 metabolites, including sugars, amino acids, and lipids, than non-melatonin-treated plants under Hg stress. Additionally, we further found that melatonin addition greatly improved the concentrations of four organic acids and three amino acids (Orn, Cit and Arg) related to the urea cycle, and thereby changed the levels of putrescine (Put) and spermidine (Spd) in T. taxirameum exposed to Hg stress. Further experiments showed that the high concentration of Put dramatically caused oxidative damage under Hg stress, while Spd effectively alleviated Hg toxicity in T. taxirameum. Taken together, this study provides new insight into the underlying mechanisms of melatonin in alleviating heavy metal toxicity in plants.

Intracellular polyamine depletion induces N-linked galactosylation of the monoclonal antibody produced by CHO DP-12 cells

The heterogeneity of the N-linked glycan profile of therapeutic monoclonal antibodies (mAbs) derived from animal cells affects therapeutic efficacy and, therefore, needs to be appropriately controlled during the manufacturing process. In this study, we examined the effects of polyamines on the N-linked glycan profiles of mAbs produced by CHO DP-12 cells. Normal cell growth of CHO DP-12 cells and their growth arrest by α-difluoromethylornithine (DFMO), an inhibitor of the polyamine biosynthetic pathway, was observed when 0.5% fetal bovine serum was added to serum-free medium, despite the presence of cadaverine and aminopropylcadaverine, instead of putrescine and spermidine in cells. Polyamine depletion by DFMO increased IgG galactosylation, accompanied by β1,4-galactosyl transferase 1 (B4GAT1) mRNA elevation. Additionally, IgG production in polyamine-depleted cells was reduced by 30% compared to that in control cells. Therefore, we examined whether polyamine depletion induces an ER stress response. The results indicated increased expression levels of chaperones for glycoprotein folding in polyamine-depleted cells, suggesting that polyamine depletion causes ER stress related to glycoprotein folding. The effect of tunicamycin, an ER stress inducer that inhibits N-glycosylation, on the expression of B4GALT1 mRNA was examined. Tunicamycin treatment increased B4GALT1 mRNA expression. These results suggest that ER stress caused by polyamine depletion induces B4GALT1 mRNA expression, resulting in increased IgG galactosylation in CHO cells. Thus, introducing polyamines, particularly SPD, to serum-free CHO culture medium for CHO cells may contribute to consistent manufacturing and quality control of antibody production.

Co-administration of curcumin and polyamines in high-fat diet induced obese rats: Assessment of changes in serum polyamine levels and some tissue parameters

Obesity is a non-communicable chronic disease that continues to increase around the world. Recently, it has been shown that curcumin positively affects lipid, energy metabolism, and body weight change. Moreover, polyamines are aliphatic polycations, which can be found in all mammalian cells and foods and have been shown to prevent obesity through many different mechanisms. However, whether the co-administration of curcumin and polyamines has synergistic effects has yet to be clarified. Our study aimed to examine the effects of curcumin and polyamines on obesity and to assess the changes in serum polyamine levels and tissue parameters. 28 Sprague-Dawley male rats were fed a high-fat diet for 10 weeks to develop obesity, and then they were randomly divided into 4 groups as the control group (CONT), curcumin group (CUR), polyamine group (POL), curcumin and polyamine group (CUR+POL) and supplements were administered for 6 weeks. As a result, the lowest feed consumption in rats was recorded in the CUR+POL group, and the group with the lowest weight after supplements was the POL group, then the CUR+POL, CONT, and CUR groups, respectively. N-acetyl putrescine and GABA levels increased significantly after obesity development. The total histopathological score in fat, liver, and kidney tissues increased significantly in the CONT group. In the CUR+POL group, damage to the tissues was in the direction of recovery compared to the other groups, and the expression of NF-κB was significantly low. These results suggest that combined curcumin and polyamines may have protective effects.

Toxicological effects of the Curatella americana extract in embryo development of female pups from diabetic rats

Maternal diabetes can influence the development of offspring during fetal life and postnatally. Curatella americana is a plant used as a menstrual cycle regulator and to prevent diabetes. This study evaluates the effects of C. americana aqueous extract on the estrous cycle and preimplantation embryos of adult female pups from diabetic rats. Female Sprague Dawley newborn rats received Streptozotocin or vehicle (citrate buffer). At adulthood, were submitted to the Oral Glucose Tolerance Test, and mated. The female rats were obtained and were distributed into four experimental groups: OC and OC/T represent female pups of control mothers and received water or plant extract, respectively; OD and OD/T represent female pups of diabetic mothers and received water or plant extract, respectively. The estrous cycle was followed for 10 days, the rats were mated and on gestational day 4 was performed preimplantation embryo analysis. Phenolic composition and biogenic amines in the extract were analyzed about the influence of the thermal process. The female pups from diabetic dams exhibited glucose intolerance, irregular estral cycle and a higher percentage of pre-embryos in delayed development (morula stage). After C. americana treatment, OD/T group no present a regular estrous cycle. Furthermore, the infusion process increases phenolic compounds and biogenic amines levels, which can have anti-estrogenic effect, anticipates the early embryonic development, and impair pre-implantation embryos. Thus, the indiscriminate use of medicinal plants should be avoided in any life phases by women, especially during pregnancy.

Polyamines and hormesis: Making sense of a dose response dichotomy

The diverse biological effects of polyamines (putrescine, spermidine and spermine) were reviewed in the context of hormesis in an integrative manner for the first time. The findings illustrate that each of these polyamines commonly induces hormetic dose responses in a wide range of biological models and types of cells for multiple endpoints in numerous plant species and animal models. Plant research emphasized preconditioning experimental studies in which the respective polyamines conferred some protection against the damaging effects of a broad range of environmental stressors such as drought, salinity, cold/heat, heavy metals and UV-damage in an hormetic manner. Polyamine-based animal hormesis studies emphasized biomedical endpoints such as longevity and neuroprotection. These findings have important biological and biomedical implications and should guide experimental designs of low dose investigations.

Low-temperature acclimation related with developmental regulations of polyamines and ethylene metabolism in wheat recombinant inbred lines

Winter survival is determined by complicated developmental regulations enabling wheat to adjust their transcriptome and metabolome to develop low temperature (LT) tolerance. The aim of the study was to clarify the metabolic responses developmentally regulated in six F6 recombinant inbred lines from a cross between Pishtaz (spring parent) and Mironovskaya 808 (winter parent). Spring genotypes, including pishtaz, RILs 4006 and 4014 showed lower LT tolerance, PAs (except the spermin), GABA and proline contents and DPPH• scavenging capacity. In these genotypes, genes and enzymes involved in the pathways of PAs and GABA degradation and ethylene biosynthesis were more active than other genotypes. RILs 4012 and 4016 with short vernalization displayed higher tolerance and lower H2O2 content compared to Pishtaz. Strong vernalization requirements in winter and facultative genotypes (Mironovskaya 808 parent and RILs 4003 and 4005) results in up-regulation of the metabolites and genes involved in PAs and GABA biosynthesis pathways (particularly when vernalization fulfillment occurred) to establish high tolerance as compared to genotypes without vernalization requirement. LT tolerance in all genotypes significantly decreased after vernalization fulfillment in February. Results indicated that LT tolerance was partly validated from developmental regulation of PAs, GABA, and ethylene metabolism during venalization and LT acclimation.

