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Huang H, Liao J, Zheng X, Chen Y, Ren H. Low-level free nitrous acid efficiently inhibits the conjugative transfer of antibiotic resistance by altering intracellular ions and disabling transfer apparatus. WATER RESEARCH 2019; 158:383-391. [PMID: 31059932 DOI: 10.1016/j.watres.2019.04.046] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
Recently, the dissemination of antibiotic resistance genes (ARGs) via plasmid-mediated conjugation has been reported to be facilitated by a series of contaminants. This has highlighted potential challenges to the effective control of this principal mode of horizontal transfer. In the present study, we found that low levels (<0.02 mgN/L) of free nitrous acid (FNA) remarkably inhibited (over 90%) the conjugative transfer of plasmid RP4, a model broad-host-range plasmid, between Escherichia coli. The antimicrobial role of FNA at the applied dosages was firstly ruled out, since no dramatic reductions in viabilities of donor or recipient were observed. Instead, FNA appeared to reduce the available intracellular free Mg2+, which was confirmed to be triggered by the liberation of intracellular Fe2+. These alterations in intracellular Mg2+ and Fe2+ concentrations were found to significantly limit the available energy for conjugative transfer through suppression of glycolysis by decreasing the activities of glycogen phosphorylase and glyceraldehyde-3-phosphate dehydrogenase and also by diverting the glycolytic flux into the pentose phosphate pathway via activation of glucose-6-phosphate dehydrogenase towards the generation of NADPH rather than ATP. Moreover, RP4-encoding genes responsible for DNA transfer and replication (traI, traJ and trfAp), coupling (traG) and mating pair formation (traF and trbBp) were all significantly down-regulated after FNA treatment, indicating that the transfer apparatus required for plasmid processing and delivery was deactivated. By validating the inhibitory effects of FNA on conjugation in real wastewater, this study highlights a promising method for controlling the dissemination of ARGs in systems such as wastewater treatment plants.
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Affiliation(s)
- Haining Huang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Junqi Liao
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Xiong Zheng
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Yinguang Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210093, Jiangsu, PR China
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Post S, Karashchuk G, Wade JD, Sajid W, De Meyts P, Tatar M. Drosophila Insulin-Like Peptides DILP2 and DILP5 Differentially Stimulate Cell Signaling and Glycogen Phosphorylase to Regulate Longevity. Front Endocrinol (Lausanne) 2018; 9:245. [PMID: 29892262 PMCID: PMC5985746 DOI: 10.3389/fendo.2018.00245] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/02/2018] [Indexed: 01/08/2023] Open
Abstract
Insulin and IGF signaling (IIS) is a complex system that controls diverse processes including growth, development, metabolism, stress responses, and aging. Drosophila melanogaster IIS is propagated by eight Drosophila insulin-like peptides (DILPs), homologs of both mammalian insulin and IGFs, with various spatiotemporal expression patterns and functions. DILPs 1-7 are thought to act through a single Drosophila insulin/IGF receptor, InR, but it is unclear how the DILPs thereby mediate a range of physiological phenotypes. We determined the distinct cell signaling effects of DILP2 and DILP5 stimulation upon Drosophila S2 cells. DILP2 and DILP5 induced similar transcriptional patterns but differed in signal transduction kinetics. DILP5 induced sustained phosphorylation of Akt, while DILP2 produced acute, transient Akt phosphorylation. Accordingly, we used phosphoproteomic analysis to identify distinct patterns of non-genomic signaling induced by DILP2 and DILP5. Across all treatments and replicates, 5,250 unique phosphopeptides were identified, representing 1,575 proteins. Among these peptides, DILP2, but not DILP5, dephosphorylated Ser15 on glycogen phosphorylase (GlyP), and DILP2, but not DILP5, was subsequently shown to repress enzymatic GlyP activity in S2 cells. The functional consequences of this difference were evaluated in adult Drosophila dilp mutants: dilp2 null adults have elevated GlyP enzymatic activity relative to wild type, while dilp5 mutants have reduced GlyP activity. In flies with intact insulin genes, GlyP overexpression extended lifespan in a Ser15 phosphorylation-dependent manner. In dilp2 mutants, that are otherwise long-lived, longevity was repressed by expression of phosphonull GlyP that is enzymatically inactive. Overall, DILP2, unlike DILP5, signals to affect longevity in part through its control of phosphorylation to deactivate glycogen phosphorylase, a central modulator of glycogen storage and gluconeogenesis.
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Affiliation(s)
- Stephanie Post
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, United States
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States
- *Correspondence: Stephanie Post, ; Marc Tatar,
| | - Galina Karashchuk
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States
| | - John D. Wade
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
- School of Chemistry, University of Melbourne, Melbourne, VIC, Australia
| | | | - Pierre De Meyts
- Department of Cell Signalling, de Duve Institute, Brussels, Belgium
- Department of Stem Cell Research Novo Nordisk A/S, Måløv, Denmark
| | - Marc Tatar
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States
- *Correspondence: Stephanie Post, ; Marc Tatar,
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3
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Tolosa L, Jiménez N, Pérez G, Castell JV, Gómez-Lechón MJ, Donato MT. Customised in vitro model to detect human metabolism-dependent idiosyncratic drug-induced liver injury. Arch Toxicol 2017; 92:383-399. [PMID: 28762043 PMCID: PMC5773651 DOI: 10.1007/s00204-017-2036-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 07/12/2017] [Indexed: 12/17/2022]
Abstract
Drug-induced liver injury (DILI) has a considerable impact on human health and is a major challenge in drug safety assessments. DILI is a frequent cause of liver injury and a leading reason for post-approval drug regulatory actions. Considerable variations in the expression levels of both cytochrome P450 (CYP) and conjugating enzymes have been described in humans, which could be responsible for increased susceptibility to DILI in some individuals. We herein explored the feasibility of the combined use of HepG2 cells co-transduced with multiple adenoviruses that encode drug-metabolising enzymes, and a high-content screening assay to evaluate metabolism-dependent drug toxicity and to identify metabolic phenotypes with increased susceptibility to DILI. To this end, HepG2 cells with different expression levels of specific drug-metabolism enzymes (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, GSTM1 and UGT2B7) were exposed to nine drugs with reported hepatotoxicity. A panel of pre-lethal mechanistic parameters (mitochondrial superoxide production, mitochondrial membrane potential, ROS production, intracellular calcium concentration, apoptotic nuclei) was used. Significant differences were observed according to the level of expression and/or the combination of several drug-metabolism enzymes in the cells created ad hoc according to the enzymes implicated in drug toxicity. Additionally, the main mechanisms implicated in the toxicity of the compounds were also determined showing also differences between the different types of cells employed. This screening tool allowed to mimic the variability in drug metabolism in the population and showed a highly efficient system for predicting human DILI, identifying the metabolic phenotypes associated with increased DILI risk, and indicating the mechanisms implicated in their toxicity.
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Affiliation(s)
- Laia Tolosa
- Unidad de Hepatología Experimental, Torre A, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Av Fernando Abril Martorell 106, 46026, Valencia, Spain.
| | - Nuria Jiménez
- Unidad de Hepatología Experimental, Torre A, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Av Fernando Abril Martorell 106, 46026, Valencia, Spain
| | - Gabriela Pérez
- Unidad de Hepatología Experimental, Torre A, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Av Fernando Abril Martorell 106, 46026, Valencia, Spain
| | - José V Castell
- Unidad de Hepatología Experimental, Torre A, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Av Fernando Abril Martorell 106, 46026, Valencia, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Valencia, 46010, Valencia, Spain
| | - M José Gómez-Lechón
- Unidad de Hepatología Experimental, Torre A, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Av Fernando Abril Martorell 106, 46026, Valencia, Spain
| | - M Teresa Donato
- Unidad de Hepatología Experimental, Torre A, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Av Fernando Abril Martorell 106, 46026, Valencia, Spain. .,Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Valencia, 46010, Valencia, Spain.
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4
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DeCarlo AA, Whitelock JM. The Role of Heparan Sulfate and Perlecan in Bone-regenerative Procedures. J Dent Res 2016; 85:122-32. [PMID: 16434729 DOI: 10.1177/154405910608500203] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Tissue engineering, grafting procedures, regeneration, and tissue remodeling are developing therapeutic modalities with great potential medical value, but these regenerative modalities are not as effective or predictable as clinicians and patients would like. Greater understanding of growth factors, cytokines, extracellular matrix molecules, and their roles in cell-mediated healing processes have made these regenerative therapies more clinically viable and will continue advancing the fields of tissue engineering and grafting. However, millions of oral and non-oral bone-grafting procedures are performed annually, and only a small percentage yield the most desirable results. Here we review the heparan-sulfate-decorated extracellular biomolecule named perlecan and the research relating to its potential as an adjunct in bone-regenerative procedures. The review includes an overview of bone graft substitutes and biological adjuncts to bone-regenerative procedures in medicine as they apply to periodontal disease, alveolar ridge augmentation, and barrier membrane therapy. Perlecan is discussed as a potential biological adjunct in terms of growth factor sequestration and delivery, and promoting cell adhesion, proliferation, differentiation, and angiogenesis. Further, we propose delivery and application schemes for perlecan and/or its domains in bone-regenerative procedures, with particular emphasis on its heparan-sulfate-decorated domain I. The perlecan molecule, with its heparan sulfate glycosylation, may provide a multi-faceted approach for the delivery of a more comprehensive stimulus than other single potential adjuncts currently available for bone-regenerative procedures.
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Affiliation(s)
- A A DeCarlo
- Agenta Biotechnologies, Inc., OADI Technology Center, Birmingham, AL 35211, USA.
