bims-polyam 2019-09-15 papers

on Polyamines

Issue of 2019–09–15
sixteen papers selected by
Sebastian J. Hofer, University of Graz and Alexander Ivanov, Engelhardt Institute of Molecular Biology

Association between plasma diacetylspermine and tumor spermine synthase with outcome in triple negative breast cancer.
Polyamine biosynthesis in Xenopus laevis: the xlAZIN2/xlODC2 gene encodes a lysine/ornithine decarboxylase.
Overexpression of the arginine decarboxylase gene promotes the symbiotic interaction Medicago truncatula-Sinorhizobium meliloti and induces the accumulation of proline and spermine in nodules under salt stress conditions.
Putrescine Is an Intraspecies and Interkingdom Cell-Cell Communication Signal Modulating the Virulence of Dickeya zeae.
The investigation of structure-activity relationship of polyamine-targeted synthetic compounds from different chemical groups.
Lampropedia aestuarii sp. nov., isolated from the estuary of a freshwater river.
Crosstalk among polyamines, phytohormones, hydrogen peroxide, and phenylethanoid glycosides responses in Scrophularia striata to Cd stress.
Lipid nanoparticle-targeted mRNA therapy as a treatment for the inherited metabolic liver disorder arginase deficiency.
Counterion-Dependent Mechanisms of DNA Origami Nanostructure Stabilization Revealed by Atomistic Molecular Simulation.
Establishment of ornithine transcarbamylase deficiency-derived primary human hepatocyte with hepatic functions.
Putrescine mitigates intestinal atrophy through suppressing inflammatory response in weanling piglets.
Agmatine reverses ethanol consumption in rats: Evidences for an interaction with imidazoline receptors.
Spermidine ameliorates liver ischaemia-reperfusion injury through the regulation of autophagy by the AMPK-mTOR-ULK1 signalling pathway.
Methionine metabolism in health and cancer: a nexus of diet and precision medicine.
Antidepressant-like effects of agmatine and NOS inhibitors in chronic unpredictable mild stress model of depression in rats: The involvement of NLRP inflammasomes.
MCU Up-regulation contributes to myocardial ischemia-reperfusion Injury through calpain/OPA-1-mediated mitochondrial fusion/mitophagy Inhibition.

J Natl Cancer Inst. 2019 Sep 10. pii: djz182. [Epub ahead of print]

Association between plasma diacetylspermine and tumor spermine synthase with outcome in triple negative breast cancer.

Johannes F Fahrmann, Jody Vykoukal, Alia Fleury, Satyendra Tripathi, Jennifer B Dennison, Eunice Murage, Peng Wang, Chuan-Yih Yu, Michela Capello, Chad J Creighton, Kim-Anh Do, James P Long, Ehsan Irajizad, Christine Peterson, Hiroyuki Katayama, Mary L Disis, Banu Arun, Samir Hanash.

   BACKGROUND: MYC is an oncogenic driver of development and progression in triple-negative breast cancer (TNBC). Ornithine decarboxylase, the rate-limiting enzyme in polyamine metabolism, is a transcriptional target of MYC. We therefore hypothesized that a plasma polyamine signature may be predictive of TNBC development and progression.
METHODS: Using liquid chromatography mass spectrometry, polyamine levels were determined in plasma samples from newly diagnosed patients with TNBC (n = 87) and cancer-free controls (n = 115). Findings were validated in plasma samples from an independent prospective cohort of 54 TNBC, 55 ER-/PR-/HER2+, and 73 ER+ cases, and 30 cancer-free controls. Gene expression data and clinical data for 921 and 2359 breast cancer tumors were obtained from The Cancer Genome Atlas (TCGA) repository and the Oncomine database, respectively. Relationships between plasma diacetylspermine (DAS) and tumor spermine synthase (SMS) mRNA expression with metastasis free survival and overall survival were determined using Cox proportional hazard models; Fisher's exact tests were used to assess risk of distant metastasis in relation to tumor SMS mRNA expression.
RESULTS: An increase in plasma DAS, a catabolic product of spermine mediated through SMS, was observed in the TNBC subtype of breast cancer. Plasma levels of DAS in TNBC associated with increased risk of metastasis (plasma DAS value ≥ 1.16 HR= 3.06, 95% CI = 1.15-8.13, 2-sided P = .03). SMS mRNA expression in TNBC tumor tissue was also found to be predictive of poor overall survival (top 25th percentile HR = 2.06, 95% CI = 1.04-4.08, 1-sided P= .04) and increased risk of distant metastasis in TNBC (comparison of lowest SMS quartile (reference) to highest SMS quartile Relative Risk= 1.90, 95% CI = 0.97-4.06, 1-sided Fisher's exact test P=.03).
CONCLUSION: Metabolomic profiling identified plasma DAS as a predictive marker for TNBC progression and metastasis.

