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Michael Aviram - One of the best experts on this subject based on the ideXlab platform.

  • Research Article Paraoxonase Activity and Expression Is Modulated by Therapeutics in Experimental Rat Nonalcoholic Fatty Liver Disease
    2013
    Co-Authors: M. Grozovski, Rachel Karry, I. Bersudsky, Michael Aviram
    Abstract:

    Copyright © 2012 O. Hussein et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective. The objective of the present study is to investigate the effect of rosiglitazone, metformin, ezetimibe, and valsartan (alone or in combinations) on paraoxonase (PON) activity and PON-mRNA expression in nonalcoholic fatty liver disease (NAFLD). Methods. 54 Male Sprague–Dawley rats were divided to 9 groups: chow diet group (15 weeks); methionine-choline-deficient diet (MCDD) group (15 weeks); MCDD-treated groups for the last 6 weeks with either metformin (M), rosiglitazone (R), metformin plus rosiglitazone (M+R), ezetimibe (E), valsartan (V), or a combination of R+M+V or of R+M+V+E for a total period of 15 weeks. Results. PON activities in serum and liver were decreased in MCDD rats. PON activity in serum increased significantly in all treatment groups. PON activity in liver was also increased significantly, except only in groups R, E, V, R+M+V, and R+M+V+E. Liver PON3 mRNA expression increased significantly in groups R+M, E, V, R+M+V, and R+M+V+E whereas liver PON2 mRNA expression increased significantly in MCDD, R+M, E, V, R+M+V, and R+M+V+E. Conclusions. PON activities in serum an

  • Paraoxonase Activity and Expression Is Modulated by Therapeutics in Experimental Rat Nonalcoholic Fatty Liver Disease
    Hindawi Limited, 2012
    Co-Authors: O. Hussein, Rachel Karry, Jamal Zidan, Imad Shams, S. Szvalb, M. Grozovski, I. Bersudsky, Abu K. Jabal, Michael Aviram
    Abstract:

    Objective. The objective of the present study is to investigate the effect of rosiglitazone, metformin, ezetimibe, and valsartan (alone or in combinations) on paraoxonase (PON) activity and PON-mRNA expression in nonalcoholic fatty liver disease (NAFLD). Methods. 54 Male Sprague–Dawley rats were divided to 9 groups: chow diet group (15 weeks); methionine-choline-deficient diet (MCDD) group (15 weeks); MCDD-treated groups for the last 6 weeks with either metformin (M), rosiglitazone (R), metformin plus rosiglitazone (M+R), ezetimibe (E), valsartan (V), or a combination of R+M+V or of R+M+V+E for a total period of 15 weeks. Results. PON activities in serum and liver were decreased in MCDD rats. PON activity in serum increased significantly in all treatment groups. PON activity in liver was also increased significantly, except only in groups R, E, V, R+M+V, and R+M+V+E. Liver PON3 mRNA expression increased significantly in groups R+M, E, V, R+M+V, and R+M+V+E whereas liver PON2 mRNA expression increased significantly in MCDD, R+M, E, V, R+M+V, and R+M+V+E. Conclusions. PON activities in serum and liver were decreased in NAFLD. Treatment with insulin sensitizers, ezetimibe, and valsartan increased PON activity and reduced oxidative stress both in serum and liver

  • the antioxidant hdl associated paraoxonase 1 pon1 attenuates diabetes development and stimulates β cell insulin release
    Atherosclerosis, 2011
    Co-Authors: Marie Korengluzer, Michael Aviram, Edna Meilin, Tony Hayek
    Abstract:

    Abstract Objective To analyze the direct effects of paraoxonase-1 (PON1) on diabetes development and on β-cell insulin release. Methods and results Injection of rePON1 to mice, prior to STZ-induced diabetes, resulted in reduced incidence of diabetes, as well as, in higher serum insulin levels. Incubation of β-cells with PON1 also dose-dependently increased insulin secretion and its cellular content. PON1 increased cell survival under high glucose levels, but not under high STZ concentrations. The addition of the PON1 carrier in the circulation – HDL, to βTC3 cell line, had an additive effect on PON1-induced insulin secretion. PON1 administration to mice or incubation with β-cells was associated with a substantial decreased oxidative stress. Just like PON1, the dietary anti-oxidants, pomegranate juice, punicalagin (major polyphenol in pomegranate) or vitamin E, also increased insulin release from βTC3, but unlike PON1, failed to increase insulin cellular content, suggesting a possible role for PON1 in insulin biosynthesis, separately from PON1 antioxidative effect. Both, PON1 catalytic activity and PON1 association to HDL, were not required for PON1 stimulation of insulin release from β-cells. However, the PON1 free sulfhydryl group was shown to be essential for insulin release by PON1, as blocking the PON1 SH group, abolished PON1 stimulatory effect on insulin secretion. Conclusion PON1 is a potent anti-diabetic enzyme that exerts this protection against diabetes through its antioxidative, as well as via its insulin stimulation properties on β-cells.