Evidence of polyamines mediated 2-acetyl-1-pyrroline biosynthesis in aromatic rice rhizospheric fungal species Aspergillus niger

Rhizosphere soil of aromatic rice inhabits different fungal species that produce many bioactive metabolites including 2-acetyl-1-pyrroline (2AP). The mechanism for the biosynthesis of 2AP in the fungal system is still elusive. Hence, the present study investigates the role of possible nitrogen (N) precursors such as some amino acids and polyamines as well as the enzymes involved in 2AP synthesis in the fungal species isolated from the rhizosphere of aromatic rice varieties. Three fungal isolates were found to synthesize 2AP (0.32-1.07 ppm) and maximum 2AP was synthesized by Aspergillus niger (1.07 ppm) isolated from rhizosphere of Dehradun Basmati (DB). To determine the N source for 2AP synthesis, various N sources such as proline, glutamate, ornithine putrescine, spermine, and spermidine were used in place of putrescine in the synthetic medium (Syn18). The results showed that maximum 2AP synthesis was found with putrescine (1.07 ppm) followed by spermidine (0.89 ppm) and spermine (0.84 ppm). Further, LC-QTOF-MS analysis revealed the mobilization of spermine and spermidine into the putrescine, indicating that putrescine is the key N source for 2AP synthesis. Moreover, higher enzyme activity of DAO, PAO, and ODC as well as higher content of methylglyoxal metabolite in the A. niger NFCCI 5060 as compared to A. niger NFCCI 4064 (control) suggests the prominent role of these enzymes in the synthesis of 2AP. In conclusion, this study showed evidence of the polyamines mediated 2AP biosynthesis in A. niger NFCCI 5060.

Purification and characterization of tomato arginine decarboxylase and its inhibition by the bacterial small molecule phevamine A

Polyamines play essential roles in plant growth and survival. Arginine decarboxylase (ADC), which converts arginine to agmatine, catalyzes the first step in polyamine biosynthesis from arginine. However, few biochemical studies with purified plant ADCs have been conducted to evaluate their catalytic efficiency. Tomato genome encodes two arginine decarboxylases: SlADC1 and SlADC2, which are critical for growth, development, and immune responses against bacterial pathogens. We expressed and purified soluble SlADC1 as a recombinant protein fused with maltose-binding protein tag from E. coli Rosetta 2(DE3) cells. Using the purified fusion protein, we characterized the biochemical properties of SlADC1 in vitro and explored it as a target of the bacterial small molecule phevamine A. We confirmed that the activity of SlADC1 depends on the cofactor pyridoxal 5'-phosphate. SlADC1 is specific toward l-arginine and its kinetic parameters were measured using a liquid chromatography-mass spectrometry method. Phevamine A is a competitive inhibitor of SlADC1 and reduces the activity of SlADC1 at high micromolar concentrations. Our purification and biochemical characterization of SlADC1 sets the stage for inhibition studies of this enzyme.

Polyamine-producing bacteria inhibit the absorption of Cd by spinach and alter the bacterial community composition of rhizosphere soil

Polyamines (PAs) are small aliphatic nitrogenous bases with strong biological activity that participate in plant stress response signaling and the alleviation of damage from stress. Herein, the effects of the PA-producing bacterium Bacillus megaterium N3 and PAs on the immobilization of Cd and inhibition of Cd absorption by spinach and the underlying mechanisms were studied. A solution test showed that strain N3 secreted spermine and spermidine in the presence of Cd. Both strain N3 and the PAs (spermine+spermidine) immobilized Cd and increased the pH of the solution. Untargeted metabolomics results showed that strain N3 secreted PAs, N1-acetylspermidine, 3-indolepropionic acid, indole-3-acetaldehyde, cysteinyl-gamma-glutamate, and choline, which correlated with plant growth promotion and Cd immobilization. A pot experiment showed that rhizosphere soil inoculation with strain N3 and PAs improved spinach dry weight and reduced spinach Cd absorption compared with the control. These positive effects were likely due to the increase in rhizosphere soil pH and NH4+-N and PA contents, which can be attributed primarily to Cd immobilization. Moreover, inoculation with strain N3 more effectively inhibited the absorption of Cd by spinach than spraying PAs, mainly because strain N3 enabled a better relative abundance of bacteria (Microvirga, Pedobacter, Bacillus, Brevundimonas, Pseudomonas, Serratia, Devosid, and Aminobacter), that have been reported to have the ability to resist heavy metals and produce PAs. Strain N3 regulated the structure of rhizosphere functional bacterial communities and inhibited Cd uptake by spinach. These results provide a theoretical basis for the prevention of heavy metal absorption by vegetables using PA-producing bacteria.

Cytotoxicity of poly-guanidine in medulloblastoma cell lines

Medulloblastoma (MB) is the most common pediatric brain tumor. The therapy frequently causes serious side effects, and new selective therapies are needed. MB expresses hyper sialylation, a possible target for selective therapy. The cytotoxic efficacy of a poly guanidine conjugate (GuaDex) incubated with medulloblastoma cell cultures (DAOY and MB-LU-181) was investigated. The cells were incubated with 0.05-8 µM GuaDex from 15 min to 72 h. A fluorometric cytotoxicity assay (FMCA) measured the cytotoxicity. Labeled GuaDex was used to study tumor cell interaction. FITC-label Sambucus nigra confirmed high expression of sialic acid (Sia). Immunofluorescence microscopy was used to visualize the cell F-actin and microtubules. The cell interactions were studied by confocal and fluorescence microscopy. Annexin-V assay was used to detect apoptosis. Cell cycle analysis was done by DNA content determination. A wound-healing migration assay determined the effects on the migratory ability of DAOY cells after GuaDex treatment. IC50 for GuaDex was 223.4 -281.1 nM. FMCA showed potent growth inhibition on DAOY and MB-LU-181 cells at 5 uM GuaDex after 4 h of incubation. GuaDex treatment induced G2/M phase cell cycle arrest. S. nigra FITC-label lectin confirmed high expression of Sia on DAOY medulloblastoma cells. The GuaDex treatment polymerized the cytoskeleton (actin filaments and microtubules) and bound to DNA, inducing condensation. The Annexin V assay results were negative. Cell migration was inhibited at 0.5 µM GuaDex concentration after 24 h of incubation. GuaDex showed potent cytotoxicity and invasion-inhibitory effects on medulloblastoma cells at low micromolar concentrations. GuaDex efficacy was significant and warrants further studies.

Arbuscular mycorrhizal fungi as an effective approach to enhance the growth and metabolism of soybean plants under thallium (TI) toxicity

Thallium (TI) is a toxic metal that can trigger harmful impacts on growth and metabolism of plants. Utilizing arbuscular mycorrhizal fungi (AMF) proves to be an effective strategy for alleviating heavy metal toxicity in plants. To this end, AMF were applied to mitigate TI toxic effects on the growth, primary and secondary metabolism of soybean plants. Here, TI stress inhibited the growth and photosynthetic parameters of soybean plants. It also increased the oxidative damage as demonstrated by increased levels of oxidative markers, (MDA and lipoxygenase (LOX) activity). However, AMF could mitigate the reduction in growth and photosynthesis induced by TI, as well as the induction of oxidative damage. To overcome TI toxicity, AMF increased the levels and metabolism of osmolytes such as proline in soybean plants. This was in line with the increased activities of key enzymes that involved in proline biosynthesis (e.g., P5CS (pyrroline-5-carboxylate synthetase), P5CR (pyrroline-5-carboxylate reductase) and OAT (ornithine aminotransferase) under the AMF and/or TI treatments. Furthermore, soybean plants could benefit from the synergism between AMF and TI to enhance the contents of individual (e.g., spermine and spermidine) and total polyamines as well as their metabolic enzymes (e.g., arginine decarboxylase and ornithine decarboxylase). Overall, the combined application of AMF emerges as a viable approach for alleviating TI toxicity in soybean plants.

Modulating the polyamine/hypusine axis controls generation of CD8+ tissue-resident memory T cells

Glutaminolysis is a hallmark of the activation and metabolic reprogramming of T cells. Isotopic tracer analyses of antigen-activated effector CD8+ T cells revealed that glutamine is the principal carbon source for the biosynthesis of polyamines putrescine, spermidine, and spermine. These metabolites play critical roles in activation-induced T cell proliferation, as well as for the production of hypusine, which is derived from spermidine and is covalently linked to the translation elongation factor eukaryotic translation initiation factor 5A (eIF5A). Here, we demonstrated that the glutamine/polyamine/hypusine axis controlled the expression of CD69, an important regulator of tissue-resident memory T cells (Trm). Inhibition of this circuit augmented the development of Trm cells ex vivo and in vivo in the BM, a well-established niche for Trm cells. Furthermore, blocking the polyamine/hypusine axis augmented CD69 expression as well as IFN-γ and TNF-α production in (a) human CD8+ T cells from peripheral blood and sarcoma tumor infiltrating lymphocytes and (b) human CD8+ CAR-T cells. Collectively, these findings support the notion that the polyamine-hypusine circuit can be exploited to modulate Trm cells for therapeutic benefit.