Keywords:  Biomarker; Metastasis; Prognosis; Triple-Negative Breast Cancer

DOI:  https://doi.org/10.1093/jnci/djz182
PLoS One. 2019 ;14(9): e0218500

Polyamine biosynthesis in Xenopus laevis: the xlAZIN2/xlODC2 gene encodes a lysine/ornithine decarboxylase.

Ana Lambertos, Rafael Peñafiel.

Ornithine decarboxylase (ODC) is a key enzyme in the biosynthesis of polyamines, organic cations that are implicated in many cellular processes. The enzyme is regulated at the post-translational level by an unusual system that includes antizymes (AZs) and antizyme inhibitors (AZINs). Most studies on this complex regulatory mechanism have been focused on human and rodent cells, showing that AZINs (AZIN1 and AZIN2) are homologues of ODC but devoid of enzymatic activity. Little is known about Xenopus ODC and its paralogues, in spite of the relevance of Xenopus as a model organism for biomedical research. We have used the information existing in different genomic databases to compare the functional properties of the amphibian ODC1, AZIN1 and AZIN2/ODC2, by means of transient transfection experiments of HEK293T cells. Whereas the properties of xlODC1 and xlAZIN1 were similar to those reported for their mammalian orthologues, the former catalyzing the decarboxylation of L-ornithine preferentially to that of L-lysine, xlAZIN2/xlODC2 showed important differences with respect to human and mouse AZIN2. xlAZIN2 did not behave as an antizyme inhibitor, but it rather acts as an authentic decarboxylase forming cadaverine, due to its higher affinity to L-lysine than to L-ornithine as substrate; so, in accordance with this, it should be named as lysine decarboxylase (LDC) or lysine/ornithine decarboxylase (LODC). In addition, AZ1 stimulated the degradation of xlAZIN2 by the proteasome, but the removal of the 21 amino acid C-terminal tail, with a sequence quite different to that of mouse or human ODC, made the protein resistant to degradation. Collectively, our results indicate that in Xenopus there is only one antizyme inhibitor (xlAZIN1) and two decarboxylases, xlODC1 and xlLDC, with clear preferences for L-ornithine and L-lysine, respectively.

DOI: https://doi.org/10.1371/journal.pone.0218500
J Plant Physiol. 2019 Aug 27. pii: S0176-1617(19)30151-8. [Epub ahead of print]241 153034

Overexpression of the arginine decarboxylase gene promotes the symbiotic interaction Medicago truncatula-Sinorhizobium meliloti and induces the accumulation of proline and spermine in nodules under salt stress conditions.

Javier Hidalgo-Castellanos, Ana Sofia Duque, Alvaro Burgueño, José A Herrera-Cervera, Pedro Fevereiro, Miguel López-Gómez.

  Legumes have the capacity to fix nitrogen in symbiosis with soil bacteria known as rhizobia by the formation of root nodules. However, nitrogen fixation is highly sensitive to soil salinity with a concomitant reduction of the plant yield and soil fertilization. Polycationic aliphatic amines known as polyamines (PAs) have been shown to be involved in the response to a variety of stresses in plants including soil salinity. Therefore, the generation of transgenic plants overexpressing genes involved in PA biosynthesis have been proposed as a promising tool to improve salt stress tolerance in plants. In this work we tested whether the modulation of PAs in transgenic Medicago truncatula plants was advantageous for the symbiotic interaction with Sinorhizobium meliloti under salt stress conditions, when compared to wild type plants. Consequently, we characterized the symbiotic response to salt stress of the homozygous M. truncatula plant line L-108, constitutively expressing the oat adc gene, coding for the PA biosynthetic enzyme arginine decarboxylase, involved in PAs biosynthesis. In a nodulation kinetic assay, nodule number incremented in L-108 plants under salt stress. In addition, these plants at vegetative stage showed higher nitrogenase and nodule biomass and, under salt stress, accumulated proline (Pro) and spermine (Spm) in nodules, while in wt plants, the accumulation of glutamic acid (Glu), γ-amino butyric acid (GABA) and 1-aminocyclopropane carboxylic acid (ACC) (the ethylene (ET) precursor) were the metabolites involved in the salt stress response. Therefore, overexpression of oat adc gene favours the symbiotic interaction between plants of M. truncatula L-108 and S. meliloti under salt stress and the accumulation of Pro and Spm, seems to be the molecules involved in salt stress tolerance.

