Ornithine Metabolism Research Articles

N2-Acetylornithine deacetylase functions as a Cys-Gly dipeptidase in the cytosolic glutathione degradation pathway in Arabidopsis thaliana.

Glutathione (GSH) is required for various physiological processes in plants, including redox regulation and detoxification of harmful compounds. GSH also functions as a repository for assimilated sulfur and is actively catabolized in plants. In Arabidopsis, GSH is mainly degraded initially by cytosolic enzymes, γ-glutamyl cyclotransferase, and γ-glutamyl peptidase, which release cysteinylglycine (Cys-Gly). However, the subsequent enzyme responsible for catabolizing this dipeptide has not been identified to date. In the present study, we identified At4g17830 as a Cys-Gly dipeptidase, namely cysteinylglycine peptidase 1 (CGP1). CGP1 complemented the phenotype of the yeast mutant that cannot degrade Cys-Gly. The Arabidopsis cgp1 mutant had lower Cys-Gly degradation activity than the wild type and showed perturbed concentrations of thiol compounds. Recombinant CGP1 showed reasonable Cys-Gly degradation activity in vitro. Metabolomic analysis revealed that cgp1 exhibited signs of severe sulfur deficiency, such as elevated accumulation of O-acetylserine (OAS) and the decrease in sulfur-containing metabolites. Morphological changes observed in cgp1, including longer primary roots of germinating seeds, were also likely associated with sulfur starvation. Notably, At4g17830 has previously been reported to encode an N2-acetylornithine deacetylase (NAOD) that functions in the ornithine biosynthesis. The cgp1 mutant did not show a decrease in ornithine content, whereas the analysis of CGP1 structure did not rule out the possibility that CGP1 has Cys-Gly dipeptidase and NAOD activities. Therefore, we propose that CGP1 is a Cys-Gly dipeptidase that functions in the cytosolic GSH degradation pathway and may play dual roles in GSH and ornithine metabolism.

Dysregulation of acyl carnitines, pentose phosphate pathway and arginine and ornithine metabolism are associated with decline in intrinsic capacity in Chinese older adults

BackgroundIntrinsic capacity is the combination of individual physical and mental abilities, reflecting the aging degree of the older adults. However, the mechanisms and metabolic characteristics of the decline in intrinsic capacity are still unclear.AimsTo identify metabolic signatures and associated pathways of decline in intrinsic capacity based on the metabolite features.MethodsWe recruited 70 participants aged 77.19 ± 8.31 years. The five domains of intrinsic capacity were assessed by Short Physical Performance Battery (for mobility), Montreal cognition assessment (for cognition), 30-Item Geriatric Depression Scale (for psychology), self-reported hearing/visual impairment (for sensory) and Nutritional risk screening (for vitality), respectively. The serum samples of participants were analyzed by liquid chromatography-mass spectrometry-based metabolomics, followed by metabolite set enrichment analysis and metabolic pathway analysis.ResultsThere were 50 participants with a decline in intrinsic capacity in at least one of the domains. A total of 349 metabolites were identified from their serum samples. Overall, 24 differential metabolites, 5 metabolite sets and 13 pathways were associated with the decline in intrinsic capacity.DiscussionOur results indicated that decline in intrinsic capacity had unique metabolomic profiles.ConclusionThe specific change of acyl carnitines was observed to be a feature of decline in intrinsic capacity. Dysregulation of the pentose phosphate pathway and of arginine and ornithine metabolism was strongly associated with the decline in intrinsic capacity.

Metabolic Assessment in Non-Dialysis Patients with Chronic Kidney Disease.