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5
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Suchanek AL, Salati LM. Construction and evaluation of an adenoviral vector for the liver-specific expression of the serine/arginine-rich splicing factor, SRSF3. Plasmid 2015; 82:1-9. [PMID: 26241824 DOI: 10.1016/j.plasmid.2015.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 07/24/2015] [Accepted: 07/27/2015] [Indexed: 01/09/2023]
Abstract
Serine/arginine-rich splicing factor-3 (SRSF3), alternatively known as SRp20, is a member of the highly-conserved SR protein family of mRNA splicing factors. SRSF3 generally functions as an enhancer of mRNA splicing by binding to transcripts in a sequence-specific manner to both recruit and stabilize the binding of spliceosomal components to the mRNA. In liver, expression of SRSF3 is relatively low and its activity is increased in response to insulin and feeding a high carbohydrate diet. We sought to over-express SRSF3 in primary rat hepatocytes to identify regulatory targets. A standard adenoviral shuttle vector system containing an epitope-tagged SRSF3 under the transcriptional control of the CMV promoter could not be used to produce infectious adenoviral particles. SRSF3 over-expression in the packaging cell line prevented the production of infectious adenovirus particles by interfering with the viral splicing program. To circumvent this issue, SRSF3 expression from the shuttle vector was blocked by placing its expression under the control of the liver-specific albumin promoter. In this system, the FLAG-SRSF3 transgene is only expressed in the target cells (hepatocytes) but not in the packaging cell line. An additional benefit of the albumin promoter is that expression of the transgene does not require the addition of hormones or antibiotics to drive SRSF3 expression in the hepatocytes. Robust expression of FLAG-SRSF3 protein is detected in both HepG2 cells and primary rat hepatocytes infected with adenovirus prepared from this new shuttle vector. Furthermore, abundances of several known and suspected mRNA targets of SRSF3 action are increased in response to over-expression using this virus. This report details the construction of the albumin promoter-driven adenoviral shuttle vector, termed pmAlbAd5-FLAG.SRSF3, that can be used to generate functional adenovirus to express FLAG-SRSF3 specifically in liver. This vector would be suitable for over-expression of other splicing factors that could inhibit virus production. In addition, this vector would allow only liver-specific expression of other cargo genes when used in a whole-animal paradigm.
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Affiliation(s)
- Amanda L Suchanek
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV 26506, United States
| | - Lisa M Salati
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV 26506, United States.
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6
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Benet M, Jover R, Bort R. Transfection of Primary Hepatocytes with Liver-Enriched Transcription Factors Using Adenoviral Vectors. Methods Mol Biol 2015; 1250:213-221. [PMID: 26272145 DOI: 10.1007/978-1-4939-2074-7_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Primary cultured hepatocytes are probably the best model to study endogenous metabolic pathways, toxicity, or drug metabolism. Many of these studies require expression of ectopic genes. It would be desirable to use a method of transfection that allows dose-response studies, high efficiency of transfection, and the possibility to express several genes at the same time. Adenoviral vectors fulfill these requirements, becoming a valuable tool for primary hepatocyte transfection. Moreover, they are easy to generate and do not require a high level of biocontainment. In the present chapter, we describe the generation, cloning, amplification, and purification of an adenoviral vector capable of infecting primary cultured hepatocytes. This recombinant adenovirus induces robust expression of the protein of interest in hepatocytes within a wide range of doses.
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Affiliation(s)
- Marta Benet
- Unidad de Hepatología Experimental-CIBERehd, Instituto de Investigación Sanitaria La Fe, Valencia, Spain
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7
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Pisonero-Vaquero S, García-Mediavilla MV, Jorquera F, Majano PL, Benet M, Jover R, González-Gallego J, Sánchez-Campos S. Modulation of PI3K-LXRα-dependent lipogenesis mediated by oxidative/nitrosative stress contributes to inhibition of HCV replication by quercetin. J Transl Med 2014; 94:262-74. [PMID: 24492281 DOI: 10.1038/labinvest.2013.156] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 11/28/2013] [Accepted: 12/23/2013] [Indexed: 02/07/2023] Open
Abstract
There is experimental evidence that some antioxidant flavonoids show therapeutic potential in the treatment of hepatitis C through inhibition of hepatitis C virus (HCV) replication. We examined the effect of treatment with the flavonols quercetin and kaempferol, the flavanone taxifolin and the flavone apigenin on HCV replication efficiency in an in vitro model. While all flavonoids studied were able to reduce viral replication at very low concentrations (ranging from 0.1 to 5 μM), quercetin appeared to be the most effective inhibitor of HCV replication, showing a marked anti-HCV activity in replicon-containing cells when combined with interferon (IFN)α. The contribution of oxidative/nitrosative stress and lipogenesis modulation to inhibition of HCV replication by quercetin was also examined. As expected, quercetin decreased HCV-induced reactive oxygen and nitrogen species (ROS/RNS) generation and lipoperoxidation in replicating cells. Quercetin also inhibited liver X receptor (LXR)α-induced lipid accumulation in LXRα-overexpressing and replicon-containing Huh7 cells. The mechanism underlying the LXRα-dependent lipogenesis modulatory effect of quercetin in HCV-replicating cells seems to involve phosphatidylinositol 3-kinase (PI3K)/AKT pathway inactivation. Thus, inhibition of the PI3K pathway by LY294002 attenuated LXRα upregulation and HCV replication mediated by lipid accumulation, showing an additive effect when combined with quercetin. Inactivation of the PI3K pathway by quercetin may contribute to the repression of LXRα-dependent lipogenesis and to the inhibition of viral replication induced by the flavonol. Combined, our data suggest that oxidative/nitrosative stress blockage and subsequent modulation of PI3K-LXRα-mediated lipogenesis might contribute to the inhibitory effect of quercetin on HCV replication.
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Affiliation(s)
| | - María V García-Mediavilla
- 1] Institute of Biomedicine (IBIOMED), University of León, León, Spain [2] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
| | - Francisco Jorquera
- 1] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain [2] Department of Gastroenterology, Complejo Asistencial Universitario de León, León, Spain
| | - Pedro L Majano
- 1] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain [2] Molecular Biology Unit, Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria Princesa (IP), Madrid, Spain
| | - Marta Benet
- 1] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain [2] Experimental Hepatology Unit, IIS Hospital La Fe, Valencia, Spain
| | - Ramiro Jover
- 1] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain [2] Experimental Hepatology Unit, IIS Hospital La Fe, Valencia, Spain [3] Department of Biochemistry and Molecular Biology, University of Valencia, Valencia, Spain
| | - Javier González-Gallego
- 1] Institute of Biomedicine (IBIOMED), University of León, León, Spain [2] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
| | - Sonia Sánchez-Campos
- 1] Institute of Biomedicine (IBIOMED), University of León, León, Spain [2] Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
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8
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Zins K, Pomyje J, Hofer E, Abraham D, Lucas T, Aharinejad S. Egr-1 upregulates Siva-1 expression and induces cardiac fibroblast apoptosis. Int J Mol Sci 2014; 15:1538-53. [PMID: 24451137 PMCID: PMC3907885 DOI: 10.3390/ijms15011538] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 12/21/2013] [Accepted: 01/13/2014] [Indexed: 12/24/2022] Open
Abstract
The early growth response transcription factor Egr-1 controls cell specific responses to proliferation, differentiation and apoptosis. Expression of Egr-1 and downstream transcription is closely controlled and cell specific upregulation induced by processes such as hypoxia and ischemia has been previously linked to multiple aspects of cardiovascular injury. In this study, we showed constitutive expression of Egr-1 in cultured human ventricular cardiac fibroblasts, used adenoviral mediated gene transfer to study the effects of continuous Egr-1 overexpression and studied downstream transcription by Western blotting, immunohistochemistry and siRNA transfection. Apoptosis was assessed by fluorescence microscopy and flow cytometry in the presence of caspase inhibitors. Overexpression of Egr-1 directly induced apoptosis associated with caspase activation in human cardiac fibroblast cultures in vitro assessed by fluorescence microscopy and flow cytometry. Apoptotic induction was associated with a caspase activation associated loss of mitochondrial membrane potential and transient downstream transcriptional up-regulation of the pro-apoptotic gene product Siva-1. Suppression of Siva-1 induction by siRNA partially reversed Egr-1 mediated loss of cell viability. These findings suggest a previously unknown role for Egr-1 and transcriptional regulation of Siva-1 in the control of cardiac accessory cell death.
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Affiliation(s)
- Karin Zins
- Laboratory for Molecular Cellular Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna A-1090, Austria.
| | - Jiri Pomyje
- Molecular Vascular Biology, Department of Vascular Biology and Thrombosis Research, Vienna Competence Center, Vienna Medical University, Vienna A-1090, Austria.
| | - Erhard Hofer
- Molecular Vascular Biology, Department of Vascular Biology and Thrombosis Research, Vienna Competence Center, Vienna Medical University, Vienna A-1090, Austria.
| | - Dietmar Abraham
- Laboratory for Molecular Cellular Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna A-1090, Austria.
| | - Trevor Lucas
- Laboratory for Molecular Cellular Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna A-1090, Austria.
| | - Seyedhossein Aharinejad
- Laboratory for Molecular Cellular Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna A-1090, Austria.