Keywords:  Medicago truncatula; Nitrogen fixation; Polyamines; Salt stress; Symbiosis

DOI:  https://doi.org/10.1016/j.jplph.2019.153034
Front Microbiol. 2019 ;10 1950

Putrescine Is an Intraspecies and Interkingdom Cell-Cell Communication Signal Modulating the Virulence of Dickeya zeae.

Zurong Shi, Qingwei Wang, Yasheng Li, Zhibing Liang, Linghui Xu, Jianuan Zhou, Zining Cui, Lian-Hui Zhang.

  The infections caused by Dickeya zeae become a severe problem in recent years, but the regulatory mechanisms that govern the bacterial virulence remain to be fragmental. Here we report the investigation of potential involvement of polyamines in regulation of D. zeae virulence. We showed that null mutation of speA encoding arginine decarboxylase dramatically decreased the bacterial swimming motility, swarming motility and biofilm formation, and exogenous addition of putrescine effectively rescues the defective phenotypes of D. zeae. HPLC and mass spectrometry analysis validated that speA was essential for production of putrescine in D. zeae. In addition, we demonstrated that D. zeae EC1 could detect and response to putrescine molecules produced by itself or from host plant through specific transporters. Among the two transporters identified, the one represented by PotF played a dominated role over the other represented by PlaP in modulation of putrescine-dependent biological functions. Furthermore, we provided evidence that putrescine signal is critical for D. zeae EC1 bacterial invasion and virulence against rice seeds. Our data depict a novel function of putrescine signal in pathogen-host communication and in modulation of the virulence of an important plant bacterial pathogen.

Keywords:  cell-cell signaling; pathogen-host communication; polyamine; putrescine; regulatory elements; regulatory network

DOI:  https://doi.org/10.3389/fmicb.2019.01950
Amino Acids. 2019 Sep 13.

The investigation of structure-activity relationship of polyamine-targeted synthetic compounds from different chemical groups.

Sergey P Syatkin, Ekaterina V Neborak, Andrei I Khlebnikov, Marina V Komarova, Natalia A Shevkun, Eduard G Kravtsov, Mikhail L Blagonravov, Enzo Agostinelli.

  The polyamine (PA) metabolism is involved in cell proliferation and differentiation. Increased cellular PA levels are observed in different types of cancers. Products of PA oxidation induce apoptosis in cancer cells. These observations open a perspective to exploit the enzymes of PA catabolism as a target for anticancer drug design. The substances capable to enhance PA oxidation may become potential anticancer agents. The goal of our study was to explore how the mode of ligand binding with a PA catabolic enzyme is associated with its stimulatory or inhibitory effect upon PA oxidation. Murine N1-acetylpolyamine oxidase (5LFO) crystalline structure was used for molecular docking with ligands of various chemical structures. In vitro experiments were carried out to evaluate the action of the tested compounds upon PA oxidative deamination in a cell-free test system from rat liver. Two amino acid residues (Aps211 and Tyr204) in the structure of 5LFO were found to be significant for binding with the tested compounds. 19 out of 51 screened compounds were activators and 17 were inhibitors of oxidative deamination of PA. Taken together, these results enabled to construct a recognition model with characteristic descriptors depicting activators and inhibitors. The general tendency indicated that a strong interaction with Asp211 or Tyr204 was rather typical for activators. The understanding of how the structure determines the binding mode of compounds with PA catabolic enzyme may help in explanation of their structure-activity relationship and thus promote structure-based drug design.

Keywords:  Molecular docking; Polyamine catabolism; Polyamine-targeted agents; Polyamines; Structure–activity relationship

DOI:  https://doi.org/10.1007/s00726-019-02778-3
Int J Syst Evol Microbiol. 2019 Sep 13.