The aim of this study was to investigate the changes of different metabolites in the body fluids of non-dialysis patients with chronic kidney disease (CKD) using a metabolomics approach. The goal was to identify early biomarkers of CKD progression through metabolic pathway analysis. Plasma samples from 47 patients with stages 1-4 CKD not requiring dialysis and 30 healthy controls were analyzed by liquid chromatography-mass spectrometry (LC-MS). Using multivariate data analysis, specifically a partially orthogonal least squares discriminant analysis model (OPLS-DA), we investigated metabolic differences between different stages of CKD. The sensitivity and specificity of the analysis were evaluated using the Area Under Curve (AUC) method. Furthermore, the metabolic pathways were analyzed using the Met PA database. Plasma samples from CKD patients and controls were successfully differentiated using an OPLS-DA model. Initially, twenty-five compounds were identified as potential plasma metabolic markers for distinguishing CKD patients from healthy controls. Among these, six compounds (ADMA, D-Ornithine, Kynurenine, Kynurenic acid, 5-Hydroxyindoleacetic acid, and Gluconic acid) were found to be associated with CKD progression It has been found to be associated with the progression of CKD. Changes in metabolic pathways associated with CKD progression include arginine and ornithine metabolism, tryptophan metabolism, and the pentose phosphate pathway. By analyzing the metabolic pathways of different metabolites, we have identified the significant impact of CKD progression. The main metabolic pathways involved are Arginine and Ornithine metabolism, Tryptophan metabolism, and Pentose phosphate pathway. ADMA, D-Ornithine, L-Kynurenine, Kynurenic acid, 5-Hydroxyindoleacetic acid, and Gluconic acid could serve as potential early biomarkers for CKD progression. These findings have important implications for the early intervention and treatment of CKD, as well as for further research into the underlying mechanisms of its pathogenesis.

Multi-dimensional metabolomic profiling reveals dysregulated ornithine metabolism hallmarks associated with a severe acute pancreatitis phenotype

To reveal dysregulated metabolism hallmark that was associated with a severe acute pancreatitis (SAP) phenotype. In this study, LC-MS/MS-based targeted metabolomics was used to analyze plasma samples from 106 acute pancreatitis (AP) patients (34 mild, 38 moderate, and 34 severe) admitted within 48 hours from abdominal pain onset and 41 healthy controls. Temporal metabolic profiling was performed on days 1, 3, and 7 after admission. A random forest (RF) was performed to significantly determine metabolite differences between SAP and non-SAP (NSAP) groups. Mass spectrometry imaging (MSI) and immunohistochemistry were conducted for the examination of pancreatic metabolite and metabolic enzyme alterations, respectively, on necrosis and paracancerous tissues. Simultaneously determination of serum and pancreatic tissue metabolic alterations using an L-ornithine-induced AP model to discover metabolic commonalities. Twenty-two significant differential metabolites screened by RF were selected to build an accurate model for the prediction of SAP from NSAP (AUC = 0.955). Six of 22 markers were found by MSI with significant alterations in pancreatic lesions, reduced ornithine-related metabolites were also identified. The abnormally expressed arginase2 and ornithine transcarboxylase were further discovered in combination with time-course metabolic profiling in the SAP animal models, the decreased ornithine catabolites were found at a late stage of inflammation, but ornithine-associated metabolic enzymes were activated during the inflammatory process. The plasma metabolome of AP patients is distinctive, which shows promise for early SAP diagnosis. AP aggravation is linked to the activated ornithine metabolic pathway and its inadequate levels of catabolites in in-situ lesion.

Integrated volatile compounds and non-targeted metabolomics analysis reveal the characteristic flavor formation of proteins in grouper (Epinephelus coioides) during cold storage

Microorganisms, lipids, and proteins always interact in a complex way in the fish matrix, which becomes a hindrance to evaluate the quality of the individual factors affecting them. In order to investigate the relationship between protein deterioration and volatile compounds (VOCs) in grouper during cold storage, the myofibril protein (MP) was used as a single-factor study to exclude microorganisms and lipids effects. The oxidation and degradation of MP during storage at 4 ℃ were evaluated, including MP content, total sulfhydryl content, carbonyl content, spatial structure and microstructure. Headspace-solid phase microextraction- gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze the VOCs of grouper MP, and a total of 7 key VOCs were selected, including three ketones (2-nonanone, 2-undecanone and 2-tridecanone), three esters (methyl butyrate, methyl palmitate and methyl ester 9-octadecenoic acid) and one alcohol (3-methyl-1-butanol). At the same time, a non-targeted metabolomics method based on UPLC-Q-Extractive Orbitrap was used to investigate the changes in metabolites during MP storage. A total of 107 up-regulated differential metabolites and 7 down-regulated metabolites were annotated, and 6 metabolic pathways highly related to proteins were screened. Spearman correlation analysis showed that 7 key VOCs are associated with the biosynthesis and metabolism of ornithine and lysine. And a possible solution to protein deterioration in grouper was proposed, which provided a reference for improving protein quality and regulating flavor formation during cold storage of grouper at source.