Regulation of ethylene metabolism in tomato under salinity stress involving linkages with important physiological signaling pathways

The tomato is well-known for its anti-oxidative and anti-cancer properties, and with a wide range of health benefits is an important cash crop for human well-being. However, environmental stresses (especially abiotic) are having a deleterious effect on plant growth and productivity, including tomato. In this review, authors describe how salinity stress imposes risk consequences on growth and developmental processes of tomato through toxicity by ethylene (ET) and cyanide (HCN), and ionic, oxidative, and osmotic stresses. Recent research has clarified how salinity stress induced-ACS and - β-CAS expressions stimulate the accumulation of ET and HCN, wherein the action of salicylic acid (SA),compatible solutes (CSs), polyamines (PAs) and ET inhibitors (ETIs) regulate ET and HCN metabolism. Here we emphasize how ET, SA and PA cooperates with mitochondrial alternating oxidase (AOX), salt overly sensitive (SOS) pathways and the antioxidants (ANTOX) system to better understand the salinity stress resistance mechanism. The current literature evaluated in this paper provides an overview of salinity stress resistance mechanism involving synchronized routes of ET metabolism by SA and PAs, connecting regulated network of central physiological processes governing through the action of AOX, β-CAS, SOS and ANTOX pathways, which might be crucial for the development of tomato.

Peptide fraction from B. jararaca snake venom protects against oxidative stress-induced changes in neuronal PC12 cell but not in astrocyte-like C6 cell

Venom-derived proteins and peptides have prevented neuronal cell loss, damage, and death in the study of neurodegenerative disorders. The cytoprotective effects of the peptide fraction (PF) from Bothrops jararaca snake venom were evaluated against oxidative stress changes in neuronal PC12 cells and astrocyte-like C6 cells. PC12 and C6 cells were pre-treated for 4 h with different concentrations of PF, and then H2O2 was added (0.5 mM in PC12 cells; 0.4 mM in C6 cells) and incubated for 20 h more. In PC12 cells, PF at 0.78 μg mL-1 increased viability (113.6 ± 6.3%) and metabolism (96.3 ± 10.3%) cell against H2O2-induced neurotoxicity (75.6 ± 5.8%; 66.5 ± 3.3%, respectively), reducing oxidative stress markers such as ROS generation, NO production, and arginase indirect activity through urea synthesis. Despite that, PF showed no cytoprotective effects in C6 cells, but potentiated the H2O2-induced damage at a concentration lower than 0.07 μg mL-1. Furthermore, the role of metabolites derived from L-arginine metabolism was verified in PF-mediated neuroprotection in PC12 cells, using specific inhibitors of two of the key enzymes in the L-arginine metabolic pathway: the α-Methyl-DL-aspartic acid (MDLA) to argininosuccinate synthetase (AsS), responsible for the recycling of L-citrulline to L-arginine; and, L-NΩ-Nitroarginine methyl ester (L-Name) to nitric oxide synthase (NOS), which catalyzes the synthesis of NO from L-arginine. The inhibition of AsS and NOS suppressed PF-mediated cytoprotection against oxidative stress, indicating that its mechanism is dependent on the production pathway of L-arginine metabolites such as NO and, more importantly, polyamines from ornithine metabolism, which are involved in the neuroprotection mechanism described in the literature. Overall, this work provides novel opportunities for evaluating whether the neuroprotective properties of PF shown in particular neuronal cells are sustained and for exploring potential drug development pathways for the treatment of neurodegenerative diseases.

Polyamine as a microenvironment factor in resistance to antibiotics

One of the main issues in modern medicine is the decrease in the efficacy of antibiotic therapy against resistant microorganisms. The advent of antimicrobial resistance has added significantly to the impact of infectious diseases, in number of infections, as well as added healthcare costs. The development of antibiotic tolerance and resistance is influenced by a variety of environmental variables, and it is important to identify these environmental factors as part of any strategy for combating antibiotic resistance. The review aims to emphasize that biogenic polyamines are one of such environmental cues that impacts the antibiotic resistance in bacteria. The biogenic polyamines can help bacteria acquire resistance to antibiotics either by regulating the level of number of porin channels in the outer membrane, by modifying the outer membrane liposaccharides or by protecting macromolecule from antibiotic stress. Thus, understanding the way polyamines function in bacteria can thus be beneficial while designing the drugs to combat diseases.

Gut microbiota and anti-aging: Focusing on spermidine

The human gut microbiota plays numerous roles in regulating host growth, the immune system, and metabolism. Age-related changes in the gut environment lead to chronic inflammation, metabolic dysfunction, and illness, which in turn affect aging and increase the risk of neurodegenerative disorders. Local immunity is also affected by changes in the gut environment. Polyamines are crucial for cell development, proliferation, and tissue regeneration. They regulate enzyme activity, bind to and stabilize DNA and RNA, have antioxidative properties, and are necessary for the control of translation. All living organisms contain the natural polyamine spermidine, which has anti-inflammatory and antioxidant properties. It can regulate protein expression, prolong life, and improve mitochondrial metabolic activity and respiration. Spermidine levels experience an age-related decrease, and the development of age-related diseases is correlated with decreased endogenous spermidine concentrations. As more than just a consequence, this review explores the connection between polyamine metabolism and aging and identifies advantageous bacteria for anti-aging and metabolites they produce. Further research is being conducted on probiotics and prebiotics that support the uptake and ingestion of spermidine from food extracts or stimulate the production of polyamines by gut microbiota. This provides a successful strategy to increase spermidine levels.

EPLIN-β is a novel substrate of ornithine decarboxylase antizyme 1 and mediates cellular migration

Polyamines promote cellular proliferation. Their levels are controlled by ornithine decarboxylase antizyme 1 (Az1, encoded by OAZ1), through the proteasome-mediated, ubiquitin-independent degradation of ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis. Az1-mediated degradation of other substrates such as cyclin D1 (CCND1), DNp73 (TP73) or Mps1 regulates cell growth and centrosome amplification, and the currently known six Az1 substrates are all linked with tumorigenesis. To understand whether Az1-mediated protein degradation might play a role in regulating other cellular processes associated with tumorigenesis, we employed quantitative proteomics to identify novel Az1 substrates. Here, we describe the identification of LIM domain and actin-binding protein 1 (LIMA1), also known as epithelial protein lost in neoplasm (EPLIN), as a new Az1 target. Interestingly, between the two EPLIN isoforms (α and β), only EPLIN-β is a substrate of Az1. The interaction between EPLIN-β and Az1 appears to be indirect, and EPLIN-β is degraded by Az1 in a ubiquitination-independent manner. Az1 absence leads to elevated EPLIN-β levels, causing enhanced cellular migration. Consistently, higher LIMA1 levels correlate with poorer overall survival of colorectal cancer patients. Overall, this study identifies EPLIN-β as a novel Az1 substrate regulating cellular migration.