Lampropedia aestuarii sp. nov., isolated from the estuary of a freshwater river.

Yi-Ting Zhao, Ya-Ping Li, Wei Xiao, Wei-Hong Liu, Xiao-Long Cui, Yong-Xia Wang.

  A Gram-stain-negative, strictly aerobic, catalase-positive and oxidase-positive bacterium, designated strain YIM MLB12T, was isolated from estuary sediment sampled at Maliao River where it flows into a plateau lake (Dianchi) in Yunnan, south-west PR China. Cells were non-motile and rod-shaped. Growth was observed at 15-35 °C (optimum, 25-30 °C), pH 6.0-10.0 (optimum, pH 7.0-8.0) and in the presence of 0-7 % (w/v) NaCl (optimum, 0.5-2 %). Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM MLB12T formed a tight phylogenic lineage with members of the genus Lampropedia and was closely related to 'Lampropedia puyangensis' 2-bin with 98.3 % sequence similarity and had low similarities to the type strains of Lampropediahyalina ATCC 11041T (96 %) and Lampropedia cohaerens CT6T (95.5 %). Average nucleotide identity and in silico DNA-DNA hybridization values between strain YIM MLB12T and 'L. puyangensis' KCTC 32235 were 76.5 and 22.6 %, respectively. Strain YIM MLB12T contained ubiquinone-8 as the major quinone. The predominant cellular fatty acids were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C16 : 0, C10 : 0 3-OH, summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c), C12 : 0 3-OH and C14 : 0. The polar lipid profile of strain YIM MLB12T was composed predominantly of diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. The major polyamine was spermidine. The genomic DNA G+C content of strain YIM MLB12T was 56.8 mol%. Based on its genotypic and chemotaxonomic features and results of phenotypic analyses, strain YIM MLB12T represents a novel species of the genus Lampropedia, for which the name Lampropediaaestuarii sp. nov. is proposed. The type strain is YIM MLB12T (=KCTC 42886T=CGMCC 1.17071T).

Keywords:  Lampropedia aestuarii sp. nov.; estuary; polyphasic taxonomy

DOI:  https://doi.org/10.1099/ijsem.0.003710
Plant Physiol Biochem. 2019 Aug 29. pii: S0981-9428(19)30334-1. [Epub ahead of print]143 129-141

Crosstalk among polyamines, phytohormones, hydrogen peroxide, and phenylethanoid glycosides responses in Scrophularia striata to Cd stress.

Elham Sadat Beshamgan, Mohsen Sharifi, Fatemeh Zarinkamar.

  Plants respond to Cadmium (Cd) as a hazardous heavy metal through various mechanisms depending on their available metabolite resources. In this research, the physiological and signaling pathways mediating the responses to Cd stress in Scrophularia striata seedlings were characterized after they were exposed to different Cd concentrations at different time periods. The results showed that the polyamines (PAs), Abscisic acid (ABA) and hydrogen peroxide (H2O2) contents were significantly enhanced at 48 h. Moreover, the enzyme activity of phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) as regulator enzymes in the phenylpropanoid pathway was increased, related to the reinforcement of phenolic compounds such as phenylethanoid glycosides (as a special compound of this plant). This metabolic profiling indicates that the signal transduction of Cd stress increased the activity of different enzymes (PAL and TAL) by regulating the PAs metabolism, the modulation of ABA, and the H2O2 content. As a result, it caused the accumulation of phenolic compounds, especially echinacoside and acteoside, both of which are required to improve the response of Cd stress in S. striata.

Keywords:  Acteoside; Cd stress; Echinacoside; Phenylethanoid glycosides; Polyamine; Scrophularia striata

DOI:  https://doi.org/10.1016/j.plaphy.2019.08.028
Proc Natl Acad Sci U S A. 2019 Sep 09. pii: 201906182. [Epub ahead of print]

Lipid nanoparticle-targeted mRNA therapy as a treatment for the inherited metabolic liver disorder arginase deficiency.

Brian Truong, Gabriella Allegri, Xiao-Bo Liu, Kristine E Burke, Xuling Zhu, Stephen D Cederbaum, Johannes Häberle, Paolo G V Martini, Gerald S Lipshutz.