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9
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Lahoz A, Vilà MR, Fabre M, Miquel JM, Rivas M, Maines J, Castell JV, Gómez-Lechón MJ. An in vitro tool to assess cytochrome P450 drug biotransformation-dependent cytotoxicity in engineered HepG2 cells generated by using adenoviral vectors. Toxicol In Vitro 2013; 27:1410-5. [DOI: 10.1016/j.tiv.2012.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 07/31/2012] [Accepted: 08/02/2012] [Indexed: 10/28/2022]
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Tolosa L, Gómez-Lechón MJ, Pérez-Cataldo G, Castell JV, Donato MT. HepG2 cells simultaneously expressing five P450 enzymes for the screening of hepatotoxicity: identification of bioactivable drugs and the potential mechanism of toxicity involved. Arch Toxicol 2013; 87:1115-27. [DOI: 10.1007/s00204-013-1012-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 01/17/2013] [Indexed: 11/30/2022]
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11
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Guzmán C, Benet M, Pisonero-Vaquero S, Moya M, García-Mediavilla MV, Martínez-Chantar ML, González-Gallego J, Castell JV, Sánchez-Campos S, Jover R. The human liver fatty acid binding protein (FABP1) gene is activated by FOXA1 and PPARα; and repressed by C/EBPα: Implications in FABP1 down-regulation in nonalcoholic fatty liver disease. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:803-18. [PMID: 23318274 DOI: 10.1016/j.bbalip.2012.12.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/22/2012] [Accepted: 12/27/2012] [Indexed: 01/24/2023]
Abstract
Liver fatty acid binding protein (FABP1) prevents lipotoxicity of free fatty acids and regulates fatty acid trafficking and partition. Our objective is to investigate the transcription factors controlling the human FABP1 gene and their regulation in nonalcoholic fatty liver disease (NAFLD). Adenovirus-mediated expression of multiple transcription factors in HepG2 cells and cultured human hepatocytes demonstrated that FOXA1 and PPARα are among the most effective activators of human FABP1, whereas C/EBPα is a major dominant repressor. Moreover, FOXA1 and PPARα induced re-distribution of FABP1 protein and increased cytoplasmic expression. Reporter assays demonstrated that the major basal activity of the human FABP1 promoter locates between -96 and -229bp, where C/EBPα binds to a composite DR1-C/EBP element. Mutation of this element at -123bp diminished basal reporter activity, abolished repression by C/EBPα and reduced transactivation by HNF4α. Moreover, HNF4α gene silencing by shRNA in HepG2 cells caused a significant down-regulation of FABP1 mRNA expression. FOXA1 activated the FABP1 promoter through binding to a cluster of elements between -229 and -592bp, whereas PPARα operated through a conserved proximal element at -59bp. Finally, FABP1, FOXA1 and PPARα were concomitantly repressed in animal models of NAFLD and in human nonalcoholic fatty livers, whereas C/EBPα was induced or did not change. We conclude that human FABP1 has a complex mechanism of regulation where C/EBPα displaces HNF4α and hampers activation by FOXA1 and PPARα. Alteration of expression of these transcription factors in NAFLD leads to FABP1 gen repression and could exacerbate lipotoxicity and disease progression.
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Affiliation(s)
- Carla Guzmán
- Experimental Hepatology Unit, IIS Hospital La Fe, Valencia, Spain
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12
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Tolosa L, Donato MT, Pérez-Cataldo G, Castell JV, Gómez-Lechón MJ. Upgrading cytochrome P450 activity in HepG2 cells co-transfected with adenoviral vectors for drug hepatotoxicity assessment. Toxicol In Vitro 2012; 26:1272-7. [DOI: 10.1016/j.tiv.2011.11.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 09/08/2011] [Accepted: 11/09/2011] [Indexed: 11/25/2022]
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13
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Sattler S, Reiche D, Sturtzel C, Karas I, Richter S, Kalb ML, Gregor W, Hofer E. The human C-type lectin-like receptor CLEC-1 is upregulated by TGF-β and primarily localized in the endoplasmic membrane compartment. Scand J Immunol 2012; 75:282-92. [PMID: 22117783 DOI: 10.1111/j.1365-3083.2011.02665.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The orphan receptor CLEC-1 is part of a subfamily of C-type lectin-like receptors, which is encoded in the human natural killer gene complex and comprises several pattern recognition receptors important for innate immune functions. As information on human CLEC-1 is still very limited, we aimed to further characterize this receptor. Similar to another subfamily member, LOX-1, expression of CLEC-1 mRNA was detected in myeloid cells as well as in endothelial cells. CLEC-1 protein displayed N-linked glycosylation and formed dimers. However, in contrast to other members of the subfamily, expression levels were upregulated by transforming growth factor (TGF)-β, but not significantly affected by proinflammatory stimuli. It is intriguing that human CLEC-1 could only be detected intracellularly with a staining pattern resembling endoplasmic reticulum proteins. Neither TGF-β nor inflammatory stimuli could promote significant translocation to the cell surface. These findings are in accordance with a primarily intracellular localization and function of human CLEC-1.
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Affiliation(s)
- S Sattler
- Department of Vascular Biology and Thrombosis Research Immunology Dermatology, Division of Immunology, Allergy and Infectious Diseases, Medical University of Vienna, Vienna, Austria.
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Tsou TC, Chao HR, Yeh SC, Tsai FY, Lin HJ. Zinc induces chemokine and inflammatory cytokine release from human promonocytes. JOURNAL OF HAZARDOUS MATERIALS 2011; 196:335-341. [PMID: 21974847 DOI: 10.1016/j.jhazmat.2011.09.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 05/31/2023]
Abstract
Our previous studies found that zinc oxide (ZnO) particles induced expression of intercellular adhesion molecule-1 (ICAM-1) protein in vascular endothelial cells via NF-κB and that zinc ions dissolved from ZnO particles might play the major role in the process. This study aimed to determine if zinc ions could cause inflammatory responses in a human promonocytic leukemia cell line HL-CZ. Conditioned media from the zinc-treated HL-CZ cells induced ICAM-1 protein expression in human umbilical vein endothelial cells (HUVEC). Zinc treatment induced chemokine and inflammatory cytokine release from HL-CZ cells. Inhibition of NFκB activity by over-expression of IκBα in HL-CZ cells did not block the conditioned medium-induced ICAM-1 protein expression in HUVEC cells. Zinc treatment induced activation of multiple immune response-related transcription factors in HL-CZ cells. These results clearly show that zinc ions induce chemokine and inflammatory cytokine release from human promonocytes, accompanied with activation of multiple immune response-related transcription factors. Our in vitro evidence in the zinc-induced inflammatory responses of vascular cells provides a critical linkage between zinc exposure and pathogenesis of those inflammatory vascular diseases.
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Affiliation(s)
- Tsui-Chun Tsou
- Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan, Miaoli 350, Taiwan.
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15
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The VEGF-regulated transcription factor HLX controls the expression of guidance cues and negatively regulates sprouting of endothelial cells. Blood 2011; 117:2735-44. [PMID: 21224470 DOI: 10.1182/blood-2010-07-293209] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The HLX gene encoding a diverged homeobox transcription factor has been found to be up-regulated by vascular endothelial growth factor-A (VEGF-A) in endothelial cells. We have now investigated the gene repertoire induced by HLX and its potential biologic function. HLX strongly increased the transcripts for several repulsive cell-guidance proteins including UNC5B, plexin-A1, and semaphorin-3G. In addition, genes for transcriptional repressors such as HES-1 were up-regulated. In line with these findings, adenoviral overexpression of HLX inhibited endothelial cell migration, sprouting, and vessel formation in vitro and in vivo, whereas proliferation was unaffected. This inhibition of sprouting was caused to a significant part by HLX-mediated up-regulation of UNC5B as shown by short hairpin RNA (shRNA)-mediated down-modulation of the respective mRNA. VEGF-A stimulation of endothelial cells induced elevated levels of HLX over longer time periods resulting in especially high up-regulation of UNC5B mRNA as well as an increase in cells displaying UNC5B at their surface. However, induction of HLX was strongly reduced and UNC5B up-regulation completely abrogated when cells were exposed to hypoxic conditions. These data suggest that HLX may function to balance attractive with repulsive vessel guidance by up-regulating UNC5B and to down-modulate sprouting under normoxic conditions.
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17
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Tsou TC, Yeh SC, Tsai FY, Lin HJ, Cheng TJ, Chao HR, Tai LA. Zinc oxide particles induce inflammatory responses in vascular endothelial cells via NF-κB signaling. JOURNAL OF HAZARDOUS MATERIALS 2010; 183:182-8. [PMID: 20674161 DOI: 10.1016/j.jhazmat.2010.07.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 06/03/2010] [Accepted: 07/03/2010] [Indexed: 05/25/2023]
Abstract
This study investigated inflammatory effects of zinc oxide (ZnO) particles on vascular endothelial cells. The effects of 50 and 100-nm ZnO particles on human umbilical vein endothelial cells (HUVECs) were characterized by assaying cytotoxicity, cell proliferation, and glutathione levels. A marked drop in survival rate was observed when ZnO concentration was increased to 45 μg/ml. ZnO concentrations of ≤3 μg/ml resulted in increased cell proliferation, while those of ≤45 μg/ml caused dose-dependent increases in oxidized glutathione levels. Treatments with ZnO concentrations ≤45 μg/ml were performed to determine the expression of intercellular adhesion molecule-1 (ICAM-1) protein, an indicator of vascular endothelium inflammation, revealing that ZnO particles induced a dose-dependent increase in ICAM-1 expression and marked increases in NF-κB reporter activity. Overexpression of IκBα completely inhibited ZnO-induced ICAM-1 expression, suggesting NF-κB plays a pivotal role in regulation of ZnO-induced inflammation in HUVECs. Additionally, TNF-α, a typical inflammatory cytokine, induced ICAM-1 expression in an NF-κB-dependent manner, and ZnO synergistically enhanced TNF-α-induced ICAM-1 expression. Both 50 and 100-nm ZnO particles agglomerated to similar size distributions. This study reveals an important role for ZnO in modulating inflammatory responses of vascular endothelial cells via NF-κB signaling, which could have important implications for treatments of vascular disease.
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Affiliation(s)
- Tsui-Chun Tsou
- Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan.