Age-associated polyamines in peripheral blood cells and plasma in 20 to 70 years of age subjects

Dietary polyamines have been associated with slowing ageing processes and various pathologies, raising the importance of establishing reference values at different ages throughout life. This study aimed to analyse age-dependent variations in polyamine content using peripheral blood cells and plasma in a healthy and homogeneous population. Peripheral blood of 193 volunteers of both sexes (20-70 years), selected by convenience, was processed to separate cells and plasma. A pre-column derivatization method was used to determine the amines by HPLC (nmol or pmol/mg protein or nmol/ml) to analyse their association with the age (continuous or ordinal in decades) of the subjects. Putrescine and spermine weakly declined significantly in mononuclear cells with age. In erythrocytes and plasma, putrescine showed an evident decrease in the 60-70-year-old group compared to the rest. The ratios between polyamines, mainly in erythrocytes, decreased in the 60-70 years age group and increased the ratio of putrescine in mononuclear cells/erythrocytes. The ratio of putrescine in mononuclear cells/erythrocytes was higher in the 60-70-year-old age group than in the rest. In a sample of subjects (20-29 vs. 60-70 years), whole blood polyamines were not significantly different when differences existed in erythrocytes. Polyamine homeostasis in blood cells and plasma changed with age. Putrescine declined in mononuclear cells and decreased in erythrocytes and plasma in the decade of the 60 s. Further studies should establish an age-dependent phenotype and whether polyamines' supplementation could restore the decreased values and be associated with long-term overall biological benefits.

TGase-induced Cd tolerance by boosting polyamine, nitric oxide, cell wall composition and phytochelatin synthesis in tomato

In highly intensive greenhouse vegetable production, soil acidification was caused by excessive fertilization, increasing cadmium (Cd) concentrations in the vegetables, which bears environmental hazards and is a negative influence on vegetables and humans. Transglutaminases (TGases), a central mediator for certain physiological effects of polyamines (PAs) in the plant kingdom, play important roles in plant development and stress response. Despite increased research on the crucial role of TGase in protecting against environmental stresses, relatively little is known about the mechanisms of Cd tolerance. In this study, we found, TGase activity and transcript level, which was upregulated by Cd, and TGase-induced Cd tolerance related to endogenous bound PAs increase and formation of nitric oxide (NO). Plant growth of tgase mutants was hypersensitive to Cd, chemical complementation by putrescine, sodium nitroprusside (SNP, nitric oxide donor) or gain of function TGase experiments restore Cd tolerance. α-diflouromethylornithine (DFMO, a selective ODC inhibitor) and 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, NO scavenger), were respectively found declined drastically endogenous bound PA and NO content in TGase overexpression plants. Likewise, we reported that TGase interacted with polyamine uptake protein 3 (Put3), and the silencing of Put3 largely reduced TGase-induced Cd tolerance and bound PAs formation. This salvage strategy depends on TGase-regulated synthesis of bound PAs and NO that is able to positively increase the concentration of thiol and phytochelatins, elevate Cd in the cell wall, as well as induce the levels of expression Cd uptake and transport genes. Collectively, these findings indicate that TGase-mediated enhanced levels of bound PA and NO acts as a vital mechanism to protect the plant from Cd-caused toxicity.

Transcriptomic analysis revealed the candidate metabolic pathways and genes associated with cold tolerance in a mutant without anthocyanin accumulation in common vetch (Vicia sativa L.)

Common vetch (Vicia sativa L.) is a leguminous crop used to feed livestock with vegetative organs or fertilize soils by returning to the field. Survival of fall-seeded plants is often affected by freezing damage during overwintering. This study aims to investigate the transcriptomic profiling in response to cold in a mutant with reduced accumulation of anthocyanins under normal growth and low-temperature conditions for understanding the underlying mechanisms. The mutant had increased cold a tolerance with higher survival rate and biomass during overwintering compared to the wild type, which led to increased forage production. Transcriptomic analysis in combination with qRT-PCR and physiological measurements revealed that reduced anthocyanins accumulation in the mutant resulted from reduced expression of serial genes involving in anthocyanin biosynthesis, which led to the altered metabolism, with an increased accumulation of free amino acids and polyamines. The higher levels of free amino acids and proline in the mutant under low temperature were associated with improved cold tolerance. The altered expression of some genes involved in ABA and GA signaling was also associated with increased cold tolerance in the mutant.

Restoring polyamine levels by supplementation of spermidine modulates hepatic immune landscape in murine model of NASH

AIMS

To determine if changes in polyamines metabolism occur during non-alcoholic steatohepatitis (NASH) in human patients and mice, as well as to assess systemic and liver-specific effects of spermidine administration into mice suffering from advanced NASH.

MATERIALS AND METHODS

Human fecal samples were collected from 50 healthy and 50 NASH patients. For the preclinical studies C57Bl6/N male mice fed GAN or NIH-31 diet for 6 months were ordered from Taconic and liver biopsy was performed. Based on severity of liver fibrosis, body composition and body weight, the mice from both dietary groups were randomized into another two groups: half receiving 3 mM spermidine in drinking water, half normal water for subsequent 12 weeks. Body weight was measured weekly and glucose tolerance and body composition were assessed at the end. Blood and organs were collected during necropsy, and intrahepatic immune cells were isolated for flow cytometry analysis.

RESULTS

Metabolomic analysis of human and murine feces confirmed that levels of polyamines decreased along NASH progression. Administration of exogenous spermidine to the mice from both dietary groups did not affect body weight, body composition or adiposity. Moreover, incidence of macroscopic hepatic lesions was higher in NASH mice receiving spermidine. On the other hand, spermidine normalized numbers of Kupffer cells in the livers of mice suffering from NASH, although these beneficial effects did not translate into improved liver steatosis or fibrosis severity.

CONCLUSION

Levels of polyamines decrease during NASH in mice and human patients but spermidine administration does not improve advanced NASH.

Combined inhibition of polyamine metabolism and eIF5A hypusination suppresses colorectal cancer growth through a converging effect on MYC translation

A key mechanism driving colorectal cancer (CRC) development is the upregulation of MYC and its targets, including ornithine decarboxylase (ODC), a master regulator of polyamine metabolism. Elevated polyamines promote tumorigenesis in part by activating DHPS-mediated hypusination of the translation factor eIF5A, thereby inducing MYC biosynthesis. Thus, MYC, ODC and eIF5A orchestrate a positive feedback loop that represents an attractive therapeutic target for CRC therapy. Here we show that combined inhibition of ODC and eIF5A induces a synergistic antitumor response in CRC cells, leading to MYC suppression. We found that genes of the polyamine biosynthesis and hypusination pathways are significantly upregulated in colorectal cancer patients and that inhibition of ODC or DHPS alone limits CRC cell proliferation through a cytostatic mechanism, while combined ODC and DHPS/eIF5A blockade induces a synergistic inhibition, accompanied to apoptotic cell death in vitro and in mouse models of CRC and FAP. Mechanistically, we found that this dual treatment causes complete inhibition of MYC biosynthesis in a bimodal fashion, by preventing translational elongation and initiation. Together, these data illustrate a novel strategy for CRC treatment, based on the combined suppression of ODC and eIF5A, which holds promise for the treatment of CRC.

Putrescine-functionalized carbon quantum dot (put-CQD) nanoparticle: A promising stress-protecting agent against cadmium stress in grapevine (Vitis vinifera cv. Sultana)