  • Characterization of the PON1 active site using modeling simulation, in relation to PON1 lactonase activity.
    Bioorganic & medicinal chemistry, 2008
    Co-Authors: Hagai Tavori, Michael Aviram, Soliman Khatib, Jacob Vaya
    Abstract:

    Abstract Paraoxonase1 (PON1) is a HDL bound enzyme and many of the anti-atherogenic properties of HDL are attributed to PON1. The enzyme precise mechanism of protective action and its endogenous substrate remain elusive. PON1 hydrolyzes organophosphates, arylesters and lactones, whereas the lactones activity is assumed as the physio/pathological one. This study is aimed to predict the location of the PON1 active site within PON1 crystal structure, and the lactone structure suitability as PON1 ligand, by employing modeling techniques. Based on such calculations the ligands–PON1 interactions were characterized, and relating lactones rate of hydrolysis revealed an inverse correlation with the docking energy of the ligands–PON1 complex, and a direct correlation with the lactone side chain length. In conclusion, this study characterized the PON1 possible active site and proposes a tool which may make it possible to envisage the structure of potential endogenous and exogenous lactones such as the PON1 ligand.

  • paraoxonases pon1 pon2 PON3 analyses in vitro and in vivo in relation to cardiovascular diseases
    Methods of Molecular Biology, 2008
    Co-Authors: Michael Aviram, Mira Rosenblat
    Abstract:

    Mammalian paraoxonases (PON1, PON2, PON3) are a unique family of calcium-dependent hydrolases, with enzymatic activities toward a broad range of substrates (lactones, thiolactones, carbonates, esters, phosphotriesters). Although PONs physiological substrates were not yet identified, some studies suggest that they could be some lactones, or some specific oxidized phospholipids, or products of both enzymatic and nonenzymatic oxidation of arachidonic and docosahexaenoic acid, as well as N-acyl-homoserine lactones (which are quorum-sensing signals of pathogenic bacteria). Since no endogenous substrates for PONs activity determination are available yet, synthetic substrates such as paraoxon, phenyl acetate, and several lactones are used for PONs activity assays. All three members of the PON family (PON 1/2/3) were shown to protect from atherosclerosis development. Their anti-atherogenic biological activities were studied in vitro using serum or cell cultures, and also in vivo, using PON 1/2/3 knockout or transgenic mice, as well as humans - healthy volunteers and atherosclerotic patients (diabetics, hypercholesterolemics, and hypertensives).

Srinivasa T Reddy - One of the best experts on this subject based on the ideXlab platform.

  • abstract 1472 paraoxonase 3 is a novel tumor suppressor protein in xenograft mouse model
    Cancer Research, 2020
    Co-Authors: Asokan Devarajan, Dawoud Sulaiman, Dorothy Nguyen, Robin Fariaseisner, Srinivasa T Reddy
    Abstract:

    Introduction: Dysfunction of mitochondrial respiratory chains or its associated machinery favors the aerobic glycolysis leading to upregulation of genes related to cell proliferation, metastasis, drug resistant and cancer cell stemness, i.e., the Warburg effect, which has a major role in the pathogenesis of tumor formation. Various studies have documented that perturbation of mitochondria leads to apoptosis suggesting that the precise spatiotemporal regulation of mitochondrial function is a critical regulator of both cell survival and death, whcih determine tumorigenesis. Paraoxonase 3 (PON3) is an intracellular protein localized to the mitochondrial associated membrane. PON3 binds coenzymes Q10 and regulates the respiratory complex activity and prevents the ubisemiquinone-mediated mitochondrial superoxide levels in response to stress conditions. PON3 deficiency leads to dysfunction of mitochondria, which along with an increase in mitochondrial oxidative stress causes systemic inflammation, atherosclerosis, obesity and gall stone formation. PON3 is upregulated in ovarian cancer tissues. However, it9s expression in various stages of ovarian cancer and its role on cancer development have not been studied. Hypothesis: PON3 expression may regulate the ovarian cancer development by enhancing the mitochondrial function. Methods and Results: Using human ovarian carcinoma tissue array, we identified that PON3 expression was higher in both early and late stages of ovarian cancer when compared to normal tissue. Interestingly, we demonstrated that overexpression of PON3 prevented tumor formation in a mouse ovarian cancer xenograft model. Overexpression of PON3, (i) reduced the tumor angiogenesis marker, CD31 levels in the tumor microenvironment and (ii) inhibited ovarian cancer cell proliferation in both normoxic and hypoxic condition in vitro. Moreover, PON3 reduced VEGF levels (but not IGF-1 levels) under hypoxic conditions. Furthermore, mechanistically, overexpression of PON3 decreased the VEGF level by accelerating the proteasome-dependent protein degradation of hypoxia inducible factor-1 α (HIF-1α) under hypoxic conditions. Finally, we demonstrate that the inhibitory effect of PON3 on HIF-1α levels is, in part, mediated by mitochondrial function. Conclusion: We report for the first time that PON3 functions as a tumor suppressor in ovarian cancer possibly by suppressing VEGF signaling via HIF-1α by enhancing the mitochondrial function suggesting that PON3 might be a successful strategy to inhibit the ovarian cancer development. Citation Format: Asokan Devarajan, Feng Su, Dawoud Sulaiman, Dorothy Nguyen, Robin Farias-Eisner, Srinivasa T. Reddy. Paraoxonase 3 is a novel tumor suppressor protein in xenograft mouse model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1472.