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18
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Bell JA, Reed MA, Consitt LA, Martin OJ, Haynie KR, Hulver MW, Muoio DM, Dohm GL. Lipid partitioning, incomplete fatty acid oxidation, and insulin signal transduction in primary human muscle cells: effects of severe obesity, fatty acid incubation, and fatty acid translocase/CD36 overexpression. J Clin Endocrinol Metab 2010; 95:3400-10. [PMID: 20427507 PMCID: PMC2928911 DOI: 10.1210/jc.2009-1596] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Intracellular lipid partitioning toward storage and the incomplete oxidation of fatty acids (FA) have been linked to insulin resistance. OBJECTIVE To gain insight into how intracellular lipid metabolism is related to insulin signal transduction, we examined the effects of severe obesity, excess FA, and overexpression of the FA transporter, FA translocase (FAT)/CD36, in primary human skeletal myocytes. DESIGN, SETTING, AND PATIENTS Insulin signal transduction, FA oxidation, and metabolism were measured in skeletal muscle cells harvested from lean and severely obese women. To emulate the obesity phenotype in our cell culture system, we incubated cells from lean individuals with excess FA or overexpressed FAT/CD36 using recombinant adenoviral technology. RESULTS Complete oxidation of FA was significantly reduced, whereas total lipid accumulation, FA esterification into lipid intermediates, and incomplete oxidation were up-regulated in the muscle cells of severely obese subjects. Insulin signal transduction was reduced in the muscle cells from severely obese subjects compared to lean controls. Incubation of muscle cells from lean subjects with lipids reduced insulin signal transduction and increased lipid storage and incomplete FA oxidation. CD36 overexpression increased FA transport capacity, but did not impair complete FA oxidation and insulin signal transduction in muscle cells from lean subjects. CONCLUSIONS Cultured myocytes from severely obese women express perturbations in FA metabolism and insulin signaling reminiscent of those observed in vivo. The obesity phenotype can be recapitulated in muscle cells from lean subjects via exposure to excess lipid, but not by overexpressing the FAT/CD36 FA transporter.
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Affiliation(s)
- Jill A Bell
- East Carolina University, Brody Medical School, Department of Physiology, 600 Moye Boulevard, Greenville, NC 27834, USA
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19
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Donato MT, Hallifax D, Picazo L, Castell JV, Houston JB, Gomez-Lechón MJ, Lahoz A. Metabolite formation kinetics and intrinsic clearance of phenacetin, tolbutamide, alprazolam, and midazolam in adenoviral cytochrome P450-transfected HepG2 cells and comparison with hepatocytes and in vivo. Drug Metab Dispos 2010; 38:1449-55. [PMID: 20501911 DOI: 10.1124/dmd.110.033605] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cryopreserved human hepatocytes and other in vitro systems often underpredict in vivo intrinsic clearance (CL(int)). The aim of this study was to explore the potential utility of HepG2 cells transduced with adenovirus vectors expressing a single cytochrome P450 enzyme (Ad-CYP1A2, Ad-CYP2C9, or Ad-CYP3A4) for metabolic clearance predictions. The kinetics of metabolite formation from phenacetin, tolbutamide, and alprazolam and midazolam, selected as substrates probes for CYP1A2, CYP2C9, and CYP3A4, respectively, were characterized in this in vitro system. The magnitude of the K(m) or S(50) values observed in Ad-P450 cells was similar to those found in the literature for other human liver-derived systems. For each substrate, CL(int) (or CL(max)), values from Ad-P450 systems were scaled to human hepatocytes in primary culture using the relative activity factor (RAF) approach. Scaled Ad-P450 CL(int) values were approximately 3- to 6-fold higher (for phenacetin O-deethylation, tolbutamide 4-hydroxylation, and alprazolam 4-hydroxyaltion) or lower (midazolam 1'-hydroxylation) than those reported for human cryopreserved hepatocytes in suspension. Comparison with the in vivo data reveals that Ad-P450 cells provide a favorable prediction of CL(int) for the substrates studied (in a range of 20-200% in vivo observed CL(int)). This is an improvement compared with the consistent underpredictions (<10-50% in in vivo observed CL(int)) found in cryopreserved hepatocyte studies with the same substrates. These results suggest that the Ad-P450 cell is a promising in vitro system for clearance predictions of P450-metabolized drugs.
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Affiliation(s)
- M Teresa Donato
- Unidad de Hepatología Experimental, Centro de Investigación, Hospital La Fe, Avenida Campanar 21, Valencia, Spain.
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20
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Marfil V, Moya M, Pierreux CE, Castell JV, Lemaigre FP, Real FX, Bort R. Interaction between Hhex and SOX13 modulates Wnt/TCF activity. J Biol Chem 2009; 285:5726-37. [PMID: 20028982 DOI: 10.1074/jbc.m109.046649] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fine-tuning of the Wnt/TCF pathway is crucial for multiple embryological processes, including liver development. Here we describe how the interaction between Hhex (hematopoietically expressed homeobox) and SOX13 (SRY-related high mobility group box transcription factor 13), modulates Wnt/TCF pathway activity. Hhex is a homeodomain factor expressed in multiple endoderm-derived tissues, like the liver, where it is essential for proper development. The pleiotropic expression of Hhex during embryonic development and its dual role as a transcriptional repressor and activator suggest the presence of different tissue-specific partners capable of modulating its activity and function. While searching for developmentally regulated Hhex partners, we set up a yeast two-hybrid screening using an E9.5-10.5 mouse embryo library and the N-terminal domain of Hhex as bait. Among the putative protein interactors, we selected SOX13 for further characterization. We found that SOX13 interacts directly with full-length Hhex, and we delineated the interaction domains within the two proteins. SOX13 is known to repress Wnt/TCF signaling by interacting with TCF1. We show that Hhex is able to block the SOX13-dependent repression of Wnt/TCF activity by displacing SOX13 from the SOX13 x TCF1 complex. Moreover, Hhex de-repressed the Wnt/TCF pathway in the ventral foregut endoderm of cultured mouse embryos electroporated with a SOX13-expressing plasmid. We conclude that the interaction between Hhex and SOX13 may contribute to control Wnt/TCF signaling in the early embryo.
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Affiliation(s)
- Vanessa Marfil
- Unitat de Biologia Cellular i Molecular, Institut Municipal d'Investigació Mèdica, Universitat Pompeu Fabra, Barcelona 08003, Spain
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21
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Cortínez G, Sapag A, Israel Y. RNA interference against aldehyde dehydrogenase-2: development of tools for alcohol research. Alcohol 2009; 43:97-104. [PMID: 19251111 DOI: 10.1016/j.alcohol.2008.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 10/27/2008] [Accepted: 12/09/2008] [Indexed: 12/20/2022]
Abstract
Liver alcohol dehydrogenase oxidizes ethanol to acetaldehyde, which is further oxidized to acetate by aldehyde dehydrogenase-2 (ALDH2*1). Individuals who carry a low-activity ALDH2 (ALDH2*2) display high blood acetaldehyde levels after ethanol consumption, which leads to dysphoric effects, such as facial flushing, nausea, dizziness, and headache ("Asian alcohol phenotype"), which result in an aversion to alcohol and protection against alcohol abuse and alcoholism. Mimicking this phenotype may reduce alcohol consumption in alcoholics. RNA interference (RNAi) is a cell process in which a short interfering RNA (siRNA) of 21-25 bp guides the degradation of a complementary target mRNA. Thus, siRNAs may be useful in mimicking the Asian phenotype by inhibiting ALDH2 gene expression. We determined the inhibitory effect of three chemically synthesized siRNAs targeted against rat ALDH2 mRNA in human embryonic kidney cells (HEK-293 cell lines) transfected with a plasmid carrying the rat ALDH2 cDNA. Two of the three siRNAs were active, yielding a 65-75% reduction of ALDH2 activity. Based on the most promising siRNA sequence, three short hairpin RNA (shRNA) genes driven by the human U6 RNA promoter were designed and cloned in a plasmid. After transfection of HEK-293 cells, one of the genes was shown to be active, yielding a 50% reduction of ALDH2 activity. This effect is consistent with a 50% reduction in ALDH2 mRNA, whereas neither beta-actin mRNA nor the interferon-inducible transmembrane protein-1 mRNA levels were affected. This study describes chemically synthesized siRNAs and an endogenously synthesized shRNA, which reduce ALDH2 activity and constitute tools that should be of value for further alcohol research.
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Renckens R, Roelofs JJTH, Stegenga ME, Florquin S, Levi M, Carmeliet P, Van't Veer C, van der Poll T. Transgenic tissue-type plasminogen activator expression improves host defense during Klebsiella pneumonia. J Thromb Haemost 2008; 6:660-8. [PMID: 18194423 DOI: 10.1111/j.1538-7836.2008.02892.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Severe pneumonia is associated with a local inhibition of fibrinolysis in the lung as reflected by strongly reduced pulmonary plasminogen activator activity. OBJECTIVES To study the effect of elevation of local plasminogen activator activity during pneumonia caused by the common respiratory pathogen Klebsiella pneumoniae. METHODS Female C57Bl/6 mice were inoculated intranasally with a replication-defective adenoviral vector expressing human tissue-type plasminogen activator or a control vector 24 h before intranasal infection with K. pneumoniae. RESULTS Mice infected with Klebsiella via the airways developed overt pneumonia, which was accompanied by a downregulation of pulmonary tissue-type plasminogen activator levels at protein and mRNA levels. Pulmonary overexpression of human tissue-type plasminogen activator resulted in increased fibrinolytic activity in the lungs during pneumonia, as indicated by higher D-dimer levels and reduced fibrin deposition. Interestingly, overexpression of tissue-type plasminogen activator markedly improved host defense against pneumonia: mice treated with the tissue-type plasminogen activator vector displayed less bacterial growth and dissemination, attenuated distant organ injury and a reduced mortality. CONCLUSIONS These data demonstrate that local elevation of plasminogen activator activity in the lungs improves host defense against severe gram-negative pneumonia and sepsis.