Due to their sessile nature, plant cannot escape from stress factors in their growing environment, in either biotic or abiotic nature. Amid the abiotic stress factors; high levels of soil cadmium (Cd) impose heavy metal stress on plants, resulting in critical injuries and reduced agronomic performance. In order to buffer the adverse effects of Cd stress, novel nanoparticles (NP) have been applied and notable improvements have been reported. According to the literature, the protective roles of polyamines (e.g., Putrescine; Put) and carbon quantum dots (CQD) have been reported with respect to the plant productivity under either stress or non-stress conditions. Those reports led us to hypothesize that the conjugation of Put and CQD (Put-CQD NPs) might lead to further augmented performance of plants under stress and non-stress conditions. In this regard, we successfully synthesized a novel nanomaterial Put-CQD NPs. In this respect, Put (50 mg L^-1), CQD (50 mg L^-1) and Put-CQD NPs (25 and 50 mg L^-1) were sprayed in 'Sultana' grapevines under Cd stress (10 mg kg^-1). As expected, upon stress, Cd content in leaf and root tissues increased by 103.40% and 65.15%, respectively (p < 0.05). The high uptake and accumulation of Cd in plant tissues were manifested in significant alterations of physiological and biochemical attributes of the plant. Concerning stress markers, Cd stress caused increases in content of induced MDA, H₂O₂, and proline as well as electrolyte leakage rate. As expected, Cd stress caused critical reductions in fresh and dry leaf weight by 21.31% and 42.34%, respectively (p < 0.05). On the other hand, both Put-CQD NPs increased fresh and dry leaf weigh up to approximately 30%. The Cd-mediated disturbances in photosynthetic pigments and chlorophyll fluorescence were buffered with Put-CQD NPs. Of the defence system, enzymatic (SOD, APX, GP) as well as anthocyanin and phenolics were induced by both Cd stress and Put-CQD NPs (p < 0.05). On the other hand, Cd stress reduced content of polyamines (putrescine (Put), spermine (Spm) and spermidine (Spd) by 39.28%, 53.36%, and 39.26%, respectively (p < 0.05). However, the reduction levels were buffered by the treatments. Considering the effectiveness of both NP concentrations, the lower dose (25 mg L^-1) could be considered as an optimal concentration. To our knowledge, this is the first report of its kind as a potential agent to reduce the adverse effects of Cd stress in grapevines.

A new 68Ga-labeled ornithine derivative for PET imaging of ornithine metabolism in tumors

Ornithine metabolism plays a vital role in tumorigenesis. For cancer cells, ornithine is mainly used as a substrate for ornithine decarboxylase (ODC) for the synthesis of polyamines. The ODC as a key enzyme of polyamine metabolism has become an important target for cancer diagnosis and treatment. To non-invasively detect the levels of ODC expression in malignant tumors, we have synthesized a novel ⁶⁸Ga-labeled ornithine derivative ([⁶⁸Ga]Ga-NOTA-Orn). The synthesis time of [⁶⁸Ga]Ga-NOTA-Orn was about 30 min with a radiochemical yield of 45-50% (uncorrected), and the radiochemical purity was > 98%. [⁶⁸Ga]Ga-NOTA-Orn was stable in saline and rat serum. Cellular uptake and competitive inhibition assays using DU145 and AR42J cells demonstrated that the transport pathway of [⁶⁸Ga]Ga-NOTA-Orn was similar to that of L-ornithine, and it could interact with the ODC after transporting into the cell. Biodistribution and micro-positron emission tomography (Micro-PET) imaging studies showed that [⁶⁸Ga]Ga-NOTA-Orn exhibited rapid tumor uptake and was rapidly excreted through the urinary system. All above results suggested that [⁶⁸Ga]Ga-NOTA-Orn is a novel amino acid metabolic imaging agent with great potential of tumor diagnosis.

Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a novel mouse model of Snyder-Robinson Syndrome

Polyamines (putrescine, spermidine, and spermine) are essential molecules for normal cellular functions and are subject to strict metabolic regulation. Mutations in the gene encoding spermine synthase (SMS) lead to accumulation of spermidine in an X-linked recessive disorder known as Snyder-Robinson syndrome (SRS). Presently, no treatments exist for this rare disease that manifests with a spectrum of symptoms including intellectual disability, developmental delay, thin habitus, and low muscle tone. The development of therapeutic interventions for SRS will require a suitable disease-specific animal model that recapitulates many of the abnormalities observed in patients. Here, we characterize the molecular, behavioral, and neuroanatomical features of a mouse model with a missense mutation in Sms gene that results in a glycine-to-serine substitution at position 56 (G56S) of the SMS protein. Mice harboring this mutation exhibit a complete loss of SMS protein and elevated spermidine/spermine ratio in skeletal muscles and the brain. In addition, the G56S mice demonstrate increased anxiety, impaired learning, and decreased explorative behavior in fear conditioning, Morris water maze, and open field tests, respectively. Furthermore, these mice failed to gain weight over time and exhibit abnormalities in brain structure and bone density. Transcriptomic analysis of the cerebral cortex revealed downregulation of genes associated with mitochondrial oxidative phosphorylation and ribosomal protein synthesis. Our findings also revealed impaired mitochondrial bioenergetics in fibroblasts isolated from the G56S mice, indicating a correlation between these processes in the affected mice. Collectively, our findings establish the first in-depth characterization of an SRS preclinical mouse model that identifies cellular processes that could be targeted for future therapeutic development.

Diagnostic metabolomic profiling of Parkinson's disease biospecimens

BACKGROUND

Reliable and sensitive biomarkers are needed for enhancing and predicting Parkinson's disease (PD) diagnosis.

OBJECTIVE

To investigate comprehensive metabolomic profiling of biochemicals in CSF and serum for determining diagnostic biomarkers of PD.

METHODS

Fifty subjects, symptomatic with PD for ≥5 years, were matched to 50 healthy controls (HCs). We used ultrahigh-performance liquid chromatography linked to tandem mass spectrometry (UHPLC-MS/MS) for measuring relative concentrations of ≤1.5 kDalton biochemicals. A reference library created from authentic standards facilitated chemical identifications. Analytes underwent univariate analysis for PD association, with false discovery rate-adjusted p-value (≤0.05) determinations. Multivariate analysis (for identifying a panel of biochemicals discriminating PD from HCs) used several biostatistical methods, including logistic LASSO regression.

RESULTS

Comparing PD and HCs, strong differentiation was achieved from CSF but not serum specimens. With univariate analysis, 21 CSF compounds exhibited significant differential concentrations. Logistic LASSO regression led to selection of 23 biochemicals (11 shared with those determined by the univariate analysis). The selected compounds, as a group, distinguished PD from HCs, with Area-Under-the-Receiver-Operating-Characteristic (ROC) curve of 0.897. With optimal cutoff, logistic LASSO achieved 100% sensitivity and 96% specificity (and positive and negative predictive values of 96% and 100%). Ten-fold cross-validation gave 84% sensitivity and 82% specificity (and 82% positive and 84% negative predictive values). From the logistic LASSO-chosen regression model, 2 polyamine metabolites (N-acetylcadaverine and N-acetylputrescine) were chosen and had the highest fold-changes in comparing PD to HCs. Another chosen biochemical, acisoga (N-(3-acetamidopropyl)pyrrolidine-2-one), also is a polyamine metabolism derivative.

CONCLUSIONS

UHPLC-MS/MS assays provided a metabolomic signature highly predictive of PD. These findings provide further evidence for involvement of polyamine pathways in the neurodegeneration of PD.

Inhibition of chikungunya virus replication by N-ω-Chloroacetyl-L-Ornithine in C6/36, Vero cells and human fibroblast BJ

BACKGROUND

Polyamines are involved in several cellular processes and inhibiting their synthesis affects chikungunya virus (CHIKV) replication and translation, and, therefore, reduces the quantity of infectious viral particles produced. In this study, we evaluated the inhibition of CHIKV replication by N-ω-chloroacetyl-L-ornithine (NCAO), a competitive inhibitor of ornithine decarboxylase, an enzyme which is key in the biosynthesis of polyamines (PAs).

METHODS

The cytotoxicity of NCAO was evaluated by MTT in cell culture. The inhibitory effect of CHIKV replication by NCAO was evaluated in Vero and C6/36 cells. The intracellular polyamines were quantified by HPLC in CHIKV-infected cells. We evaluated the yield of CHIKV in titres via the addition of PAs in Vero, C6/36 cells and human fibroblast BJ treated with NCAO.

RESULTS

We found that NCAO inhibits the replication of CHIKV in Vero and C6/36 cells in a dose-dependent manner, causing a decrease in the PFU/mL of at least 4 logarithms (p < 0.01) in both cell lines. Viral yields were restored by the addition of exogenous polyamines, mainly putrescine. The HPLC analyses showed that NCAO decreases the content of intracellular PAs, even though it is predominantly spermidines and spermines which are present in infected cells. Inhibition of CHIKV replication was observed in human fibroblast BJ treated with 100 μM NCAO 24 h before and 48 h after the infection at a MOI 1.