  • pon2 deficiency leads to increased susceptibility to diet induced obesity
    Antioxidants, 2019
    Co-Authors: Diana M Shih, Alan M. Fogelman, Aldons J Lusis, Yonghong Meng, Tamer Sallam, Laurent Vergnes, Michelle L Shu, Karen Reue, Peter Tontonoz, Srinivasa T Reddy
    Abstract:

    (1) Background: Paraoxonase 2 (PON2) is a ubiquitously expressed protein localized to endoplasmic reticulum and mitochondria. Previous studies have shown that PON2 exhibits anti-oxidant and anti-inflammatory functions, and PON2-deficient (PON2-def) mice are more susceptible to atherosclerosis. Furthermore, PON2 deficiency leads to impaired mitochondrial function. (2) Methods: In this study, we examined the susceptibility of PON2-def mice to diet-induced obesity. (3) Results: After feeding of an obesifying diet, the PON2-def mice exhibited significantly increased body weight due to increased fat mass weight as compared to the wild-type (WT) mice. The increased adiposity was due, in part, to increased adipocyte hypertrophy. PON2-def mice had increased fasting insulin levels and impaired glucose tolerance after diet-induced obesity. PON2-def mice had decreased oxygen consumption and energy expenditure. Furthermore, the oxygen consumption rate of subcutaneous fat pads from PON2-def mice was lower compared to WT mice. Gene expression analysis of the subcutaneous fat pads revealed decreased expression levels of markers for beige adipocytes in PON2-def mice. (4) Conclusions: We concluded that altered systemic energy balance, perhaps due to decreased beige adipocytes and mitochondrial dysfunction in white adipose tissue of PON2-def mice, leads to increased obesity in these mice.

  • macrophage paraoxonase 2 regulates calcium homeostasis and cell survival under endoplasmic reticulum stress conditions and is sufficient to prevent the development of aggravated atherosclerosis in paraoxonase 2 deficiency apoe mice on a western diet
    Molecular Genetics and Metabolism, 2012
    Co-Authors: Asokan Devarajan, Noam Bourquard, Victor Grijalva, David Meriwether, Satoshi Imaizumi, Bochul Shin, Sherin U Devaskar, Srinivasa T Reddy
    Abstract:

    Abstract Paraoxonase 2 deficiency (PON2-def) alters mitochondrial function and exacerbates the development of atherosclerosis in mice. PON2 overexpression protects against ER stress in cell culture. In this paper, we examined the role of PON2 in the unexplored link between ER stress and mitochondrial dysfunction and tested whether restoration of PON2 in macrophages is sufficient to reduce aggravated atherosclerosis in PON2-def/apoE −/− mice on a Western diet. ER stress response genes, intracellular calcium levels, and apoptotic nuclei were significantly elevated in PON2-def/apoE −/− macrophages compared to apoE −/− macrophages in response to ER stressors, but not at the basal level. In contrast, PON2-def/apoE −/− macrophages exhibited greater mitochondrial stress at the basal level, which was further worsened in response to ER stressors. There was no difference in ER stress response genes and apoptotic nuclei between apoE −/− and PON2-def/apoE −/− macrophages when pretreated with xestospongin (which blocks the release of calcium from ER) suggesting that PON2 modulates cell survival and ER stress by maintaining calcium homeostasis. Treatment with a mitochondrial calcium uptake inhibitor, RU360, attenuated ER stressor mediated mitochondrial dysfunction in PON2-def/apoE −/− macrophages. CHOP expression (ER stress marker) and apoptotic nuclei were significantly higher in aortic lesions of PON2-def/apoE −/− mice compared to apoE −/− mice fed a Western diet. Restoration of PON2 in macrophages reduced ER stress, mitochondrial dysfunction and apoptosis in response to ER stressors. Furthermore, restoration of PON2 in macrophages reduced lesional apoptosis and atherosclerosis in PON2-def/apoE −/− mice on a Western diet. Our data suggest that macrophage PON2 modulates mechanisms that link ER stress, mitochondrial dysfunction and the development of atherosclerosis.

  • protectors or traitors the roles of pon2 and PON3 in atherosclerosis and cancer
    Journal of Lipids, 2012
    Co-Authors: Ines Witte, Srinivasa T Reddy, Ulrich Foerstermann, Asokan Devarajan, Sven Horke
    Abstract:

    Cancer and atherosclerosis are major causes of death in western societies. Deregulated cell death is common to both diseases, with significant contribution of inflammatory processes and oxidative stress. These two form a vicious cycle and regulate cell death pathways in either direction. This raises interest in antioxidative systems. The human enzymes paraoxonase-2 (PON2) and PON3 are intracellular enzymes with established antioxidative effects and protective functions against atherosclerosis. Underlying molecular mechanisms, however, remained elusive until recently. Novel findings revealed that both enzymes locate to mitochondrial membranes where they interact with coenzyme Q10 and diminish oxidative stress. As a result, ROS-triggered mitochondrial apoptosis and cell death are reduced. From a cardiovascular standpoint, this is beneficial given that enhanced loss of vascular cells and macrophage death forms the basis for atherosclerotic plaque development. However, the same function has now been shown to raise chemotherapeutic resistance in several cancer cells. Intriguingly, PON2 as well as PON3 are frequently found upregulated in tumor samples. Here we review studies reporting PON2/PON3 deregulations in cancer, summarize most recent findings on their anti-oxidative and antiapoptotic mechanisms, and discuss how this could be used in putative future therapies to target atherosclerosis and cancer.