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Affiliation(s)
- R Renckens
- Center for Infection and Immunity Amsterdam (CINIMA), and Center for Experimental and Molecular Medicine, University of Amsterdam, Amsterdam, The Netherlands.
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23
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Jhaveri R, McHutchison J, Patel K, Qiang G, Diehl AM. Specific polymorphisms in hepatitis C virus genotype 3 core protein associated with intracellular lipid accumulation. J Infect Dis 2008; 197:283-91. [PMID: 18177246 DOI: 10.1086/524846] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Steatosis is a common histological finding and a poor prognostic indicator in patients with hepatitis C virus (HCV) infection. In HCV genotype 3-infected patients, the etiology of steatosis appears to be closely correlated with unknown viral factors that increase intracellular lipid levels. We hypothesize that specific sequence polymorphisms in HCV genotype 3 core protein may be associated with hepatic intracellular lipid accumulation. METHODS Using selected serum samples from 8 HCV genotype 3-infected patients with or without steatosis, we sequenced the HCV core gene to identify candidate polymorphisms associated with increased intracellular lipid levels. RESULTS Two polymorphisms at positions 182 and 186 of the core protein correlated with the presence (P= .03) and absence (P= .005) of intrahepatic steatosis. Transfected liver cell lines expressing core protein with steatosis-associated polymorphisms had increased intracellular lipid levels compared with non-steatosis-associated core isolates, as measured by oil red O staining (P= .02). Site-specific mutagenesis performed at positions 182 and 186 in steatosis-associated core genes yielded proteins that had decreased intracellular lipid levels in transfected cells (P= .03). CONCLUSIONS We have identified polymorphisms in HCV core protein genotype 3 that produce increased intracellular lipid levels and thus may play a significant role in lipid metabolism or trafficking, contributing to steatosis.
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Affiliation(s)
- Ravi Jhaveri
- Division of Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710, USA.
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24
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Sarkar SA, Gunter J, Bouchard R, Reusch JEB, Wiseman A, Gill RG, Hutton JC, Pugazhenthi S. Dominant negative mutant forms of the cAMP response element binding protein induce apoptosis and decrease the anti-apoptotic action of growth factors in human islets. Diabetologia 2007; 50:1649-59. [PMID: 17593347 DOI: 10.1007/s00125-007-0707-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Accepted: 04/03/2007] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS Transplantation of islets is a viable option for the treatment of diabetes. A significant proportion of islets is lost during isolation, storage and after transplantation as a result of apoptosis. cAMP response element binding protein (CREB) is an important cell survival factor. The aim of the present study was to determine whether preservation of CREB function is needed for survival of human islets. MATERIALS AND METHODS To determine the effects of downregulation of CREB activity on beta cell apoptosis in a transplantation setting, adenoviral vectors were used to express two dominant negative mutant forms of CREB in human islets isolated from cadaveric donors. Markers of apoptosis were determined in these transduced islets under basal conditions and following treatment with growth factor. RESULTS Expression of CREB mutants in human islets resulted in significant (p < 0.001) activation of caspase-9, a key regulatory enzyme in the mitochondrial pathway of apoptosis, when compared with islets transduced with adenoviral beta galactosidase. Immunocytochemical analysis showed the activation of caspase-9 to be predominantly in beta cells. Other definitive markers of apoptosis such as parallel activation of caspase-3, accumulation of cleaved poly-(ADP-ribose) polymerase and nuclear condensation were also observed. Furthermore, the anti-apoptotic action of growth factors exendin-4 and betacellulin in human islets exposed to cytokines was partially lost when CREB function was impaired. CONCLUSIONS/INTERPRETATION Our findings suggest that impairment of CREB-mediated transcription could lead to loss of islets by apoptosis with potential implications in islet transplantation as well as in the mechanism of beta cell loss leading to diabetes.
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Affiliation(s)
- S A Sarkar
- Barbara Davis Center for Childhood Diabetes and Rocky Mountain Islet Transplantation Program, Aurora, CO, USA
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25
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Montori-Grau M, Guitart M, Lerin C, Andreu A, Newgard C, García-Martínez C, Gómez-Foix A. Expression and glycogenic effect of glycogen-targeting protein phosphatase 1 regulatory subunit GL in cultured human muscle. Biochem J 2007; 405:107-13. [PMID: 17555403 PMCID: PMC1925244 DOI: 10.1042/bj20061572] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Glycogen-targeting PP1 (protein phosphatase 1) subunit G(L) (coded for by the PPP1R3B gene) is expressed in human, but not rodent, skeletal muscle. Its effects on muscle glycogen metabolism are unknown. We show that G(L) mRNA levels in primary cultured human myotubes are similar to those in freshly excised muscle, unlike subunits G(M) (gene PPP1R3A) or PTG (protein targeting to glycogen; gene PPP1R3C), which decrease strikingly. In cultured myotubes, expression of the genes coding for G(L), G(M) and PTG is not regulated by glucose or insulin. Overexpression of G(L) activates myotube GS (glycogen synthase), glycogenesis in glucose-replete and -depleted cells and glycogen accumulation. Compared with overexpressed G(M), G(L) has a more potent activating effect on glycogenesis, while marked enhancement of their combined action is only observed in glucose-replete cells. G(L) does not affect GP (glycogen phosphorylase) activity, while co-overexpression with muscle GP impairs G(L) activation of GS in glucose-replete cells. G(L) enhances long-term glycogenesis additively to glucose depletion and insulin, although G(L) does not change the phosphorylation of GSK3 (GS kinase 3) on Ser9 or its upstream regulator kinase Akt/protein kinase B on Ser473, nor its response to insulin. In conclusion, in cultured human myotubes, the G(L) gene is expressed as in muscle tissue and is unresponsive to glucose or insulin, as are G(M) and PTG genes. G(L) activates GS regardless of glucose, does not regulate GP and stimulates glycogenesis in combination with insulin and glucose depletion.
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Affiliation(s)
- Marta Montori-Grau
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Maria Guitart
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Carles Lerin
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Antonio L. Andreu
- †Centre d’Investigació en Bioquímica i Biologia Molecular (A.L.A.), University Hospital Vall d'Hebron, 08035-Barcelona, Spain
| | - Christopher B. Newgard
- ‡Sarah W. Stedman Nutrition and Metabolism Center and Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27704, U.S.A
| | - Cèlia García-Martínez
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
| | - Anna M. Gómez-Foix
- *Departament de Bioquímica i Biologia Molecular, Facultat de Biología, Universitat de Barcelona, 08028-Barcelona, Spain
- To whom correspondence should be addressed (email )
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Wendeler MW, Drenckhahn D, Gessner R, Baumgartner W. Intestinal LI-cadherin acts as a Ca2+-dependent adhesion switch. J Mol Biol 2007; 370:220-30. [PMID: 17512947 DOI: 10.1016/j.jmb.2007.04.062] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 04/13/2007] [Accepted: 04/19/2007] [Indexed: 12/20/2022]
Abstract
Cadherins are Ca(2+)-dependent transmembrane glycoproteins that mediate cell-cell adhesion and are important for the structural integrity of epithelia. LI-cadherin and the classical E-cadherin are the predominant two cadherins in the intestinal epithelium. LI-cadherin consists of seven extracellular cadherin repeats and a short cytoplasmic part that does not interact with catenins. In contrast, E-cadherin is composed of five cadherin repeats and a large cytoplasmic domain that is linked via catenins to the actin cytoskeleton. Whereas E-cadherin is concentrated in adherens junctions, LI-cadherin is evenly distributed along the lateral contact area of intestinal epithelial cells. To investigate if the particular structural properties of LI-cadherin result in a divergent homotypic adhesion mechanism, we analyzed the binding parameters of LI-cadherin on the single molecule and the cellular level using atomic force microscopy, affinity chromatography and laser tweezer experiments. Homotypic trans-interaction of LI-cadherin exhibits low affinity binding with a short lifetime of only 1.4 s. Interestingly, LI-cadherin binding responds to small changes in extracellular Ca(2+) below the physiological plasma concentration with a high degree of cooperativity. Thus, LI-cadherin might serve as a Ca(2+)-regulated switch for the adhesive system on basolateral membranes of the intestinal epithelium.
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Affiliation(s)
- Markus W Wendeler
- Biomedical Research Center, Virchow Hospital of Charité Medical School Berlin, D-13353 Berlin, Germany
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27
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Quesada E, Castell JV, Vilanova E, Carrera V. Over-expression of neuropathy target esterase activity in bovine chromaffin cell cultures by adenovirus-mediated gene transfer. Toxicol Lett 2007; 168:286-91. [PMID: 17184936 DOI: 10.1016/j.toxlet.2006.10.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 10/16/2006] [Indexed: 11/23/2022]
Abstract
Chromaffin cells in culture show high neuropathy target esterase (NTE) activity. It is well known that inhibition and specific modification of NTE by some organophosphorus (OPs) compounds induces a neurodegenerative neuropathy. It has been suggested that NTE is responsible for phosphatidylcholine homeostasis, although its role in neuropathy induction remains unclear. The cDNA of human NTE (4.4kbp) was inserted into an adenoviral vector. Bovine chromaffin cells cultured at 50,000 cells/well were incubated with the vector for 2h and after removing the volume of infection, cells were maintained in the incubator. After 24h, NTE activity was 6.8+/-0.5mU/10(6) cells in untreated cells and 14.8+/-1.5mU/10(6) cells, 19.3+/-2.9mU/10(6) cells, 24.8+/-0.9mU/10(6) cells and 30.9+/-1.0mU/10(6) cells in cells incubated with 2, 4, 8 and 16microl of vector, respectively. After 60min of inhibition with mipafox increased concentrations, the calculated I(50) (60min) values were 5.5, 6.2 and 6.6microM for cells infected with 0, 2 and 10microl of vector preparation. We confirm that the adenoviral vector containing the human NTE gene is active in bovine chromaffin cells in culture and that the NTE activity expressed by the vector shows the same inhibition pattern by the neuropathic OP mipafox as the NTE activity of bovine chromaffin cells and cells remained viable after the high NTE activity expression.