  Arginase deficiency is caused by biallelic mutations in arginase 1 (ARG1), the final step of the urea cycle, and results biochemically in hyperargininemia and the presence of guanidino compounds, while it is clinically notable for developmental delays, spastic diplegia, psychomotor function loss, and (uncommonly) death. There is currently no completely effective medical treatment available. While preclinical strategies have been demonstrated, disadvantages with viral-based episomal-expressing gene therapy vectors include the risk of insertional mutagenesis and limited efficacy due to hepatocellular division. Recent advances in messenger RNA (mRNA) codon optimization, synthesis, and encapsulation within biodegradable liver-targeted lipid nanoparticles (LNPs) have potentially enabled a new generation of safer, albeit temporary, treatments to restore liver metabolic function in patients with urea cycle disorders, including ARG1 deficiency. In this study, we applied such technologies to successfully treat an ARG1-deficient murine model. Mice were administered LNPs encapsulating human codon-optimized ARG1 mRNA every 3 d. Mice demonstrated 100% survival with no signs of hyperammonemia or weight loss to beyond 11 wk, compared with controls that perished by day 22. Plasma ammonia, arginine, and glutamine demonstrated good control without elevation of guanidinoacetic acid, a guanidino compound. Evidence of urea cycle activity restoration was demonstrated by the ability to fully metabolize an ammonium challenge and by achieving near-normal ureagenesis; liver arginase activity achieved 54% of wild type. Biochemical and microscopic data showed no evidence of hepatotoxicity. These results suggest that delivery of ARG1 mRNA by liver-targeted nanoparticles may be a viable gene-based therapeutic for the treatment of arginase deficiency.

Keywords:  arginase deficiency; hyperargininemia; lipid nanoparticle; mRNA; ureagenesis

DOI:  https://doi.org/10.1073/pnas.1906182116
ACS Nano. 2019 Sep 10.

Counterion-Dependent Mechanisms of DNA Origami Nanostructure Stabilization Revealed by Atomistic Molecular Simulation.

Job Roodhuizen, Philip Hendrikx, Peter A J Hilbers, Tom de Greef, Albert J Markvoort.

The DNA origami technique has proven to have tremendous potential for therapeutic and diagnostic applications like drug delivery, but the relatively low concentrations of cations in physiological fluids cause destabilization and degradation of DNA origami constructs preventing in vivo applications. To reveal the mechanisms behind DNA origami stabilization by cations, we performed atomistic molecular dynamics simulations of a DNA origami rectangle in aqueous solvent with varying concentrations of magnesium and sodium, as well as polyamines like oligolysine and spermine. We explored the binding of these ions to DNA origami in detail and found that the mechanism of stabilization differs between ion types considerably. While sodium binds weakly and quickly exchanges with the solvent, magnesium and spermine bind close to the origami with spermine also located in between helices, stabilizing the crossovers characteristic for DNA origami and reducing repulsion of parallel helices. In contrast, oligolysine of length ten prevents helix repulsion by binding to adjacent helices with its flexible side chains, spanning the gap between the helices. Shorter oligolysine molecules with four subunits are weak stabilizers as they lack both the ability to connect helices and to prevent helix repulsion. This work thus shows how the binding modes of ions influence stabilization of DNA origami nanostructures on a molecular level.

DOI: https://doi.org/10.1021/acsnano.9b05650
Exp Cell Res. 2019 Sep 09. pii: S0014-4827(19)30483-5. [Epub ahead of print] 111621

Establishment of ornithine transcarbamylase deficiency-derived primary human hepatocyte with hepatic functions.

Shan Su, Cristina Di Poto, Alexander H Kroemer, Wanxing Cui, Rabindra Roy, Xuefeng Liu, Habtom W Ressom.