  • impaired hepatic insulin signalling in pon2 deficient mice a novel role for the pon2 apoe axis on the macrophage inflammatory response
    Biochemical Journal, 2011
    Co-Authors: Noam Bourquard, Srinivasa T Reddy
    Abstract:

    Hepatic glucose metabolism is strongly influenced by oxidative stress and pro-inflammatory stimuli. PON2 (paraoxonase 2), an enzyme with undefined antioxidant properties, protects against atherosclerosis. PON2-deficient (PON2-def) mice have elevated hepatic oxidative stress coupled with an exacerbated inflammatory response from PON2-deficient macrophages. In the present paper, we demonstrate that PON2 deficiency is associated with inhibitory insulin-mediated phosphorylation of hepatic IRS-1 (insulin receptor substrate-1). Unexpectedly, we observed a marked improvement in the hepatic IRS-1 phosphorylation state in PON2-def/apoE (apolipoprotein E)(-/-) mice, relative to apoE(-/-) mice. Factors secreted from activated macrophage cultures derived from PON2-def and PON2-def/apoE(-/-) mice are sufficient to modulate insulin signalling in cultured hepatocytes in a manner similar to that observed in vivo. We show that the protective effect on insulin signalling in PON2-def/apoE(-/-) mice is directly associated with altered production of macrophage pro-inflammatory mediators, but not elevated intracellular oxidative stress levels. We further present evidence that modulation of the macrophage inflammatory response in PON2-def/apoE(-/-) mice is mediated by a shift in the balance of NO and ONOO(-) (peroxynitrite) formation. Our results demonstrate that PON2 plays an important role in hepatic insulin signalling and underscores the influence of macrophage-mediated inflammatory response on hepatic insulin sensitivity.

Diana M Shih - One of the best experts on this subject based on the ideXlab platform.

  • pon2 deficiency leads to increased susceptibility to diet induced obesity
    Antioxidants, 2019
    Co-Authors: Diana M Shih, Alan M. Fogelman, Aldons J Lusis, Yonghong Meng, Tamer Sallam, Laurent Vergnes, Michelle L Shu, Karen Reue, Peter Tontonoz, Srinivasa T Reddy
    Abstract:

    (1) Background: Paraoxonase 2 (PON2) is a ubiquitously expressed protein localized to endoplasmic reticulum and mitochondria. Previous studies have shown that PON2 exhibits anti-oxidant and anti-inflammatory functions, and PON2-deficient (PON2-def) mice are more susceptible to atherosclerosis. Furthermore, PON2 deficiency leads to impaired mitochondrial function. (2) Methods: In this study, we examined the susceptibility of PON2-def mice to diet-induced obesity. (3) Results: After feeding of an obesifying diet, the PON2-def mice exhibited significantly increased body weight due to increased fat mass weight as compared to the wild-type (WT) mice. The increased adiposity was due, in part, to increased adipocyte hypertrophy. PON2-def mice had increased fasting insulin levels and impaired glucose tolerance after diet-induced obesity. PON2-def mice had decreased oxygen consumption and energy expenditure. Furthermore, the oxygen consumption rate of subcutaneous fat pads from PON2-def mice was lower compared to WT mice. Gene expression analysis of the subcutaneous fat pads revealed decreased expression levels of markers for beige adipocytes in PON2-def mice. (4) Conclusions: We concluded that altered systemic energy balance, perhaps due to decreased beige adipocytes and mitochondrial dysfunction in white adipose tissue of PON2-def mice, leads to increased obesity in these mice.

  • identification of biologically active δ lactone eicosanoids as paraoxonase substrates
    Biochemical and Biophysical Research Communications, 2018
    Co-Authors: John F Teiber, Junhui Xiao, Gerald L Kramer, Seiji Ogawa, Christian Ebner, Helene Wolleb, Diana M Shih, Erick M. Carreira, Robert W Haley
    Abstract:

    Abstract The mammalian paraoxonases (PONs 1, 2 and 3) are a family of esterases that are highly conserved within and between species. They exhibit antioxidant and anti-inflammatory activities. However, their physiological function(s) and native substrates are uncertain. Previous structure-activity relationship studies demonstrate that PONs have a high specificity for lipophilic lactones, suggesting that such compounds may be representative of native substrates. This report describes the ability of PONs to hydrolyze two bioactive δ-lactones derived from arachidonic acid, 5,6-dihydroxy-eicosatrienoic acid lactone (5,6-DHTL) and cyclo-epoxycyclopentenone (cyclo-EC). Both lactones were very efficiently hydrolyzed by purified PON3. PON1 efficiently hydrolyzed 5,6-DHTL, but with a specific activity about 15-fold lower than PON3. 5,6-DHTL was a poor substrate for PON2. Cyclo-EC was a poor substrate for PON1 and not hydrolyzed by PON2. Studies with the PON inhibitor EDTA and a serine esterase inhibitor indicated that the PONs are the main contributors to hydrolysis of the lactones in human and mouse liver homogenates. Studies with homogenates from PON3 knockout mouse livers indicated that >80% of the 5,6-DHTL and cyclo-EC lactonase activities were attributed to PON3. The findings provide further insight into the structural requirements for PONs substrates and support the hypothesis that PONs, particularly PON1 and PON3, evolved to hydrolyze and regulate a class of lactone lipid mediators derived from polyunsaturated fatty acids.

  • paraoxonase 2 prevents the development of heart failure
    Free Radical Biology and Medicine, 2018
    Co-Authors: David J Kennedy, Zhili Shao, Xi Wang, Andre Klaassen Kamdar, Malory Weber, Kayla Mislick, Kathryn Kiefer, Rommel Morales, Brendan Agatisaboyle, Diana M Shih
    Abstract:

    Abstract Background Mitochondrial oxidation is a major source of reactive oxygen species (ROS) and mitochondrial dysfunction plays a central role in development of heart failure (HF). Paraoxonase 2 deficient (PON2-def) mitochondria are impaired in function. In this study, we tested whether PON2-def aggravates HF progression. Methods and results Using qPCR, immunoblotting and lactonase activity assay, we demonstrate that PON2 activity was significantly decreased in failing hearts despite increased PON2 expression. To determine the cardiac-specific function of PON2, we performed heart transplantations in which PON2-def and wild type (WT) donor hearts were implanted into WT recipient mice. Beating scores of the donor hearts, assessed at 4 weeks post-transplantation, were significantly decreased in PON2-def hearts when compared to WT donor hearts. By using a transverse aortic constriction (TAC) model, we found PON2 deficiency significantly exacerbated left ventricular remodeling and cardiac fibrosis post-TAC. We further demonstrated PON2 deficiency significantly enhanced ROS generation in heart tissues post-TAC. ROS generation was measured through dihydroethidium (DHE) using high-pressure liquid chromatography (HPLC) with a fluorescent detector. By using neonatal cardiomyocytes treated with CoCl2 to mimic hypoxia, we found PON2 deficiency dramatically increased ROS generation in the cardiomyocytes upon CoCl2 treatment. In response to a short CoCl2 exposure, cell viability and succinate dehydrogenase (SDH) activity assessed by MTT assay were significantly diminished in PON2-def cardiomyocytes compared to those in WT cardiomyocytes. PON2-def cardiomyocytes also had lower baseline SDH activity. By using adult mouse cardiomyocytes and mitochondrial ToxGlo assay, we found impaired cellular ATP generation in PON2-def cells compared to that in WT cells, suggesting that PON2 is necessary for proper mitochondrial function. Conclusion Our study suggests a cardioprotective role for PON2 in both experimental and human heart failure, which may be associated with the ability of PON2 to improve mitochondrial function and diminish ROS generation.

  • a common mutation in paraoxonase 2 results in impaired lactonase activity
    Journal of Biological Chemistry, 2009
    Co-Authors: David A Stoltz, Diana M Shih, Aldons J Lusis, Egon A Ozer, Thomas Recker, Miriam Estin, Xia Yang, Joseph Zabner
    Abstract:

    Paraoxonases (PONs) are a family of lactonases with promiscuous enzyme activity that has been implicated in multiple diseases. PON2 is intracellularly located, is the most ubiquitously expressed PON, and has the highest lactonase activity of the PON family members. Whereas some single-nucleotide polymorphisms (SNPs) in PON1 have resulted in altered enzymatic activity in serum, to date the functional consequences of SNPs on PON2 function remain unknown. We hypothesized that a common PON2 SNP would result in impaired lactonase activity. Substitution of cysteine for serine at codon 311 in recombinant PON2 resulted in normal protein production and localization but altered glycosylation and decreased lactonase activity. Moreover, we screened 200 human lung samples for the PON2 Cys311 variant and found that in vivo this mutation impaired lactonase activity. These data suggest that impaired lactonase activity may play a role in innate immunity, atherosclerosis, and other diseases associated with the PON2 311 SNP.

  • the roles of pon1 and pon2 in cardiovascular disease and innate immunity
    Current Opinion in Lipidology, 2009
    Co-Authors: Diana M Shih, Aldons J Lusis
    Abstract:

    Purpose of reviewThe paraoxonase (PON) gene family includes three members, PON1, PON2, and PON3. In-vitro and mouse studies have demonstrated that all three PONs are atheroprotective. Some, but not all, human epidemiologic studies have observed associations between PON gene polymorphisms and risk of

Dragomir I Draganov - One of the best experts on this subject based on the ideXlab platform.

  • dominant role of paraoxonases in inactivation of the pseudomonas aeruginosa quorum sensing signal n 3 oxododecanoyl l homoserine lactone
    Infection and Immunity, 2008
    Co-Authors: John F Teiber, Sven Horke, Junhui Xiao, Gerald L Kramer, Robert W Haley, Donovan C Haines, Puneet K Chowdhary, Dragomir I Draganov
    Abstract:

    Pseudomonas aeruginosa is an opportunistic bacterium which causes serious infections in immunocompromised and cystic fibrosis patients (10). As with many gram-negative bacteria, P. aeruginosa produces acyl-homoserine lactone (AHL) quorum-sensing (QS) signaling molecules termed autoinducers which allow the single-celled organisms to coordinate their actions (36). N-(3-Oxododecanoyl)-l-homoserine lactone (3OC12-HSL) is a key autoinducer synthesized by P. aeruginosa which regulates the expression of extracellular virulence factors and biofilm formation (5, 36). Rats and mice experimentally infected with P. aeruginosa mutants deficient in the ability to produce or respond to 3OC12-HSL exhibited significantly diminished lung pathology, bacterial dissemination, and morbidity and accelerated bacterial clearance compared to animals infected with wild-type bacteria, demonstrating the importance of 3OC12-HSL for P. aeruginosa pathogenicity (14, 21, 27, 31, 40). 3OC12-HSL also has an array of immunomodulatory effects on eukaryotic cells, including the induction of apoptosis, inhibition of leukocyte proliferation, activation of neutrophils and macrophages, and induction of proinflammatory mediators (7, 15, 34, 37, 39, 43). Recently, it was shown that a number of mammalian cell lines were able to inactive 3OC12-HSL (5), providing a possible mechanism for reduction of bacterial virulence. Mammalian paraoxonases (PONs) are a unique, highly conserved family of calcium-dependent esterases consisting of PON1, PON2, and PON3 (8). Human PON1 and PON3 are synthesized predominantly in the liver from where PON1 and some PON3 are secreted into the blood and associated with high-density lipoproteins (HDL) (29). PON2 is not in serum but is expressed in many tissues and cell types (8, 25). PONs exhibit antioxidative properties and afford protection from atherosclerosis in mouse models; however, the mechanisms by which they mediate these properties are not yet established (1, 16, 24, 32, 33). PONs hydrolyze a broad range of esters, including phosphotriesters, arylesters, and lactones, and have overlapping, but also distinct, substrate specificities (9). Although the physiological function(s) and natural substrates for the PONs are uncertain, accumulating evidence indicates that the lactonase activity of the PONs may be its natural function (9, 17). Serum PON1 hydrolyzes the lactone ring of 3OC12-HSL (26) and the lactonase activity of the PONs extends over a number of AHL QS compounds with various acyl chain lengths (9, 38). Sera from PON1 knockout (PON1−/−) mice are deficient in 3OC12-HSL hydrolytic activity, but surprisingly, PON1−/− mice had a higher rate of survival than wild-type mice after intraperitoneal injection of the bacterium P. aeruginosa (26). PON2 and PON3 were shown to be up-regulated in the PON1−/− mouse airway epithelium, and it was suggested that this up-regulation may lead to increased inactivation of 3OC12-HSL. However, the possible up-regulation and contribution of other enzymes toward 3OC12-HSL inactivation in this model were not investigated. For murine tracheal epithelial cells, PON2 was shown to be important for the inactivation of 3OC12-HSL by demonstrating that the cell lysates from PON2-deficient mice had an impaired ability to hydrolyze 3OC12-HSL and that P. aeruginosa QS was enhanced in these epithelial cell cultures (38). Interestingly, in intact epithelial cells there was no difference in the rates of 3OC12-HSL inactivation between the wild-type and PON2-deficient cells. Thus, the relative importance of the role that PON2 plays in the intact cells is not clear, and other inactivation pathways, PON or non-PON, may be important for 3OC12-HSL inactivation in these cells. Mammals express a broad range of enzymes, such as carboxylesterases, amidases, acylases, proteases, oxidases, and reductases, which could potentially inactive 3OC12-HSL, as well as other AHLs, and the importance of PON-mediated inactivation of 3OC12-HSL relative to other enzymatic pathways is not known. Therefore, the aim of this study was to determine if there are other mammalian enzymes which may inactivate 3OC12-HSL and to evaluate the contribution of the PONs to 3OC12-HSL metabolism. We found that the human PONs, particularly PON2, could efficiently hydrolyze 3OC12-HSL. PONs were the major enzymes inactivating this lactone in human and mouse serum, mouse lung and liver homogenates, and cultured human cell lysates. Thus, our study suggests that the PONs, especially PON2, may represent a key defense mechanism against the P. aeruginosa QS autoinducer 3OC12-HSL.

  • human paraoxonases pon1 pon2 and PON3 are lactonases with overlapping and distinct substrate specificities
    Journal of Lipid Research, 2005
    Co-Authors: Dragomir I Draganov, John F Teiber, Audrey Speelman, Yoichi Osawa, Roger K Sunahara
    Abstract:

    The paraoxonase (PON) gene family in humans has three members, PON1, PON2, and PON3. Their physiological role(s) and natural substrates are uncertain. We developed a baculovirus-mediated expression system, suitable for all three human PONs, and optimized procedures for their purification. The recombinant PONs are glycosylated with high-mannose-type sugars, which are important for protein stability but are not essential for their enzymatic activities. Enzymatic characterization of the purified PONs has revealed them to be lactonases/lactonizing enzymes, with some overlapping substrates (e.g., aromatic lactones), but also to have distinctive substrate specificities. All three PONs metabolized very efficiently 5-hydroxy-eicosatetraenoic acid 1,5-lactone and 4-hydroxy-docosahexaenoic acid, which are products of both enzymatic and nonenzymatic oxidation of arachidonic acid and docosahexaenoic acid, respectively, and may represent the PONs' endogenous substrates. Organophosphates are hydrolyzed almost exclusively by PON1, whereas bulky drug substrates such as lovastatin and spironolactone are hydrolyzed only by PON3. Of special interest is the ability of the human PONs, especially PON2, to hydrolyze and thereby inactivate N-acyl-homoserine lactones, which are quorum-sensing signals of pathogenic bacteria. None of the recombinant PONs protected low density lipoprotein against copper-induced oxidation in vitro.

  • Lactonase and lactonizing activities of human serum paraoxonase (PON1) and rabbit serum PON3.
    Biochemical pharmacology, 2003
    Co-Authors: John F Teiber, Dragomir I Draganov
    Abstract:

    Abstract Human paraoxonase (PON1) was previously shown to hydrolyze over 30 different lactones (cyclic esters). In the present study purified human PON1 was found to catalyze the reverse reaction (lactonization) of a broad range of hydroxy acids. Hydroxy acid lactonization or lactone hydrolysis is catalyzed until equilibrium between the open and closed forms is reached. Lactonization by PON1 was calcium-dependent, had a pH optimum of 5.5–6 and could be stimulated with dilauroylphosphatidylcholine. Rabbit serum PON3 and a serine esterase in mouse plasma, presumably a carboxylesterase, also catalyzed hydroxy acid lactonization. Two endogenous oxidized unsaturated fatty acids, (±)4-hydroxy-5 E ,7 Z ,10 Z ,13 Z ,16 Z ,19 Z -docosahexaenoic acid (4-HDoHE) and (±)5-hydroxy-6 E ,8 Z ,11 Z ,14 Z -eicosatetraenoic acid (5-HETE) lactone, were very efficiently lactonized and hydrolyzed, respectively, by PON1. Human and mouse plasma samples also catalyzed 4-HDoHE lactonization and 5-HETE lactone hydrolysis. Studies with the PON1 inhibitor EDTA and the serine esterase inhibitor phenylmethylsulfonylfluoride suggest that about 80–95% of both activities can be attributed to PON1 in the human samples. In the mouse sample, PON1 accounted for about 30% of the 4-HDoHE lactonizing activity and 72% of the 5-HETE lactonase activity. Our results demonstrate that PON1 can lactonize the hydroxy acid form of its lactone substrates and that reversible hydrolysis of lactones may be a property of lactonases that is not generally considered. Also, the high activity of PON1 towards 4-HDoHE and 5-HETE lactone suggests that oxidized eicosanoids and docosanoids may be important physiological substrates for PON1.