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Affiliation(s)
- Encarna Quesada
- Unidad de Toxicología y Seguridad Química, Instituto de Bioingeniería, Universidad Miguel Hernández. Avda. de la Universidad, s/n. E-03202 Elche (Alicante), Spain.
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Plageman TF, Yutzey KE. Microarray analysis of Tbx5-induced genes expressed in the developing heart. Dev Dyn 2007; 235:2868-80. [PMID: 16894625 DOI: 10.1002/dvdy.20923] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Tbx5 is a member of the T-box family of transcription factors and is associated with Holt-Oram syndrome (HOS), a congenital disorder characterized by heart and limb defects. Although implicated in several processes during development, only a few genes regulated by Tbx5 have been reported. To identify candidate genes regulated by Tbx5 during heart development, a microarray approach was used. A cardiac-derived mouse cell line (1H) was infected with adenoviruses expressing Tbx5 or beta-galactosidase and RNA was isolated for analysis using an Affymetrix gene chip representing over 39,000 transcripts. Real-time reverse transcriptase-polymerase chain reaction confirmed Tbx5 induction of a subset of the genes, including nppa, photoreceptor cadherin, brain creatine kinase, hairy/enhancer-of-split related 2, and gelsolin. In situ hybridization analysis indicated overlapping expression of these genes with tbx5 in the embryonic mouse heart. In addition, the effect of HOS-associated mutations on the ability of Tbx5 to induce target gene expression was evaluated. Together, these data identify several genes induced by Tbx5 that are potentially important during cardiac development. These genes represent new candidate gene targets of Tbx5 that may be related to congenital heart malformations associated with HOS.
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Affiliation(s)
- Timothy F Plageman
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, ML7020, Cincinnati, Ohio, USA
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29
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Ito T, Fujio Y, Takahashi K, Azuma J. Degradation of NFAT5, a transcriptional regulator of osmotic stress-related genes, is a critical event for doxorubicin-induced cytotoxicity in cardiac myocytes. J Biol Chem 2006; 282:1152-60. [PMID: 17105721 DOI: 10.1074/jbc.m609547200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Nuclear factor-activated T cell 5 (NFAT5), a novel member of the NFAT family of proteins, was originally identified as a transcriptional factor responsible for adaptation to hyperosmotic stress. Though NFAT5 is ubiquitously expressed, the biological functions of NFAT5 remain to be clarified, especially in the tissues that are not exposed to hypertonicity, including hearts. In the present study, we focused on the cardioprotective roles of NFAT5 against the cardiotoxic anti-tumor agent doxorubicin (Dox). In cultured cardiomyocytes, transcripts of the hypertonicity-inducible genes, such as taurine transporter (TauT) and sodium/myo-inositol transporter, were down-regulated by Dox. Interestingly, NFAT5 protein, but not mRNA, was decreased in cardiomyocytes exposed to Dox. Treatment of proteasome inhibitors, MG-132 or proteasome-specific inhibitor 1, prevented the Dox-mediated decrease of NFAT5 protein. Further, ubiquitin-conjugated NFAT5 was not detected in cultured cardiomyocytes treated with MG-132 and/or Dox, as assessed by immunoprecipitation assay, suggesting Dox-induced degradation through ubiquitin-independent proteasome pathway. Importantly, inhibition of NFAT5 with overexpression of dominant-negative NFAT5 decreased cell viability and increased creatine kinase leakage into culture medium. Consistently, small interfering RNA targeting NFAT5 gene enhanced myocyte death. These findings suggest that Dox promoted the degradation of NFAT5 protein, reducing cell viability in cardiomyocytes. This is the first demonstration that NFAT5 is a positive regulator of cardiomyocyte survival.
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Affiliation(s)
- Takashi Ito
- Department of Clinical Pharmacology and Pharmacogenomics, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan
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30
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Zschenker O, Illies T, Ameis D. Overexpression of lysosomal acid lipase and other proteins in atherosclerosis. J Biochem 2006; 140:23-38. [PMID: 16877765 DOI: 10.1093/jb/mvj137] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Atherosclerosis is one of the major causes of morbidity and mortality in the western world. The existing data of elevated expression levels of proteins like DNA damage and DNA repair enzymes in human atherosclerotic plaques are reviewed. From the literature, the effect of overexpression of different proteins using adenoviral vectors or the model of transgenic mice on the development of atherosclerosis will be discussed. Special focus is placed on the lysosomal acid lipase (LAL), because LAL connects extra-cellular with intra-cellular lipid metabolism and is the only hydrolase for cleavage of cholesteryl esters delivered to the lysosomes. Patients with a deficiency of LAL show an accumulation of lipids in the cells and develop pre-mature atherosclerosis. To answer the question of the influence of LAL in atherosclerosis if overexpressed, we show for the first time data of transgenic mice overexpressing LAL and the effect on the lipid level.
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Affiliation(s)
- Oliver Zschenker
- Medical Center, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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31
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Renckens R, Roelofs JJTH, Bonta PI, Florquin S, de Vries CJM, Levi M, Carmeliet P, van't Veer C, van der Poll T. Plasminogen activator inhibitor type 1 is protective during severe Gram-negative pneumonia. Blood 2006; 109:1593-601. [PMID: 17032919 DOI: 10.1182/blood-2006-05-025197] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Plasminogen activator inhibitor type-1 (PAI-1) levels are consistently elevated in patients with severe pneumonia and sepsis and highly predictive for an unfavorable outcome. In addition, pneumonia is associated with strongly elevated PAI-1 levels in the pulmonary compartment. However, whether PAI-1 causally affects antibacterial host defense in vivo remains unknown. We report here that pneumonia caused by the common respiratory pathogen Klebsiella pneumoniae is associated with local production of PAI-1 in the lungs of wild-type mice. PAI-1 deficiency impaired host defense as reflected by enhanced lethality and increased bacterial growth and dissemination in mice with a targeted deletion of the PAI-1 gene. Conversely, transgenic overexpression of PAI-1 in the lung using a replication-defective adenoviral vector markedly improved host defense against Klebsiella pneumonia and sepsis. PAI-1 deficiency reduced accumulation of neutrophils in the lungs during pneumonia, whereas PAI-1 overexpression in healthy lungs resulted in neutrophil influx, suggesting that PAI-1 protects the host against Klebsiella pneumonia by promoting neutrophil recruitment to the pulmonary compartment. These data demonstrate for the first time that PAI-1 is essential for host defense against severe Gram-negative pneumonia.
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Affiliation(s)
- Rosemarijn Renckens
- Center for Infection and Immunity Amsterdam, Department of Pathology, University of Amsterdam, The Netherlands.
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32
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Shelton EL, Yutzey KE. Tbx20 regulation of endocardial cushion cell proliferation and extracellular matrix gene expression. Dev Biol 2006; 302:376-88. [PMID: 17064679 PMCID: PMC1847324 DOI: 10.1016/j.ydbio.2006.09.047] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 09/26/2006] [Accepted: 09/27/2006] [Indexed: 10/24/2022]
Abstract
While recent work has implicated Tbx20 in myocardial maturation and proliferation, the role of Tbx20 in heart valve development remains relatively unknown. Tbx20 expression was manipulated in primary avian endocardial cells in order to elucidate its function in developing endocardial cushions. Tbx20 gain of function was achieved with a Tbx20-adenovirus, and endogenous Tbx20 expression was inhibited with Tbx20-specific siRNA in cultured endocardial cushion cells. With Tbx20 gain of function, the expression of chondroitin sulfate proteoglycans (CSPG), including aggrecan and versican, was decreased, while the expression of the matrix metalloproteinases (MMP) mmp9 and mmp13 was increased. Consistent results were observed with Tbx20 loss of function, where the expression of CSPG genes increased and MMP genes decreased. In addition, cushion mesenchyme proliferation increased with infection of a Tbx20-adenovirus and decreased with transfection of Tbx20-specfic siRNA. Furthermore, BMP2 treatment resulted in increased Tbx20 expression in endocardial cushion cells, and loss of Tbx20 led to increased Tbx2 and decreased N-myc gene expression. Taken together, these data support a role for Tbx20 in repressing extracellular matrix remodeling and promoting cell proliferation in mesenchymal valve precursor populations in endocardial cushions during embryonic development.
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33
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Renckens R, Roelofs JJTH, Florquin S, de Vos AF, Pater JM, Lijnen HR, Carmeliet P, van 't Veer C, van der Poll T. Endogenous tissue-type plasminogen activator is protective during Escherichia coli-induced abdominal sepsis in mice. THE JOURNAL OF IMMUNOLOGY 2006; 177:1189-96. [PMID: 16818777 DOI: 10.4049/jimmunol.177.2.1189] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Sepsis is associated with enhanced production of tissue-type plasminogen activator (tPA). We investigated the function of endogenous tPA in the immune responses to Escherichia coli-induced abdominal sepsis using tPA gene-deficient (tPA(-/-)) and normal wild-type (WT) mice. tPA(-/-) mice demonstrated an impaired defense against E. coli peritonitis as indicated by higher bacterial loads at the primary site of the infection, enhanced dissemination, and reduced survival. The protective function of tPA was independent of plasmin since plasminogen gene-deficient (Plg(-/-)) mice were indistinguishable from WT mice. Relative to WT mice, tPA(-/-) mice demonstrated similar neutrophil counts in the peritoneal cavity despite much higher bacterial loads and higher local concentrations of neutrophil attracting chemokines, suggesting a reduced migratory response. In line, tPA(-/-) mice demonstrated a reduced thioglycolate-induced neutrophil influx into the peritoneal cavity and i.p. injection of WT mice with a replication-defective adenoviral vector expressing tPA caused an enhanced cell migration to the peritoneal cavity during E. coli peritonitis. These findings identify a novel protective function of tPA in abdominal sepsis caused by E. coli that seems independent of its role in the generation of plasmin.