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.

Ornithine metabolism and the osmotic stress response in mytilid congeners

ABSTRACT Previous transcriptomic studies have suggested that ornithine decarboxylase (ODC) expression in Mytilids (Mytilus spp.) may be a critical component of the osmotic stress response. Ornithine is catabolized into polyamines by ODC or into glutamate or proline by ornithine aminotransferase (OAT). To better understand how ornithine is metabolized under low salinity conditions, we examined species-specific variation in OAT and ODC expression for three species that vary in their salinity tolerance (M. trossulus, M. edulis, and M. galloprovincialis). We found a consistent decrease in ODC expression during hypoosmotic exposure in all three species but pronounced species-specific increases in OAT expression. During hyperosmotic stress, the patterns of expression of these genes reversed, suggesting that proline or glutamate synthesis is important during low salinity exposure, while polyamine synthesis may be more important during hyperosmotic exposure. These responses were most pronounced in M. galloprovincialis, with an 18-fold increase in OAT during hypoosmotic exposure.

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 30min 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.

A Study of the Metabolic Pathways Affected by Gestational Diabetes Mellitus: Comparison with Type 2 Diabetes.

Gestational diabetes mellitus (GDM) remains incompletely understood and increases the risk of developing Diabetes mellitus type 2 (DM2). Metabolomics provides insights etiology and pathogenesis of disease and discovery biomarkers for accurate detection. Nuclear magnetic resonance (NMR) spectroscopy is a key platform defining metabolic signatures in intact serum/plasma. In the present study, we used NMR-based analysis of macromolecules free-serum to accurately characterize the altered metabolic pathways of GDM and assessing their similarities to DM2. Our findings could contribute to the understanding of the pathophysiology of GDM and help in the identification of metabolomic markers of the disease. Sixty-two women with GDM matched with seventy-seven women without GDM (control group). 1H NMR serum spectra were acquired on an 11.7 T Bruker Avance DRX NMR spectrometer. We identified 55 metabolites in both groups, 25 of which were significantly altered in the GDM group. GDM group showed elevated levels of ketone bodies, 2-hydroxybutyrate and of some metabolic intermediates of branched-chain amino acids (BCAAs) and significantly lower levels of metabolites of one-carbon metabolism, energy production, purine metabolism, certain amino acids, 3-methyl-2-oxovalerate, ornithine, 2-aminobutyrate, taurine and trimethylamine N-oxide. Metabolic pathways affected in GDM were beta-oxidation, ketone bodies metabolism, one-carbon metabolism, arginine and ornithine metabolism likewise in DM2, whereas BCAAs catabolism and aromatic amino acids metabolism were affected, but otherwise than in DM2.

Metabolomic alterations in the blood plasma of older adults with mild cognitive impairment and Alzheimer’s disease (from the Nakayama Study)

Alzheimer's disease (AD) is a progressive disease, and the number of AD patients is increasing every year as the population ages. One of the pathophysiological mechanisms of AD is thought to be the effect of metabolomic abnormalities. There have been several studies of metabolomic abnormalities of AD, and new biomarkers are being investigated. Metabolomic studies have been attracting attention, and the aim of this study was to identify metabolomic biomarkers associated with AD and mild cognitive impairment (MCI). Of the 927 participants in the Nakayama Study conducted in Iyo City, Ehime Prefecture, 106 were selected for this study as Control (n = 40), MCI (n = 26), and AD (n = 40) groups, matched by age and sex. Metabolomic comparisons were made across the three groups. Then, correlations between metabolites and clinical symptoms were examined. The blood mRNA levels of the ornithine metabolic enzymes were also measured. Of the plasma metabolites, significant differences were found in ornithine, uracil, and lysine. Ornithine was significantly decreased in the AD group compared to the Control and MCI groups (Control vs. AD: 97.2 vs. 77.4; P = 0.01, MCI vs. AD: 92.5 vs. 77.4; P = 0.02). Uracil and lysine were also significantly decreased in the AD group compared to the Control group (uracil, Control vs. AD: 272 vs. 235; P = 0.04, lysine, Control vs. AD: 208 vs. 176; P = 0.03). In the total sample, the MMSE score was significantly correlated with lysine, ornithine, thymine, and uracil. The Barthel index score was significantly correlated with lysine. The instrumental activities of daily living (IADL) score were significantly correlated with lysine, betaine, creatine, and thymine. In the ornithine metabolism pathway, the spermine synthase mRNA level was significantly decreased in AD. Ornithine was decreased, and mRNA expressions related to its metabolism were changed in the AD group compared to the Control and MCI groups, suggesting an association between abnormal ornithine metabolism and AD. Increased betaine and decreased methionine may also have the potential to serve as markers of higher IADL in elderly persons. Plasma metabolites may be useful for predicting the progression of AD.