  • rabbit serum paraoxonase 3 PON3 is a high density lipoprotein associated lactonase and protects low density lipoprotein against oxidation
    Journal of Biological Chemistry, 2000
    Co-Authors: Dragomir I Draganov, Philip L Stetson, Catherine E Watson, Scott S Billecke
    Abstract:

    The paraoxonase gene family contains at least three members: PON1, PON2, and PON3. The physiological roles of the corresponding gene products are still uncertain. Until recently, only the serum paraoxonase/arylesterase (PON1) had been purified and characterized. Here we report the purification, cloning, and characterization of rabbit serum PON3. PON3 is a 40-kDa protein associated with the high density lipoprotein fraction of serum. In contrast to PON1, PON3 has very limited arylesterase and no paraoxonase activities but rapidly hydrolyzes lactones such as statin prodrugs (e.g. lovastatin). These differences facilitated the complete separation of PON3 from PON1 during purification. PON3 hydrolyzes aromatic lactones and 5- or 6-member ring lactones with aliphatic substituents but not simple lactones or those with polar substituents. We cloned PON3 from total rabbit liver RNA and expressed it in mammalian 293T/17 cells. The recombinant PON3 has the same apparent molecular mass and substrate specificity as the enzyme purified from serum. Rabbit serum PON3 is more efficient than rabbit PON1 in protecting low density lipoprotein from copper-induced oxidation. This is the first report that identifies a second PON enzyme in mammalian serum and the first to describe an enzymatic activity for PON3.

Clement E Furlong - One of the best experts on this subject based on the ideXlab platform.

  • paraoxonase 2 pon2 in brain and its potential role in neuroprotection
    Neurotoxicology, 2014
    Co-Authors: Lucio G Costa, Rian De Laat, Khoi Dao, Claudia Pellacani, Toby B Cole, Clement E Furlong
    Abstract:

    Paraoxonase 2 (PON2) is a member of a gene family which also includes the more studied PON1, as well as PON3. PON2 is unique among the three PONs, as it is expressed in brain tissue. PON2 is a lactonase and displays anti-oxidant and anti-inflammatory properties. PON2 levels are highest in dopaminergic regions (e.g. striatum), are higher in astrocytes than in neurons, and are higher in brain and peripheral tissues of female mice than male mice. At the sub-cellular level, PON2 localizes primarily in mitochondria, where it scavenges superoxides. Lack of PON2 (as in PON2−/− mice), or lower levels of PON2 (as in male mice compared to females) increases susceptibility to oxidative stress-induced toxicity. Estradiol increases PON2 expression in vitro and in vivo, and provides neuroprotection against oxidative stress. Such neuroprotection is not present in CNS cells from PON2−/− mice. Similar results are also found with the polyphenol quercetin. PON2, given its cellular localization and antioxidant and anti-inflammatory actions, may represent a relevant enzyme involved in neuroprotection, and may represent a novel target for neuroprotective strategies. Its differential expression in males and females may explain gender differences in the incidence of various diseases, including neurodevelopmental, neurological, and neurodegenerative diseases.

  • gender differences in brain susceptibility to oxidative stress are mediated by levels of paraoxonase 2 expression
    Free Radical Biology and Medicine, 2013
    Co-Authors: Gennaro Giordano, Toby B Cole, Clement E Furlong, L Tait, Terrance J Kavanagh, Lucio G Costa
    Abstract:

    Paraoxonase 2 (PON2), a member of a gene family that also includes PON1 and PON3, is expressed in most tissues, including the brain. In mouse brain, PON2 levels are highest in dopaminergic areas (e.g., striatum) and are higher in astrocytes than in neurons. PON2 is primarily located in mitochondria and exerts a potent antioxidant effect, protecting mouse CNS cells against oxidative stress. The aim of this study was to characterize PON2 expression and functions in the brains of male and female mice. Levels of PON2 (protein, mRNA, and lactonase activity) were higher in brain regions and cells of female mice. Astrocytes and neurons from male mice were significantly more sensitive (by 3- to 4-fold) to oxidative stress-induced toxicity than the same cells from female mice. Glutathione levels did not differ between genders. Importantly, no significant gender differences in susceptibility to the same oxidants were seen in cells from PON2(-/-) mice. Treatment with estradiol induced a time- and concentration-dependent increase in the levels of PON2 protein and mRNA in male (4.5-fold) and female (1.8-fold) astrocytes, which was dependent on activation of estrogen receptor-α. In ovariectomized mice, PON2 protein and mRNA were decreased to male levels in brain regions and in liver. Estradiol protected astrocytes from wild-type mice against oxidative stress-induced neurotoxicity, but did not protect cells from PON2(-/-) mice. These results suggest that PON2 is a novel major intracellular factor that protects CNS cells against oxidative stress and confers gender-dependent susceptibility to such stress. The lower expression of PON2 in males may have broad ramifications for susceptibility to diseases involving oxidative stress, including neurodegenerative diseases.