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Affiliation(s)
- Rosemarijn Renckens
- Center of Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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34
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Arden C, Green AR, Hampson LJ, Aiston S, Härndahl L, Greenberg CC, Brady MJ, Freeman S, Poucher SM, Agius L. Increased sensitivity of glycogen synthesis to phosphorylase-a and impaired expression of the glycogen-targeting protein R6 in hepatocytes from insulin-resistant Zucker fa/fa rats. FEBS J 2006; 273:1989-99. [PMID: 16640562 DOI: 10.1111/j.1742-4658.2006.05215.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Hepatic insulin resistance in the leptin-receptor defective Zucker fa/fa rat is associated with impaired glycogen synthesis and increased activity of phosphorylase-a. We investigated the coupling between phosphorylase-a and glycogen synthesis in hepatocytes from fa/fa rats by modulating the concentration of phosphorylase-a. Treatment of hepatocytes from fa/fa rats and Fa/? controls with a selective phosphorylase inhibitor caused depletion of phosphorylase-a, activation of glycogen synthase and stimulation of glycogen synthesis. The flux-control coefficient of phosphorylase on glycogen synthesis was glucose dependent and at 10 mm glucose was higher in fa/fa than Fa/? hepatocytes. There was an inverse correlation between the activities of glycogen synthase and phosphorylase-a in both fa/fa and Fa/? hepatocytes. However, fa/fa hepatocytes had a higher activity of phosphorylase-a, for a corresponding activity of glycogen synthase. This defect was, in part, normalized by expression of the glycogen-targeting protein, PTG. Hepatocytes from fa/fa rats had normal expression of the glycogen-targeting proteins G(L) and PTG but markedly reduced expression of R6. Expression of R6 protein was increased in hepatocytes from Wistar rats after incubation with leptin and insulin. Diminished hepatic R6 expression in the leptin-receptor defective fa/fa rat may be a contributing factor to the elevated phosphorylase activity and/or its high control strength on glycogen synthesis.
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MESH Headings
- Animals
- Carrier Proteins/antagonists & inhibitors
- Carrier Proteins/biosynthesis
- Carrier Proteins/physiology
- Cells, Cultured
- Diabetes Mellitus, Type 2/enzymology
- Diabetes Mellitus, Type 2/genetics
- Disease Models, Animal
- Female
- Glycogen/biosynthesis
- Glycogen/metabolism
- Glycogen/physiology
- Hepatocytes/enzymology
- Insulin/chemistry
- Insulin Resistance/genetics
- Intracellular Signaling Peptides and Proteins
- Leptin/chemistry
- Male
- Obesity/enzymology
- Obesity/genetics
- Phosphoprotein Phosphatases/antagonists & inhibitors
- Phosphoprotein Phosphatases/biosynthesis
- Phosphoprotein Phosphatases/metabolism
- Phosphorylase a/chemistry
- Phosphorylase a/physiology
- Protein Subunits/antagonists & inhibitors
- Protein Subunits/biosynthesis
- Protein Subunits/metabolism
- Rats
- Rats, Wistar
- Rats, Zucker
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Receptors, Leptin
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Affiliation(s)
- Catherine Arden
- School of Clinical Medical Sciences--Diabetes, University of Newcastle upon Tyne, UK
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35
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Ugleholdt R, Poulsen MLH, Holst PJ, Irminger JC, Orskov C, Pedersen J, Rosenkilde MM, Zhu X, Steiner DF, Holst JJ. Prohormone convertase 1/3 is essential for processing of the glucose-dependent insulinotropic polypeptide precursor. J Biol Chem 2006; 281:11050-7. [PMID: 16476726 DOI: 10.1074/jbc.m601203200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The physiology of the incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and their role in type 2 diabetes currently attract great interest. Recently we reported an essential role for prohormone convertase (PC) 1/3 in the cleavage of intestinal proglucagon, resulting in formation of GLP-1, as demonstrated in PC1/3-deficient mice. However, little is known about the endoproteolytic processing of the GIP precursor. This study investigates the processing of proGIP in PC1/3 and PC2 null mice and in cell lines using adenovirus-mediated overexpression. Supporting a role for PC1/3 in proGIP processing, we found co-localization of GIP and PC1/3 but not PC2 in intestinal sections by immunohistochemistry, and analysis of intestinal extracts from PC1/3-deficient animals demonstrated severely impaired processing to GIP, whereas processing to GIP was unaltered in PC2-deficient mice. Accordingly, overexpression of preproGIP in the neuroendocrine AtT-20 cell line that expresses high levels of endogenous PC1/3 and negligible levels of PC2 resulted in production of GIP. Similar results were obtained after co-expression of preproGIP and PC1/3 in GH4 cells that express no PC2 and only low levels of PC1/3. In addition, studies in GH4 cells and the alpha-TC1.9 cell line, expressing PC2 but not PC1/3, indicate that PC2 can mediate processing to GIP but also to other fragments not found in intestinal extracts. Taken together, our data indicate that PC1/3 is essential and sufficient for the production of the intestinal incretin hormone GIP, whereas PC2, although capable of cleaving proGIP, does not participate in intestinal proGIP processing and is not found in intestinal GIP-expressing cells.
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Affiliation(s)
- Randi Ugleholdt
- Department of Medical Physiology, the Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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36
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Karahanian E, Ocaranza P, Israel Y. Aldehyde dehydrogenase (ALDH2) activity in hepatoma cells is reduced by an adenoviral vector coding for an ALDH2 antisense mRNA. Alcohol Clin Exp Res 2006; 29:1384-9. [PMID: 16131845 DOI: 10.1097/01.alc.0000174909.91034.7c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Individuals carrying the Glu487Lys coding mutation in the gene for mitochondrial aldehyde dehydrogenase (ALDH2) have a diminished capacity to metabolize acetaldehyde. This deficiency leads to increases in blood acetaldehyde levels when they consume ethanol, which results in an aversion to alcohol and in marked protection against alcoholism. In the present studies, we aimed to mimic the high-acetaldehyde low-ALDH2 activity phenotype in a rat hepatoma cell line by inhibiting Aldh2 gene expression by an Aldh2 antisense-coding gene carried by an adenoviral vector. METHODS We designed and produced elevated titers of adenoviral vectors (10 virions/ml) carrying Aldh2 cDNA cloned in the reverse orientation preceded by a CMV promoter and followed by a poly-A termination signal. Rat hepatoma cells were infected with these vectors. RESULTS Studies showed that 1) the antisense gene is actively transcribed in the cells and high levels of antisense mRNA are attained, 2) the antisense gene reduced ALDH2 activity by 65%, and 3) when incubated with 10 mM ethanol, acetaldehyde accumulation by cells increased 8-fold to levels (80-90 microM) known to be aversive to animals and humans. CONCLUSIONS Data presented show that antialcohol drugs that inhibit Aldh2 gene expression can be generated endogenously in liver cells infected by an adenoviral vector carrying an antisense-coding gene, thus mimicking the high-acetaldehyde phenotype that exists in humans carrying the Glu487Lys mutation who are protected against alcoholism.
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Affiliation(s)
- Eduardo Karahanian
- Faculty of Health Sciences, Diego Portales University, Faculty of Chemical and Pharmaceutical Sciences, and Millennium Institute for Advanced Studies in Cell Biology and Biotechnology, University of Chile, Santiago, Chile
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37
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Pugazhenthi S, Phansalkar K, Audesirk G, West A, Cabell L. Differential regulation of c-jun and CREB by acrolein and 4-hydroxynonenal. Free Radic Biol Med 2006; 40:21-34. [PMID: 16337876 DOI: 10.1016/j.freeradbiomed.2005.08.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 08/08/2005] [Accepted: 08/08/2005] [Indexed: 12/31/2022]
Abstract
In Alzheimer's disease (AD), oxidative stress-induced lipid peroxidation leads to accumulation of unsaturated aldehydes including acrolein and 4-hydroxynonenal (4HNE) in brain. In this study, we examined the effects of these lipid peroxidation products on apoptotic pathways in cultured neurons. Acrolein and 4HNE increased the levels of active phosphorylated forms of c-jun and CREB, the transcription factors that promote apoptosis and cell survival, respectively. However, they decreased the activity of CREB-dependent BDNF promoter while they increased the activity of promoters responsive to c-jun. We hypothesized that this differential regulation could be due to competition between proapoptotic c-jun and cytoprotective CREB for CBP (CREB-binding protein), a coactivator shared by several transcription factors. In support of this hypothesis, we demonstrate that the decrease of BDNF promoter activity by acrolein and 4HNE could be restored (i) by cotransfection with CBP, (ii) by cotransfection with VP 16-CREB, a constitutively active form of CREB that does not depend on CBP for its activation, or (iii) by inhibiting JNK-mediated c-jun activation. Finally, adenoviral transduction of hippocampal neurons with VP 16-CREB resulted in significant reduction in caspase-3 activation by acrolein and 4HNE. These observations suggest that lipid peroxidation-induced differential regulation of CREB and c-jun might play a role in neurodegeneration in AD.