Compromised glycolysis contributes to foot process fusion of podocytes in diabetic kidney disease: Role of ornithine catabolism

IntroductionCompromised glycolysis in podocytes contributes to the initiation of diabetic kidney disease (DKD). Podocyte injury is characterized by cytoskeletal remodeling and foot process fusion. Compromised glycolysis in diabetes likely leads to switch of energy supply in podocyte. However, the underlying mechanism by which disturbed energy supply in podocytes affects the cytoskeletal structure of podocytes remains unclear. MethodsMetabolomic and transcriptomic analyses were performed on the glomeruli of db/db mice to examine the catabolism of glucose, fatty, and amino acids. Ornithine catabolism was targeted in db/db and podocyte-specific pyruvate kinase M2 knockout (PKM2-podoKO) mice. In vitro, expression of ornithine decarboxylase (ODC1) was modulated to investigate the effect of ornithine catabolism on mammalian target of rapamycin (mTOR) signaling and cytoskeletal remodeling in cultured podocytes. ResultsMulti-omic analyses of the glomeruli revealed that ornithine metabolism was enhanced in db/db mice compared with that in db/m mice under compromised glycolytic conditions. Additionally, ornithine catabolism was exaggerated in podocytes of diabetic PKM2-podoKO mice compared with that in diabetic PKM2flox/flox mice. In vivo, difluoromethylornithine (DFMO, inhibitor of ODC1) administration reduced urinary albumin excretion and alleviated podocyte foot process fusion in db/db mice. In vitro, 2-deoxy-d-glucose (2-DG) exposure induced mTOR signaling activation and cytoskeletal remodeling in podocytes, which was alleviated by ODC1-knockdown. Mechanistically, a small GTPase Ras homolog enriched in the brain (Rheb), a sensor of mTOR signaling, was activated by exposure to putrescine, a metabolic product of ornithine catabolism. ConclusionThese findings demonstrate that compromised glycolysis in podocytes under diabetic conditions enhances ornithine catabolism. The metabolites of ornithine catabolism contribute to mTOR signaling activation via Rheb and cytoskeletal remodeling in podocytes in DKD.

Metformin Induces PRODH/POX-Dependent Apoptosis in Breast Cancer Cells.

Although the antineoplastic activity of metformin (MET) is well established, the underlying mechanism of the activity is not understood. Since MET activates AMP kinase (AMPK) and proline dehydrogenase/proline oxidase (PRODH/POX) is stimulated by AMPK ligands (implicated in the regulation of cancer cell survival/apoptosis), the effect of MET on PRODH/POX-dependent apoptosis in wild-type MCF-7 cells (MCF-7WT) and POX knockdown MCF-7 cells (MCF-7crPOX cells) was studied. PRODH/POX catalyzes proline degradation generating ROS-induced apoptosis or autophagy. Availability of proline for PRODH/POX functions is regulated by the activity of prolidase (enzyme releasing proline from imidodipeptides), collagen biosynthesis (process consuming proline), and metabolism of proline, ornithine, and glutamic acid. We have found that MET is cytotoxic for MCF-7 cells (IC50∼17 mM), and to the lower extent for MCF-7crPOX cells (IC50∼28 mM). In MCF-7WT cells, the effect was accompanied by the inhibition of DNA biosynthesis, collagen biosynthesis, stimulation of ROS formation, AMPKα phosphorylation, and expression of prolidase, p53, caspase 8, caspase 9, and cleaved PARP. In MET-treated MCF-7crPOX cells, the processes were less affected than in MCF-7WT cells and the expression of caspase 9 was decreased, while cleaved caspase 8 and cleaved PARP were not detected. The effects were accompanied by an increase in the prolidase activity and proline concentration. The mechanism for MET-induced apoptosis involves the up-regulation of prolidase activity and a decrease in collagen biosynthesis contributing to an increase in the concentration of substrate (proline) for PRODH/POX-dependent ROS formation and activation of caspases −9 and −8. The data suggest that PRODH/POX participates in the MET-induced intrinsic and extrinsic apoptosis in MCF-7 cells.