CONCLUSIONS

NCAO inhibits CHIKV replication by depleting the intracellular polyamines in Vero, C6/36 cells and human fibroblast BJ, suggesting that this compound is a possible antiviral agent for CHIKV.

Gut Microbial Metabolites on Host Immune Responses in Health and Disease

Intestinal microorganisms interact with various immune cells and are involved in gut homeostasis and immune regulation. Although many studies have discussed the roles of the microorganisms themselves, interest in the effector function of their metabolites is increasing. The metabolic processes of these molecules provide important clues to the existence and function of gut microbes. The interrelationship between metabolites and T lymphocytes in particular plays a significant role in adaptive immune functions. Our current review focuses on 3 groups of metabolites: short-chain fatty acids, bile acids metabolites, and polyamines. We collated the findings of several studies on the transformation and production of these metabolites by gut microbes and explained their immunological roles. Specifically, we summarized the reports on changes in mucosal immune homeostasis represented by the Tregs and Th17 cells balance. The relationship between specific metabolites and diseases was also analyzed through latest studies. Thus, this review highlights microbial metabolites as the hidden treasure having potential diagnostic markers and therapeutic targets through a comprehensive understanding of the gut-immune interaction.

Evaluation of biochemical composition of hulled and hull-less genotypes of pumpkin seeds grown in subtropical India

Pumpkin seeds are one of the functional foods with most potential having myriad of uses, and functioning as both edible seeds and oilseeds. Nevertheless, their utilization is restricted to the presence of a thick seed coat (hull) which subjects them to the process of decortication, increasing the farmers' expense as well as limiting their utilization as oilseeds. Therefore, in the present study, characterization of the biochemical composition of the hulled (Punjab Chappan Kadoo-1 abbreviated as PCK-1) and hull-less (PAU Magaz Kadoo-1 abbreviated as PMK-1) genotype of pumpkin seeds was undertaken to assess the nutritional differences and their efficient application; PMK-1 is a new cultivar of pumpkin released by Punjab Agricultural University in 2018. Based on the characterization, the hulled genotype of pumpkin seeds was observed to possess higher content of total soluble proteins (79.62 mg/100 g), total free amino acids (3.48 g/100 g), moisture (6.74%), fibre content (21.1 g/100 g), antioxidant potential (26.15%), polyamines (19.2 mg/100 g), sterols (387.1 mg/100 g), and specific enzymatic activity whereas the hull-less genotype was observed to possess a higher amount of minerals (4.57 g/100 g), tocopherols (15.76 mg/100 g), and oil content (36%) respectively; most of the biochemical parameters do not differ from each other at a greater fold difference except for total free amino acids and fibre, which are nearly four times and three times higher in hulled seeds in comparison to the naked seeds respectively. The two genotypes of seeds do not compete, rather do complement each other in biochemical and nutritional composition.

Good cop, bad cop: Polyamines play both sides in host immunity and viral replication

Viruses rely on host cells for energy and synthesis machinery required for genome replication and particle assembly. Due to the dependence of viruses on host cells, viruses have evolved multiple mechanisms by which they can induce metabolic changes in the host cell to suit their specific requirements. The host immune response also involves metabolic changes to be able to react to viral insult. Polyamines are small ubiquitously expressed polycations, and their metabolism is critical for viral replication and an adequate host immune response. This is due to the variety of functions that polyamines have, ranging from condensing DNA to enhancing the translation of polyproline-containing proteins through the hypusination of eIF5A. Here, we review the diverse mechanisms by which viruses exploit polyamines, as well as the mechanisms by which immune cells utilize polyamines for their functions. Furthermore, we highlight potential avenues for further study of the host-virus interface.

Endogenous Modulators of NMDA Receptor Control Dendritic Field Expansion of Cortical Neurons

Impairments of N-methyl-D-aspartate receptor (NMDAR) activity have been implicated in several neuropsychiatric disorders, with pharmacological inhibition of NMDAR-mediated currents and associated neurobehavioral changes considered as a model of schizophrenia. We analyzed the effects of brief and long-term exposure of rat cortical cultures to the most prevalent endogenous modulators of NMDAR (kynurenic acid, pregnenolone sulfate, spermidine, and zinc) on neuronal viability, stimulation-induced release of glutamate, and dendritic morphology with synaptic density. Both, glutamate release and neuronal viability studies revealed no difference between the test and control groups. No differences were also observed in the number of dendritic branching and length, or density of synaptic connections and neuronal soma size. Comparison of the extent of dendritic projections and branching patterns, however, revealed enhanced distal arborization with the expansion of the dendritic area under prolonged treatment of cultures with physiological concentrations of NMDAR modulators, with differences reaching significance in spermidine and pregnenolone sulfate tests. Measurements of the density of glutamatergic synapses showed consistency across all neuronal groups, except those treated with pregnenolone sulfate, which showed a reduction of PSD-95-positive elements. Overall, our data suggest that constitutive glutamatergic activity mediated by NMDAR controls the dendritic field expansion and can influence the integrative properties of cortical neurons.

Comparison of the Polyamine Content of Five Spring Flowers with Wheat Germ as a Rich Anti-aging Polyamine Source for Preparation of Nutraceutical Products

Polyamines prolong longevity due to their role in cell proliferation and are regarded as an essential group of anti-aging substances that reduce the risk of cardiovascular, neurological, and chronic inflammatory illnesses, as well as cancer. Because of its importance in growth and tissue regeneration, discovering polyamine-rich sources has gotten a lot of interest. Given the role of polyamines in controlling plant growth and physiological changes in the spring after cold winter stress, high polyamine concentrations in quickly growing plant tissues such as flowers, blossoms, and germs are possible. Based on this premise, five different spring flowers were selected and isolated from relevant plants, dried, and then quantified for the first time using an accurate, simple, and repeatable quantification method, liquid chromatography-tandem mass spectrometry. According to the amount of spermidine found in the samples investigated in this study, dried flower powders of Wisteria sinensis (244.18 µg/g), Lonicera caprifolium (217.28 µg/g), and Jasminum officinale (200.33 µg/g) appear to be a good source of spermidine. With additional research, W. sinensis dried flower powder is a good source of polyamines, whereas L. caprifolium and J. officinale dried flower powders are recommended as a rich source of spermidine for the preparation of natural supplements for people over the age of 30 to improve cell proliferation and anti-aging.

Synbiotics of Bifidobacterium breve MCC1274 and lactulose enhances production of tryptophan metabolites in fermented human fecal communities

Probiotics and prebiotics have beneficial effects on host physiology via metabolites from the gut microbiota in addition to their own. Here, we used a pH-controlled single-batch fermenter as a human gut microbiota model. We conducted fecal fermentation with Bifidobacterium breve MCC1274 (probiotic), lactulose (prebiotic), or a combination of both (synbiotic) to evaluate their influence on the gut environment. Fecal inoculum without the probiotic and prebiotic was used as the control. Principal coordinate analysis (PCoA), based on the composition of gut microbiota, showed a significant difference among the groups. The relative abundance of Bifidobacterium was significantly higher in the synbiotic group, compared to that in the other three treatment groups. The relative abundance of Blautia was the highest in the control group among the four groups. CE-TOFMS and LC-TOFMS showed that the number of metabolites detected in the synbiotic group was the highest (352 in total); 29 of the 310 hydrophilic metabolites and 17 of the 107 lipophilic metabolites were significantly different among the four groups in the Kruskal-Wallis test. A clustering based on 46 metabolites indicated that tryptophan-metabolites such as indole-3-lactic acid (ILA), indole-3-ethanol, and indole-3-carboxaldehyde, were included in a sub cluster composed of metabolites enriched in the synbiotic group. Spermidine, a major polyamine, was enriched in the two groups supplemented with the probiotic whereas spermine was enriched only in the synbiotic group. Not all metabolites enriched in the probiotic and/or synbiotic groups were found in the monocultures of the probiotic strain with or without the prebiotics. This implies that some of the metabolites were produced through the interaction of the fecal microbiota with the inoculated probiotic strain. Co-abundance networking analysis indicated the differences in the correlations between the relative abundance of the fecal microbiota genus and the tryptophan metabolites in each group. There was a strong correlation between ldh4 gene abundance and ILA concentration in the fecal fermentation. The copy number of ldh4 gene was significantly higher in the groups with the probiotic than that in the control group. In conclusion, synbiotics could enhance the production of signaling molecules in the gut environment. Our results provide an insight into more effective administration of probiotics at the molecular level.