  A long-term hepatocyte culture maintaining liver-specific functions is very essential for both basic research and the development of bioartificial liver devices in clinical application. However, primary hepatocytes rapidly lose their proliferation and hepatic functions over a few days in culture. This work is to establish an ornithine transcarbamylase deficiency (OTCD) patient-derived primary human hepatocyte (OTCD-PHH) culture with hepatic functions for providing an in vitro cell model. Liver tissue from an infant with OTCD was dispersed into single cells. The cells were cultured using conditional reprogramming. To characterize the cells, we assessed activities and mRNA expression of CYP3A4, 1A1, 2C9, as well as albumin and urea secretion. We found that the OCTD-PHH can be subpassaged for more than 15 passages. The cells do not express mRNA of fibroblast-specific maker, whereas they highly express markers of epithelial cells and hepatocytes. In addition, the OTCD-PHH retain native CYP3A4, 1A1, 2C9 activities and albumin secretion function at early passages. The OTCD-PHH at passages 2, 6, 9 and 13 have identical DNA fingerprint as the original tissue. Furthermore, under 3D culture environment, low urea production and hepatocyte marker staining of the OTCD-PHH were detected. The established OTCD-PHH maintain liver-specific functions at early passages and can be long-term cultured in vitro. We believe the established long-term OTCD-PHH culture is highly relevant to study liver diseases, particularly in infants with OTCD.

Keywords:  CYP450 activity; Long-term culture; Ornithine transcarbamylase deficiency (OTCD); Primary human hepatocyte (PHH)

DOI:  https://doi.org/10.1016/j.yexcr.2019.111621
J Anim Sci Biotechnol. 2019 ;10 69

Putrescine mitigates intestinal atrophy through suppressing inflammatory response in weanling piglets.

Bangmin Liu, Xianren Jiang, Long Cai, Xuemei Zhao, Zhaolai Dai, Guoyao Wu, Xilong Li.

   Background: Polyamines are essential for cell growth and beneficial for intestinal maturation. To evaluate the effects of putrescine on alleviating intestinal atrophy and underlying molecular mechanisms, both in vivo feeding trial and in vitro cell culture were conducted. Weanling pigs were fed a diet supplemented with 0, 0.1%, 0.2% or 0.3% putrescine dihydrochloride, whereas porcine intestinal epithelial cells (IPEC-J2) were challenged with lipopolysaccharide (LPS) in the presence of 200 μmol/L putrescine.
Results: Dietary supplementation with 0.2% putrescine dihydrochloride decreased the incidence of diarrhea with an improvement in intestinal integrity. Inhibition of ornithine decarboxylase activity decreased the proliferation and migration of IPEC-J2 cells, and this effect was alleviated by the supplementation with putrescine. The phosphorylation of extracellular signal regulated kinase and focal adhesion kinase was enhanced by putrescine. LPS increased the expression of inflammatory cytokines [tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and IL-8], and inhibited cell proliferation and migration in IPEC-J2 cells. Adding exogenous putrescine suppressed the expression of TNF-α, IL-6 and IL-8, and recovered cell migration and proliferation in LPS-treated IPEC-J2 cells. Dietary putrescine supplementation also reduced the mRNA levels of TNF-α, IL-6 and IL-8 and their upstream regulator nuclear receptor kappa B p65 subunit in the jejunal mucosa of piglets.
Conclusions: Dietary supplementation with putrescine mitigated mucosal atrophy in weanling piglets through improving anti-inflammatory function and suppressing inflammatory response. Our results have important implications for nutritional management of intestinal integrity and health in weanling piglets and other neonates.

Keywords:  Cell migration; Cell proliferation; Intestinal atrophy; Mucosal immune response; Putrescine; Weaning stress

DOI:  https://doi.org/10.1186/s40104-019-0379-9
Pharmacol Biochem Behav. 2019 Sep 04. pii: S0091-3057(19)30160-1. [Epub ahead of print] 172779

Agmatine reverses ethanol consumption in rats: Evidences for an interaction with imidazoline receptors.

Brijesh G Taksande, Shreesha Nambiar, Shardha Patil, Milind J Umekar, Manish M Aglawe, Nandkishor R Kotagale.