Human Decidual Mesenchymal Stem Cells Obtained From Early Pregnancy Improve Cardiac Revascularization Postinfarction by Activating Ornithine Metabolism.

BackgroundCompared with bone marrow mesenchymal stem cells (BMSCs), decidual mesenchymal stem cells (DMSCs) are easy to obtain and exhibit excellent angiogenic effects, but their role in cell transplantation after myocardial infarction (MI) remains unclear.MethodsBMSCs and DMSCs were harvested from healthy donors. The effects of both cell types on angiogenesis were observed in vitro. Metabonomics analysis was performed to compare different metabolites and screen critical metabolic pathways. A murine model of acute myocardial infarction (AMI) was established, which was randomized into five groups (control, BMSC, DMSC, DMSC + ODCshRNA and BMSC + ODC consisting of 50 animals, equally divided into each group). The therapeutic effect of DMSCs on MI in rats was assessed based on neovascularization and cardiac remodeling.ResultsDMSCs exhibited a better angiogenic effect on human umbilical vein endothelial cells (HUVECs) than BMSCs in vitro. In addition, ornithine metabolism, which is associated with vascularization, was significantly increased in DMSCs. The transplantation of DMSCs in the rat MI model significantly enhanced angiogenesis of the infarct border area and improved cardiac remodeling and dysfunction postinfarction compared with BMSCs. Furthermore, inhibition of ornithine metabolism by silencing ornithine decarboxylase (ODC) in DMSCs partly abolished the benefits of DMSC transplantation.ConclusionCompared with BMSCs, DMSCs exhibited better efficacy in improving revascularization and heart remodeling post-MI via the activation of ODC-associated ornithine metabolism.

Photosynthesis-related physiology and metabolomics responses of Polygonum lapathifolium in contrasting manganese environments.

Manganese (Mn) plays an essential role in plant growth; however, excessive Mn is toxic to plants. Polygonum lapathifolium Linn. was tested as a novel Mn-hyperaccumulating species in our previous study, but the underlying mechanisms of this hyperaccumulation are poorly understood. A hydroponic experiment with (8mmolL-1 ) and without additional Mn (CK) was established to explore the possible mechanisms through the effects on photosynthesis-related physiological characteristics and metabolomics. The results showed that additional Mn increased plant biomass, photosynthesis, and stomatal conductance related to increases in the effective photochemical quantum yield of photosystem II and relative electron transport rate (P <0.05). The results from liquid chromatography-mass spectrometry revealed 56 metabolites differentially accumulated between the plants composing these two groups. Metabolites were enriched in 20 metabolic pathways at three levels (environmental information processing, genetic information processing, and metabolism), of which five metabolic pathways were associated with significant or extremely significant changes (P <0.05). These five enriched pathways were ABC transporters (environmental information processing), aminoacyl-tRNA biosynthesis (genetic information processing), biosynthesis of amino acids , d -arginine and d -ornithine metabolism , and arginine biosynthesis (metabolism). Flavonoids may play a key role in Mn tolerance, as they accumulated more than 490-fold, and the relationship between flavonoids and Mn tolerance needs to be studied in the future.

Effect of polysaccharides from Tibetan turnip (Brassica rapa L.) on the gut microbiome after in vitro fermentation and in vivo metabolism.