P5B-ATPases in the mammalian polyamine transport system and their role in disease

Polyamines (PAs) are physiologically relevant molecules that are ubiquitous in all organisms. The vitality of PAs to the healthy functioning of a cell is due to their polycationic nature causing them to interact with a vast plethora of cellular players and partake in numerous cellular pathways. Naturally, the homeostasis of such essential molecules is tightly regulated in a strictly controlled interplay between intracellular synthesis and degradation, uptake from and secretion to the extracellular compartment, as well as intracellular trafficking. Not surprisingly, dysregulated PA homeostasis and signaling are implicated in multiple disorders, ranging from cancer to neurodegeneration; leading many to propose rectifying the PA balance as a potential therapeutic strategy. Despite being well characterized in bacteria, fungi and plants, the molecular identity and properties of the PA transporters in animals are poorly understood. This review brings together the current knowledge of the cellular function of the mammalian PA transport system (PTS). We will focus on the role of P5B-ATPases ATP13A2-5 which are PA transporters in the endosomal system that have emerged as key players in cellular PA uptake and organelle homeostasis. We will discuss recent breakthroughs on their biochemical and structural properties as well as their implications for disease and therapy.

Over-expression of spermidine synthase 2 (SlSPDS2) in tomato plants improves saline-alkali stress tolerance by increasing endogenous polyamines content to regulate antioxidant enzyme system and ionic homeostasis

Endogenous spermidine can improve the resistance of plants to saline-alkali stress. SlSPDS1 and SlSPDS2 are the main spermidine synthase (SPDS) genes in tomatoes. In comparison with SlSPDS1, SlSPDS2 plays an important role in wild-type tomato seedling under saline-alkali stress. However, limited research has focused on the role of SlSPDS2 in saline-alkali stress. Wild-type (WT) and SPDS gene (SlSPDS2) transgenic over-expression tomato seedlings were used to explore the function of endogenous spermidine on the saline-alkali resistance of tomato seedlings. The results show that SlSPDS2 overexpression under normal conditions and saline-alkali stress increased the content of endogenous free polyamines and the expression levels of polyamine synthesis-related genes in tomato seedlings. Under saline-alkali stress, SlSPDS2 overexpression significantly reduced Na+/K+ ratio, relative electrical conductivity, O2·-, H2O2, and malondialdehyde content, increased Seedling index, relative water content, antioxidant enzyme activities (peroxidase, superoxide dismutase, and catalase), and the contents of proline and soluble sugar in tomato leaf, and mitigated the adverse effect of saline-alkali stress on tomato seedlings. In summary, the overexpression of SlSPDS2 tomato seedlings regulated the ionic homeostasis, antioxidant enzyme system, and osmotic regulatory substances of tomato seedlings living in saline-alkali environment by increasing endogenous free polyamine content, thereby improving the resistance of tomato seedlings against saline-alkali stress.

Ornithine decarboxylase regulates putrescine-related metabolism and pollen development in Atropa belladonna

Polyamines, including putrescine, spermidine, and spermine, play critical roles in cell physiology by different forms. As a rate-limiting enzyme that converts ornithine to putrescine, ornithine decarboxylase (ODC, EC 1.1.1.37) has been studied in detail in animals and microorganisms, but its specific functions are poorly understood in plants. In this study, the metabolic and developmental roles of the ODC gene were studied through RNAi-mediated suppression of the ODC gene (AbODC) in A. belladonna. Suppression of AbODC reduced the production of precursors of medicinal tropane alkaloids, including putrescine and N-methylputrescine, as well as hyoscyamine and scopolamine. In AbODC-RNAi roots, the production of putrescine and spermidine in free form was reduced, but in the AbODC-RNAi leaves, the content of free polyamines was not altered. In the roots/leaves of AbODC-RNAi plants, the production of conjugated and bound polyamines was reduced. In addition, suppression of the ODC gene resulted in reduction of polyamines and pollen sterility in AbODC-RNAi flowers. In floral organs, GUS-staining results indicated that AbODC was domainantly expressed in pollen. In summary, ornithine decarboxylase not only plays a key role in regulating the biosynthesis of diverse forms of polyamines and medicinal tropane alkaloids, but also participates in pollen development.

Pseudomonas aeruginosa utilizes the host-derived polyamine spermidine to facilitate antimicrobial tolerance

Pseudomonas aeruginosa undergoes diversification during infection of the cystic fibrosis (CF) lung. Understanding these changes requires model systems that capture the complexity of the CF lung environment. We previously identified loss-of-function mutations in the 2-component regulatory system sensor kinase gene pmrB in P. aeruginosa from CF lung infections and from experimental infection of mice. Here, we demonstrate that, while such mutations lowered in vitro minimum inhibitory concentrations for multiple antimicrobial classes, this was not reflected in increased antibiotic susceptibility in vivo. Loss of PmrB impaired aminoarabinose modification of LPS, increasing the negative charge of the outer membrane and promoting uptake of cationic antimicrobials. However, in vivo, this could be offset by increased membrane binding of other positively charged molecules present in lungs. The polyamine spermidine readily coated the surface of PmrB-deficient P. aeruginosa, reducing susceptibility to antibiotics that rely on charge differences to bind the outer membrane and increasing biofilm formation. Spermidine was elevated in lungs during P. aeruginosa infection in mice and during episodes of antimicrobial treatment in people with CF. These findings highlight the need to study antimicrobial resistance under clinically relevant environmental conditions. Microbial mutations carrying fitness costs in vitro may be advantageous during infection, where host resources can be utilized.

via modulating polyamines profile

Manganese (Mn) toxicity in soil is a widely observed phenomenon, which seriously restricts growth, quality, and yield of various crops and fruits including apples. However, mechanisms underlying the regulation of polyamines (PAs) by brassinosteroids (BRs) to improve tolerance to Mn stress are still unclear. In this study, we investigated the effects of 2,4-epibrassinolide (EBL; a BR) on the expression of genes involved in BR signaling pathway, Mn accumulation, PAs-mediated responses (PA precursor levels, metabolic enzymes, and genes), and growth parameters in Mn-stressed Malus robusta Rehd. EBL application significantly modulated the expressions of genes related to BR signaling (MdBRI, MdBSK, etc.) and reduced Mn accumulation, along with improving the rate of increase in root length and plant height, relative water content, chlorophyll content, maximum photochemical efficiency of PSII (Fv/Fm), and actual photochemical efficiency (Φ_PSII) and decreasing electrical conductivity. Furthermore, EBL application significantly reduced putrescine (Put) accumulation and increased spermine (Spm) content and (Spd + Spm)/Put ratio. EBL weakened ornithine (Orn) pathway, decreased ornithine decarboxylase (ODC) activity, and increased biosynthesis of Spm from Put via elevating the PA oxidase (PAO) activity and expression of MdSPDS, MdSPMS, and MdPAO. The trends for free, PS-conjugated, and PIS-bound PAs were similar to that of total PAs, except that no significant change was observed in free Spm, PS-conjugated Spd, and Spm, as well as PIS-bound Spd. This study revealed that BR-regulated PAs help in mitigating Mn toxicity and clarified the mechanisms of regulation of PAs by BRs in apple trees.