  Alcohol is one of the most widely abused recreational drugs, largely linked with serious health and social concerns. However, the treatment options for alcohol-use disorders have limited efficacy and exhibit a range of adverse drug reactions. Large numbers of preclinical studies have projected a biogenic amine, agmatine as a promising potential treatment option for drug addiction, including alcoholism. In the present study, administration of agmatine (20-40 mg/kg, i.p.) resulted in significant inhibition of ethanol self-administration in the right p-VTA in operant conditioning paradigm. Further, acute intracranial administration of agmatine (20 and 40 μg/rat) significantly reduced the ethanol consumption in the two bottle choice paradigm. Agmatine is degraded to putrescine and guanido-butanoic acid by the enzyme agmatinase and diamine oxidase respectively and inhibition of these enzymes results in augmentation of endogenous agmatine. In the present study, diamine oxidase inhibitor, aminoguanidine and agmatinase inhibitor, arcaine were used to block the agmatine metabolic pathways to increase brain agmatine levels. Drugs that augment endogenous agmatine levels like L-arginine (80 μg/rat, i.c.v.) or arcaine (50 μg/rat, i.c.v.) and aminoguanidine (25 μg/rat, i.c.v.) also reduced the ethanol consumption following their central administration. The pharmacological effect of agmatine on ethanol consumption was potentiated by imidazoline receptor agonists, I1 agonist moxonidine (25 μg/rat, i.c.v.), and imidazoline I2 agonist, 2-BFI (10 μg/rat, i.c.v.) and was blocked by imidazoline I1 antagonist, efaroxan (10 μg/rat, i.c.v.), and I2 antagonist, idazoxan (4 μg/rat, i.c.v.) at their ineffective doses per se. Thus, our result suggests the involvement of imidazoline I1 and I2 receptors in agmatine induced inhibition of ethanol consumption in rats.

Keywords:  Agmatine; Ethanol consumption; Imidazoline receptors; Operant conditioning; Two bottle choice paradigm

DOI:  https://doi.org/10.1016/j.pbb.2019.172779
Biochem Biophys Res Commun. 2019 Sep 04. pii: S0006-291X(19)31698-5. [Epub ahead of print]

Spermidine ameliorates liver ischaemia-reperfusion injury through the regulation of autophagy by the AMPK-mTOR-ULK1 signalling pathway.

Hao Liu, Jiayong Dong, Shaohua Song, Yuanyu Zhao, Jiyuan Wang, Zhiren Fu, Jinghui Yang.

   BACKGROUND: Hepatic ischaemia-reperfusion (IR) injury is a common clinical challenge lacking effective therapy. The aim of this study was to investigate whether spermidine has protective effects against hepatic IR injury through autophagy.
METHODS: Liver ischaemia reperfusion was induced in male C57BL/6 mice. Then, liver function, histopathology, cytokine production and immunofluorescence were evaluated to assess the impact of spermidine pre-treatment on IR-induced liver injury. Autophagosome formation was observed by transmission electron microscopy. Western blotting was used to explore the underlying mechanism and its relationship with autophagy, and TUNEL staining was conducted to determine the relationship between apoptosis and autophagy in the ischaemic liver.
RESULTS: The results of the transaminase assay, histopathological examination, and pro-inflammatory cytokine production and immunofluorescence evaluations demonstrated that mice pre-treated with spermidine showed significantly preserved liver function. Further experiments demonstrated that mice administered spermidine before the induction of IR exhibited increased autophagy via the AMPK-mTOR-ULK1 pathway, and TUNEL staining revealed that spermidine attenuated IR-induced apoptosis in the liver.
CONCLUSIONS: Our results provide the first line of evidence that spermidine provides protection against IR-induced injury in the liver by regulating autophagy through the AMPK-mTOR-ULK1 signalling pathway. These results suggest that spermidine may be beneficial for hepatic IR injury.

Keywords:  Autophagy; Ischaemia-reperfusion injury; Spermidine

DOI:  https://doi.org/10.1016/j.bbrc.2019.08.162
Nat Rev Cancer. 2019 Sep 12.

Methionine metabolism in health and cancer: a nexus of diet and precision medicine.

Sydney M Sanderson, Xia Gao, Ziwei Dai, Jason W Locasale.

Methionine uptake and metabolism is involved in a host of cellular functions including methylation reactions, redox maintenance, polyamine synthesis and coupling to folate metabolism, thus coordinating nucleotide and redox status. Each of these functions has been shown in many contexts to be relevant for cancer pathogenesis. Intriguingly, the levels of methionine obtained from the diet can have a large effect on cellular methionine metabolism. This establishes a link between nutrition and tumour cell metabolism that may allow for tumour-specific metabolic vulnerabilities that can be influenced by diet. Recently, a number of studies have begun to investigate the molecular and cellular mechanisms that underlie the interaction between nutrition, methionine metabolism and effects on health and cancer.

DOI: https://doi.org/10.1038/s41568-019-0187-8
Brain Res. 2019 Sep 10. pii: S0006-8993(19)30492-5. [Epub ahead of print] 146438

Antidepressant-like effects of agmatine and NOS inhibitors in chronic unpredictable mild stress model of depression in rats: The involvement of NLRP inflammasomes.