Tibetan turnip (Brassica rapa L.) polysaccharide (TTP) is an active ingredient and has been studied for many years due to its biological effect. There are a few studies on its digestion properties and the regulation of the intestinal microbiota. In this study, the regulation of intestinal health by TTP was investigated in vitro and in vivo. The results showed that TTP was not degraded after simulated gastrointestinal digestion. When TTP was fermented by the gut microbiota, the content of short-chain fatty acids (SCFAs) and the relative abundance of Bifidobacterium, Catenibacterium increased; the relative abundance of Prevotella, Phascolarctobacterium decreased. The in vivo experiments showed that TTP could reduce the abundances of Muribaculaceae and enrich Lactobacillus. The results of KEGG indicated that TTP could promote arginine and ornithine metabolism, fructose and mannose metabolism, and lipopolysaccharide biosynthesis. These data showed that TTP exerted its prebiotic effect by regulating the intestinal flora and could be used for preventing disease and improving health by maintaining intestinal health.

Understanding the Role of Estrogen Receptor Status in PRODH/POX-Dependent Apoptosis/Survival in Breast Cancer Cells.

Simple SummaryThe estrogen receptor (ER) status and the availability of agonists or antagonists of these receptors determine the processes of growth, differentiation, and proliferation of breast cancer cells. Estrogens and anti-estrogenic compounds have been shown to influence breast cancer cell survival/apoptosis via action through the mitochondrial enzyme proline dehydrogenase/proline oxidase (PRODH/POX). In this review, we highlight the molecular effects of ER stimulation/inhibition in signaling pathways.It has been suggested that activation of estrogen receptor α (ER α) stimulates cell proliferation. In contrast, estrogen receptor β (ER β) has anti-proliferative and pro-apoptotic activity. Although the role of estrogens in estrogen receptor-positive breast cancer progression has been well established, the mechanism of their effect on apoptosis is not fully understood. It has been considered that ER status of breast cancer cells and estrogen availability might determine proline dehydrogenase/proline oxidase (PRODH/POX)-dependent apoptosis. PRODH/POX is a mitochondrial enzyme that converts proline into pyrroline-5-carboxylate (P5C). During this process, ATP (adenosine triphosphate) or ROS (reactive oxygen species) are produced, facilitating cell survival or death, respectively. However, the critical factor in driving PRODH/POX-dependent functions is proline availability. The amount of this amino acid is regulated at the level of prolidase (proline releasing enzyme), collagen biosynthesis (proline utilizing process), and glutamine, glutamate, α-ketoglutarate, and ornithine metabolism. Estrogens were found to upregulate prolidase activity and collagen biosynthesis. It seems that in estrogen receptor-positive breast cancer cells, prolidase supports proline for collagen biosynthesis, limiting its availability for PRODH/POX-dependent apoptosis. Moreover, lack of free proline (known to upregulate the transcriptional activity of hypoxia-inducible factor 1, HIF-1) contributes to downregulation of HIF-1-dependent pro-survival activity. The complex regulatory mechanism also involves PRODH/POX expression and activity. It is induced transcriptionally by p53 and post-transcriptionally by AMPK (AMP-activated protein kinase), which is regulated by ERs. The review also discusses the role of interconversion of proline/glutamate/ornithine in supporting proline to PRODH/POX-dependent functions. The data suggest that PRODH/POX-induced apoptosis is dependent on ER status in breast cancer cells.

Oral Microbiota Identifies Patients in Early Onset Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is the most common autoimmune inflammatory disease, and single periodontitis-associated bacteria have been suggested in disease manifestation. Here, the oral microbiota was characterized in relation to the early onset of RA (eRA) taking periodontal status into consideration. 16S rRNA gene amplicon sequencing of saliva bacterial DNA from 61 eRA patients without disease-modifying anti-rheumatic drugs and 59 matched controls was performed. Taxonomic classification at 98.5% was conducted against the Human Oral Microbiome Database, microbiota functions were predicted using PICRUSt, and periodontal status linked from the Swedish quality register for clinically assessed caries and periodontitis. The participants were classified into three distinct microbiota-based cluster groups with cluster allocation differences by eRA status. Independently of periodontal status, eRA patients had enriched levels of Prevotella pleuritidis, Treponema denticola, Porphyromonas endodontalis and Filifactor alocis species and in the Porphyromonas and Fusobacterium genera and functions linked to ornithine metabolism, glucosylceramidase, beta-lactamase resistance, biphenyl degradation, fatty acid metabolism and 17-beta-estradiol-17-dehydrogenase metabolism. The results support a deviating oral microbiota composition already in eRA patients compared with healthy controls and highlight a panel of oral bacteria that may be useful in eRA risk assessment in both periodontally healthy and diseased persons.