  • additional common polymorphisms in the pon gene cluster predict pon1 activity but not vascular disease
    Journal of Lipids, 2012
    Co-Authors: Daniel S Kim, Clement E Furlong, Rebecca J Richter, Jane E Ranchalis, Amber Burt, Julieann K Marshall, Jason F Eintracht, Elisabeth A Rosenthal, Gail P Jarvik
    Abstract:

    Background. Paraoxonase 1 (PON1) enzymatic activity has been consistently predictive of cardiovascular disease, while the genotypes at the four functional polymorphisms at PON1 have not. The goal of this study was to identify additional variation at the PON gene cluster that improved prediction of PON1 activity and determine if these variants predict carotid artery disease (CAAD). Methods. We considered 1,328 males in a CAAD cohort. 51 tagging single-nucleotide polymorphisms (tag SNPs) across the PON cluster were evaluated to determine their effects on PON1 activity and CAAD status. Results. Six SNPs (four in PON1 and one each in PON2/3) predicted PON1 arylesterase (AREase) activity, in addition to the four previously known functional SNPs. In total, the 10 SNPs explained 30.1% of AREase activity, 5% of which was attributable to the six identified predictive SNPs. We replicate rs854567 prediction of 2.3% of AREase variance, the effects of rs3917510, and a PON3 haplotype that includes rs2375005. While AREase activity strongly predicted CAAD, none of the 10 SNPs predicting AREase predicted CAAD. Conclusions. This study identifies new genetic variants that predict additional PON1 AREase activity. Identification of SNPs associated with PON1 activity is required when evaluating the many phenotypes associated with genetic variation near PON1.

  • paraoxonase 2 pon2 in the mouse central nervous system a neuroprotective role
    Toxicology and Applied Pharmacology, 2011
    Co-Authors: Gennaro Giordano, Lucio G Costa, Toby B Cole, Clement E Furlong
    Abstract:

    The aims of this study were to characterize the expression of paraoxonase 2 (PON2) in mouse brain and to assess its antioxidant properties. PON2 levels were highest in the lung, intestine, heart and liver, and lower in the brain; in all tissues, PON2 expression was higher in female than in male mice. PON2 knockout [PON2(-/-)] mice did not express any PON2, as expected. In the brain, the highest levels of PON2 were found in the substantia nigra, the nucleus accumbens and the striatum, with lower levels in the cerebral cortex, hippocampus, cerebellum and brainstem. A similar regional distribution of PON2 activity (measured by dihydrocoumarin hydrolysis) was also found. PON3 was not detected in any brain area, while PON1 was expressed at very low levels, and did not show any regional difference. PON2 levels were higher in astrocytes than in neurons isolated from all brain regions, and were highest in cells from the striatum. PON2 activity and mRNA levels followed a similar pattern. Brain PON2 levels were highest around birth, and gradually declined. Subcellular distribution experiments indicated that PON2 is primarily expressed in microsomes and in mitochondria. The toxicity in neurons and astrocytes of agents known to cause oxidative stress (DMNQ and H(2)O(2)) was higher in cells from PON2(-/-) mice than in the same cells from wild-type mice, despite similar glutathione levels. These results indicate that PON2 is expressed in the brain, and that higher levels are found in dopaminergic regions such as the striatum, suggesting that this enzyme may provide protection against oxidative stress-mediated neurotoxicity.

  • determination of paraoxonase 1 status without the use of toxic organophosphate substrates
    Circulation-cardiovascular Genetics, 2008
    Co-Authors: Rebecca J Richter, Gail P Jarvik, Clement E Furlong
    Abstract:

    Paraoxonase 1 ( PON1 ) is a member of a tandem 3-gene family localized on human chromosome 7q21-22.1 High-density lipoprotein-associated PON1 2,3 and PON34,5 are synthesized primarily in the liver, whereas PON2 is ubiquitously expressed.1 PON1 was initially characterized and named for its ability to hydrolyze paraoxon, the toxic oxon metabolite of parathion.6 Although Aldridge6 proposed in 1953 that serum paraoxonase (POase) and arylesterase (AREase) activities were carried out by the same enzyme, controversy about 1 versus 2 enzymes persisted for many years, resulting in a reclassification of POase/AREase from EC 3.1.1.2 to EC 3.1.8.1 for PON1 as an example of an organophosphorus (OP) hydrolase.7 The controversy was finally settled when Sorenson et al8 demonstrated both activities in recombinant PON1 . However, the revised nomenclature remains in place. Early studies of plasma PON1 found a large variability of POase activity among different species and in different tissues.6 Serum POase activity distribution studies in human populations revealed an activity polymorphism of high versus low POase activity. Studies on the polymorphic distribution of PON1 in human populations using a variety of different assays revealed bi or trimodal distributions of plasma POase activity (reviewed in Ref. 9). Editorial see p 79 Our initial characterization of the human PON1 cDNA clones revealed 2 coding region polymorphisms Q192R and L55 M.10 Subsequently, it was shown that the Q192R polymorphism determined high versus low rates of paraoxon hydrolysis by the enzyme, with the PON1 R192 alloform specifying high activity.11,12 After the demonstration that high-density lipoprotein-associated PON1 was implicated in reducing low-density lipoprotein13 and high-density lipoprotein14 oxidation, epidemiological studies were undertaken to explore the possible role of genetic variability of PON1 in cardiovascular disease15 (reviewed in Ref. 16). Several meta-analyses of studies that examined only …