Ceren Sahin Ozkartal, Erdem Tuzun, Cem Ismail Kucukali, Canan Ulusoy, Murat Giris, Feyza Aricioglu.

  Innate immunity activation in the central nervous system (CNS) is known to contribute to the development of depression through NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasome assembly. Furthermore, administration of agmatine (AGM), a nitric oxide synthase (NOS) inhibitor, reverses stress-induced NLRP3 inflammasome activation in rats. We examined the effects of chronically-administered nitric oxide (NO) pathway modulating drugs on NLRP1/3-mediated neuroinflammatory responses and depressive-like behaviors in chronic unpredictable mild stress (CUMS) depression model of rats. CUMS model was applied to the adult male Sprague-Dawley rats for 6 weeks and the treatments were daily administered via intraperitoneal route in the last 3 weeks of CUMS procedure. Depressive-like behaviors were assessed by sucrose preference and forced swimming tests. The levels of NLRP inflammasome components (NLRP1, NLRP3, ASC, caspase-1 and IL-1β) were investigated in the prefrontal cortex by real time PCR and western blot methods. CUMS-induced depressive-like behaviors were coupled with the overactivation of NLRP1 and NLRP3 inflammasome sensors and increased levels of IL-1β. Depressive-like behaviors were ameliorated by chronic AGM and NOS inhibitor treatments. AGM and other NOS inhibitor treatments were found to be more effective in suppressing NLRP3 and NLRP1, respectively. All inhibitor reagents downregulated inflammasome components and IL-1β. These results suggest that both neuronal NLRP1 and microglial NLRP3 inflammasomes are involved in chronic stress-induced depressive-like behaviors. The antidepressant effects of AGM, iNOS and nNOS inhibitors are associated with the downregulation of CNS inflammasome expression levels. NO-pathway modulating drugs might provide novel therapeutic strategies for depression.

Keywords:  Depression; NLRP1; NLRP3; NOS inhibitors; agmantine; inflammasome

DOI:  https://doi.org/10.1016/j.brainres.2019.146438
J Cell Mol Med. 2019 Sep 09.

MCU Up-regulation contributes to myocardial ischemia-reperfusion Injury through calpain/OPA-1-mediated mitochondrial fusion/mitophagy Inhibition.

Lichun Guan, Zhimei Che, Xiangdong Meng, Yong Yu, Minghui Li, Ziqin Yu, Hui Shi, Dicheng Yang, Min Yu.

  Mitochondrial dynamic disorder is involved in myocardial ischemia/reperfusion (I/R) injury. To explore the effect of mitochondrial calcium uniporter (MCU) on mitochondrial dynamic imbalance under I/R and its related signal pathways, a mouse myocardial I/R model and hypoxia/reoxygenation model of mouse cardiomyocytes were established. The expression of MCU during I/R increased and related to myocardial injury, enhancement of mitochondrial fission, inhibition of mitochondrial fusion and mitophagy. Suppressing MCU functions by Ru360 during I/R could reduce myocardial infarction area and cardiomyocyte apoptosis, alleviate mitochondrial fission and restore mitochondrial fusion and mitophagy. However, spermine administration, which could enhance MCU function, deteriorated the above-mentioned myocardial cell injury and mitochondrial dynamic imbalanced. In addition, up-regulation of MCU promoted the expression and activation of calpain-1/2 and down-regulated the expression of Optic atrophy type 1 (OPA1). Meantime, in transgenic mice (overexpression calpastatin, the endogenous inhibitor of calpain) I/R model and OPA1 knock-down cultured cell. In I/R models of transgenic mice over-expressing calpastatin, which is the endogenous inhibitor of calpain, and in H/R models with siOPA1 transfection, inhibition of calpains could enhance mitochondrial fusion and mitophagy, and inhibit excessive mitochondrion fission and apoptosis through OPA1. Therefore, we conclude that during I/R, MCU up-regulation induces calpain activation, which down-regulates OPA1, consequently leading to mitochondrial dynamic imbalance.

Keywords:  calpain; ischemia/reperfusion (I/R); mitochondrial calcium uniporter (MCU); mitochondrial fission; mitophagy

DOI:  https://doi.org/10.1111/jcmm.14662