A sleep-like state in Hydra unravels conserved sleep mechanisms during the evolutionary development of the central nervous system.

Sleep behaviors are observed even in nematodes and arthropods, yet little is known about how sleep-regulatory mechanisms have emerged during evolution. Here, we report a sleep-like state in the cnidarian Hydra vulgaris with a primitive nervous organization. Hydra sleep was shaped by homeostasis and necessary for cell proliferation, but it lacked free-running circadian rhythms. Instead, we detected 4-hour rhythms that might be generated by ultradian oscillators underlying Hydra sleep. Microarray analysis in sleep-deprived Hydra revealed sleep-dependent expression of 212 genes, including cGMP-dependent protein kinase 1 (PRKG1) and ornithine aminotransferase. Sleep-promoting effects of melatonin, GABA, and PRKG1 were conserved in Hydra However, arousing dopamine unexpectedly induced Hydra sleep. Opposing effects of ornithine metabolism on sleep were also evident between Hydra and Drosophila, suggesting the evolutionary switch of their sleep-regulatory functions. Thus, sleep-relevant physiology and sleep-regulatory components may have already been acquired at molecular levels in a brain-less metazoan phylum and reprogrammed accordingly.

Enzymes Involved in the Biosynthesis of Arginine from Ornithine in Maritime Pine (Pinus pinaster Ait.).

The amino acids arginine and ornithine are the precursors of a wide range of nitrogenous compounds in all living organisms. The metabolic conversion of ornithine into arginine is catalyzed by the sequential activities of the enzymes ornithine transcarbamylase (OTC), argininosuccinate synthetase (ASSY) and argininosuccinate lyase (ASL). Because of their roles in the urea cycle, these enzymes have been purified and extensively studied in a variety of animal models. However, the available information about their molecular characteristics, kinetic and regulatory properties is relatively limited in plants. In conifers, arginine plays a crucial role as a main constituent of N-rich storage proteins in seeds and serves as the main source of nitrogen for the germinating embryo. In this work, recombinant PpOTC, PpASSY and PpASL enzymes from maritime pine (Pinus pinaster Ait.) were produced in Escherichia coli to enable study of their molecular and kinetics properties. The results reported here provide a molecular basis for the regulation of arginine and ornithine metabolism at the enzymatic level, suggesting that the reaction catalyzed by OTC is a regulatory target in the homeostasis of ornithine pools that can be either used for the biosynthesis of arginine in plastids or other nitrogenous compounds in the cytosol.

Identification of potential urine biomarkers in idiopathic parkinson's disease using NMR

IntroductionParkinson’s disease (PD) is the most common neurodegenerative disease caused by the loss of dopamine chemicals resulting in urinary incontinence, gastrointestinal dysfunction, gait impairment and mitochondrial dysfunction. Study investigated urinary metabolic profiles of patients with idiopathic PD as compared to healthy controls (HC) to identify the potential biomarkers. MethodsUrine samples were collected from 100 PD subjects and 50 HC using standard protocol. Metabolomic analyses were performed using high resolution nuclear magnetic resonance (NMR) spectroscopy. The integral values of 17 significant metabolites were estimated and concentration values were calculated, which were subjected to univariate and multivariate statistical analysis. ResultsWe found significantly increased levels of ornithine, phenylalanine, isoleucine, β-hydroxybutyrate, tyrosine and succinate in the urine of patients with PD in comparison with HC. These metabolites exhibited area under the curve greater than 0.60 on ROC curve analysis. We also observed a significant association between succinate concentration and UPDRS motor scores of PD. DiscussionMetabolic pathway alterations were observed in aromatic amino acid metabolism, ketone bodies synthesis, branched chain amino acid metabolism and ornithine metabolism. Comprehensive metabolomic profiling revealed variations in urinary signatures associated with severity of idiopathic PD. This profiling relies on non-invasive sampling and is complementary to existing clinical modalities.