The role of ethylene signalling in the regulation of salt stress response in mature tomato fruits: Metabolism of antioxidants and polyamines

Salt stress-induced ethylene (ET) can influence the defence responses of plants that can be dependent on plant organs. In this work, the effects of salt stress evoked by 75 mM NaCl treatment were measured in fruits of wild-type (WT) and ET receptor-mutant Never ripe (Nr) tomato. Salt stress reduced the weight and size of fruits both in WT and Nr, which proved to be more pronounced in mutants. In addition, significantly higher H₂O₂ levels and lipid peroxidation were measured after the salt treatment in Nr as compared to the untreated control than in WT. ET regulated the key antioxidant enzymes, especially ascorbate peroxidase (APX), in WT but in the mutant fruits the activity of APX did not change and the superoxide dismutase and catalase activities were downregulated compared to untreated controls after salt treatment contributing to a higher degree of oxidative stress in Nr fruits. The dependency of PA metabolism on the active ET signalling was investigated for the first time in fruits of Nr mutants under salt stress. 75 mM NaCl enhanced the accumulation of spermine in WT fruits, which was not observed in Nr, but levels of putrescine and spermidine were elevated by salt stress in these tissues. Moreover, the catabolism of PAs was much stronger under high salinity in Nr fruits contributing to higher oxidative stress, which was only partially alleviated by the increased total and reduced ascorbate and glutathione pool. We can conclude that ET-mediated signalling plays a crucial role in the regulation of salt-induced oxidative stress and PA levels in tomato fruits at the mature stage.

The divergent genome of Scorpion Group 1 (SG1) intracellular bacterium from the venom glands of Vaejovis smithi (Scorpiones: Vaejovidae)

Scorpions were among the first animals on land around 430 million years ago. Like many arachnids, scorpions have evolved complex venoms used to paralyze their prey and for self-defense. Here we sequenced and analyzed the metagenomic DNA from venom glands from Vaejovis smithi scorpions. A metagenome-assembled genome (MAG) of 624,025 bp was obtained corresponding to the previously reported Scorpion Group 1 (SG1). The SG1 genome from venom glands had a low GC content (25.8%) characteristic of reduced genomes, many hypothetical genes and genes from the reported minimal set of bacterial genes. Phylogenomic reconstructions placed the uncultured SG1 distant from other reported bacteria constituting a taxonomic novelty. By PCR we detected SG1 in all tested venom glands from 30 independent individuals. Microscopically, we observed SG1 inside epithelial cells from the venom glands using FISH and its presence in scorpion embryos suggested that SG1 is transferred from mother to offspring.

Phenylbutyrate modulates polyamine acetylase and ameliorates Snyder-Robinson syndrome in a Drosophila model and patient cells

Polyamine dysregulation plays key roles in a broad range of human diseases from cancer to neurodegeneration. Snyder-Robinson syndrome (SRS) is the first known genetic disorder of the polyamine pathway, caused by X-linked recessive loss-of-function mutations in spermine synthase. In the Drosophila SRS model, altered spermidine/spermine balance has been associated with increased generation of ROS and aldehydes, consistent with elevated spermidine catabolism. These toxic byproducts cause mitochondrial and lysosomal dysfunction, which are also observed in cells from SRS patients. No efficient therapy is available. We explored the biochemical mechanism and discovered acetyl-CoA reduction and altered protein acetylation as potentially novel pathomechanisms of SRS. We repurposed the FDA-approved drug phenylbutyrate (PBA) to treat SRS using an in vivo Drosophila model and patient fibroblast cell models. PBA treatment significantly restored the function of mitochondria and autolysosomes and extended life span in vivo in the Drosophila SRS model. Treating fibroblasts of patients with SRS with PBA ameliorated autolysosome dysfunction. We further explored the mechanism of drug action and found that PBA downregulates the first and rate-limiting spermidine catabolic enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1), reduces the production of toxic metabolites, and inhibits the reduction of the substrate acetyl-CoA. Taken together, we revealed PBA as a potential modulator of SAT1 and acetyl-CoA levels and propose PBA as a therapy for SRS and potentially other polyamine dysregulation-related diseases.

The role of Astragalus polysaccharides in promoting IEC-6 cell migration from polyamine-mediated Ca2+ regulation

Astragalus polysaccharide (APS) has a protective effect on injured intestinal mucosa by promoting intestinal cell migration, but the specific mechanism is unclear. The polyamine-mediated calcium signaling pathway is an important mechanism of cell migration, generally, and we tested the hypothesis that APS can protect damaged intestinal mucosa through the polyamine-mediated calcium signaling pathway. High-performance liquid chromatography (HPLC), infrared chromatography, cell scratch test, Western blot, co-immunoprecipitation, polyamine inhibitor (DFMO), si-Cav1, RhoA inhibitor (Rhosin) and Rac1 inhibitor (NSC23766) were used to detect the pharmacodynamic of APS. The results show that APS can promote cell migration. In addition, APS increased the formations of RhoA/TRPC1, Cav1/TRPC1, and Rac1/PLCγ-1 complexes as well as the expressions of TRPC1, PLCγ-1, RhoA, Cav1, and Rac1, and it reversed the inhibitory effect of DFMO on the above factors. APS also reversed the inhibitory effect of si-Cav1 on Cav1 expression, cytoplasmic Ca²⁺ concentrations ([Ca²⁺]cyt), and cell migration. Moreover, APS removed the inhibition of NSC23766 and Rhosin on [Ca²⁺]cyt and cell migration. In vivo study, the water extract of Astragalus membranaceus (WEA) (15 g/kg) reduced the indomethacin-induced injury of intestinal mucosa as well. These observations suggest that APS can treat gastrointestinal mucosal injury through the polyamine calcium signaling pathway.

Metagenomes of polyamine-transforming bacterioplankton along a nearshore-open ocean transect

Short-chained aliphatic polyamines (PAs) have recently been recognized as an important carbon, nitrogen, and/or energy source for marine bacterioplankton. To study the genes and taxa involved in the transformations of different PA compounds and their potential variations among marine systems, we collected surface bacterioplankton from nearshore, offshore, and open ocean stations in the Gulf of Mexico and examined their metagenomic responses to additions of single PA model compounds (putrescine, spermidine, or spermine). Genes affiliated with PA uptake and all three known PA degradation pathways, i.e., transamination, γ-glutamylation, and spermidine cleavage, were significantly enriched in most PA-treated metagenomes. In addition, identified PA-transforming taxa were mostly the alpha and gamma classes of Proteobacteria, with less important contributions from members of Betaproteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Planctomycetes. These findings suggest that PA transformations are ubiquitous, have diverse pathways, and are carried out by a broad range of the bacterioplankton taxa in the Gulf of Mexico. Identified PA-transforming bacterial genes and taxa were different among nearshore, offshore, and open ocean sites, but were little different among individual compound-amended metagenomes at any specific site. These observations further indicate that PA-transforming taxa and genes are site-specific and with high similarities among PA compounds.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-021-00114-x.

Polyamine-metabolizing enzymes are activated to promote the proper assembly of rice stripe mosaic virus in insect vectors

Both viruses and host cells compete for intracellular polyamines for efficient propagation. Currently, how the key polyamine-metabolizing enzymes, including ornithine decarboxylase 1 (ODC1) and its antizyme 1 (OAZ1), are activated to co-ordinate viral propagation and polyamine biosynthesis remains unknown. Here, we report that the matrix protein of rice stripe mosaic virus (RSMV), a cytorhabdovirus, directly hijacks OAZ1 to ensure the proper assembly of rigid bacilliform non-enveloped virions in leafhopper vector. Viral matrix protein effectively competes with ODC1 to bind to OAZ1, and thus, the ability of OAZ1 to target and mediate the degradation of ODC1 is significantly inhibited during viral propagation, which finally promotes polyamines production. Thus, OAZ1 and ODC1 are activated to synergistically promote viral persistent propagation and polyamine biosynthesis in viruliferous vectors. Our data suggest that it is a novel mechanism for rhabdovirus to exploit OAZ1 for facilitating viral assembly.