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Affiliation(s)
- Subbiah Pugazhenthi
- Department of Medicine, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA.
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38
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Croyle MA, Le HT, Linse KD, Cerullo V, Toietta G, Beaudet A, Pastore L. PEGylated helper-dependent adenoviral vectors: highly efficient vectors with an enhanced safety profile. Gene Ther 2005; 12:579-87. [PMID: 15647765 DOI: 10.1038/sj.gt.3302441] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transgene expression from helper-dependent adenoviral (HD-Ad) vectors is effective and long lasting, but not permanent. Their use is also limited by the host response against capsid proteins that precludes successful gene expression upon readministration. In this report, we test the hypothesis that PEGylation of HD-Ad reduces its toxicity and promotes transgene expression upon readministration. PEGylation did not compromise transduction efficiency in vitro and in vivo and reduced peak serum IL-6 levels two-fold. IL-12 and TNF-alpha levels were reduced three- and seven-fold, respectively. Thrombocytopenia was not detected in mice treated with the PEGylated vector. Serum transaminases were not significantly elevated in mice treated with either vector. Mice immunized with 1 x 10(11) particles of unmodified HD-Ad expressing human alpha-1 antitrypsin (hA1AT) were rechallenged 28 days later with 8 x 10(10) particles of unmodified or PEG-conjugated vector expressing beta-galactosidase. Trace levels of beta-galactosidase (52.23+/-19.2 pg/mg protein) were detected in liver homogenates of mice that received two doses of unmodified HD-Ad. Mice rechallenged with PEGylated HD-Ad produced significant levels of beta-galactosidase (5.1+/-0.4 x 10(5) pg/mg protein, P=0.0001). This suggests that PEGylation of HD-Ad vectors may be appropriate for their safe and efficient use in the clinic.
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Affiliation(s)
- M A Croyle
- College of Pharmacy, Division of Pharmaceutics, The University of Texas at Austin, TX 78712, USA
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39
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Schisler JC, Jensen PB, Taylor DG, Becker TC, Knop FK, Takekawa S, German M, Weir GC, Lu D, Mirmira RG, Newgard CB. The Nkx6.1 homeodomain transcription factor suppresses glucagon expression and regulates glucose-stimulated insulin secretion in islet beta cells. Proc Natl Acad Sci U S A 2005; 102:7297-302. [PMID: 15883383 PMCID: PMC1091752 DOI: 10.1073/pnas.0502168102] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have previously described rat insulinoma INS-1-derived cell lines with robust or poor glucose-stimulated insulin secretion (GSIS). In the current study, we have further resolved these lines into three classes: class 1, glucose-unresponsive/glucagon-expressing; class 2, glucose-unresponsive/glucagon-negative; and class 3, glucose-responsive/glucagon-negative. The transcription factor Nkx2.2 was expressed with relative abundance of 3.3, 1.0, and 1.0 in class 1, class 2, and class 3 cells, respectively, whereas Nkx6.1 expression had the opposite trend: 1.0, 2.6, and 6.4 in class 1, class 2, and class 3 cells, respectively. In class 1 cells, overexpressed Nkx6.1 suppressed glucagon expression but did not affect the levels of several other prominent beta cell transcription factors. RNA interference (RNAi)-mediated suppression of Nkx6.1 in class 3 cells resulted in a doubling of glucagon mRNA, with no effect on Pdx1 levels, whereas suppression of Pdx1 in class 3 cells caused a 12-fold increase in glucagon transcript levels, demonstrating independent effects of Nkx6.1 and Pdx1 on glucagon expression in beta cell lines. RNAi-mediated suppression of Nkx6.1 expression in class 3 cells also caused a decrease in GSIS from 13.9- to 3.7-fold, whereas suppression of Pdx1 reduced absolute amounts of insulin secretion without affecting fold response. Finally, RNAi-mediated suppression of Nkx6.1 mRNA in primary rat islets was accompanied by a significant decrease in GSIS relative to control cells. In sum, our studies have revealed roles for Nkx6.1 in suppression of glucagon expression and control of GSIS in islet beta cells.
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Affiliation(s)
- Jonathan C Schisler
- Department of Pharmacology, Sarah W. Stedman Nutrition and Metabolism Center, Durham, NC 27704, USA
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40
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Clarke DL, Belvisi MG, Smith SJ, Hardaker E, Yacoub MH, Meja KK, Newton R, Slater DM, Giembycz MA. Prostanoid receptor expression by human airway smooth muscle cells and regulation of the secretion of granulocyte colony-stimulating factor. Am J Physiol Lung Cell Mol Physiol 2005; 288:L238-50. [PMID: 15640521 DOI: 10.1152/ajplung.00313.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The prostanoid receptors on human airway smooth muscle cells (HASMC) that augment the release by IL-1β of granulocyte colony-stimulating factor (G-CSF) have been characterized and the signaling pathway elucidated. PCR of HASM cDNA identified products corresponding to EP2, EP3, and EP4receptor subtypes. These findings were corroborated at the protein level by immunocytochemistry. IL-1β promoted the elaboration of G-CSF, which was augmented by PGE2. Cicaprost (IP receptor agonist) was approximately equiactive with PGE2, whereas PGD2, PGF2α, and U-46619 (TP receptor agonist) were over 10-fold less potent. Neither SQ 29,548 nor BW A868C (TP and DP1receptor antagonists, respectively) attenuated the enhancement of G-CSF release evoking any of the prostanoids studied. With respect to PGE2, the EP receptor agonists 16,16-dimethyl PGE2(nonselective), misoprostol (EP2/EP3selective), 17-phenyl-ω-trinor PGE2(EP1selective), ONO-AE1-259, and butaprost (both EP2selective) were full agonists at enhancing G-CSF release. AH 6809 (10 μM) and L-161,982 (2 μM), which can be used in HASMC as selective EP2and EP4receptor antagonists, respectively, failed to displace to the right the PGE2concentration-response curve that described the augmented G-CSF release. In contrast, AH 6809 and L-161,982 in combination competitively antagonized PGE2-induced G-CSF release. Augmentation of G-CSF release by PGE2was mimicked by 8-BrcAMP and abolished in cells infected with an adenovirus vector encoding an inhibitor protein of cAMP-dependent protein kinase (PKA). These data demonstrate that PGE2facilitates G-CSF secretion from HASMC through a PKA-dependent mechanism by acting through EP2and EP4prostanoid receptors and that effective antagonism is realized only when both subtypes are blocked concurrently.
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Affiliation(s)
- Deborah L Clarke
- Thoraic Medicine, National Heart and Lung Institute, Imperial College London, London, UK
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41
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Green AR, Aiston S, Greenberg CC, Freeman S, Poucher SM, Brady MJ, Agius L. The Glycogenic Action of Protein Targeting to Glycogen in Hepatocytes Involves Multiple Mechanisms Including Phosphorylase Inactivation and Glycogen Synthase Translocation. J Biol Chem 2004; 279:46474-82. [PMID: 15322104 DOI: 10.1074/jbc.m405660200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of the glycogen-targeting protein PTG promotes glycogen synthase activation and glycogen storage in various cell types. In this study, we tested the contribution of phosphorylase inactivation to the glycogenic action of PTG in hepatocytes by using a selective inhibitor of phosphorylase (CP-91149) that causes dephosphorylation of phosphorylase a and sequential activation of glycogen synthase. Similar to CP-91194, graded expression of PTG caused a concentration-dependent inactivation of phosphorylase and activation of glycogen synthase. The latter was partially counter-acted by the expression of muscle phosphorylase and was not additive with the activation by CP-91149, indicating that it is in part secondary to the inactivation of phosphorylase. PTG expression caused greater stimulation of glycogen synthesis and translocation of glycogen synthase than CP-91149, and the translocation of synthase could not be explained by accumulation of glycogen, supporting an additional role for glycogen synthase translocation in the glycogenic action of PTG. The effects of PTG expression on glycogen synthase and glycogen synthesis were additive with the effects of glucokinase expression, confirming the complementary roles of depletion of phosphorylase a (a negative modulator) and elevated glucose 6-phosphate (a positive modulator) in potentiating the activation of glycogen synthase. PTG expression mimicked the inactivation of phosphorylase caused by high glucose and counteracted the activation caused by glucagon. The latter suggests a possible additional role for PTG on phosphorylase kinase inactivation.
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Affiliation(s)
- Andrew R Green
- Department of Diabetes, School of Clinical Medical Sciences, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom
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42
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Callahan SM, Ming X, Lu SK, Brunner LJ, Croyle MA. Considerations for use of recombinant adenoviral vectors: dose effect on hepatic cytochromes P450. J Pharmacol Exp Ther 2004; 312:492-501. [PMID: 15496614 DOI: 10.1124/jpet.104.075374] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recombinant adenovirus (Ad) serotype 5 is a vector commonly used for gene delivery. Although this vector has a natural tropism for the liver, there is a limited understanding of how Ad administration affects one of the primary hepatic processes, drug metabolism. The effects of systemic administration of a model recombinant adenoviral vector on two hepatic cytochrome P450 (P450) enzymes, CYP3A2 and 2C11, were investigated. Sprague-Dawley rats were treated with one of six vector doses, ranging from 5.7 x 10(6) to 5.7 x 10(12) virus particles (vp)/kg. Hepatic P450 protein expression, catalytic activity, and mRNA levels were measured over 14 days. Ad administration (5.7 x 10(10)-5.7 x 10(12) vp/kg) reduced CYP3A2 over the duration of the study. Six hours after administration of 5.7 x 10(12) vp/kg, CYP3A2 activity and mRNA levels were suppressed by 45 and 65%, respectively (P < or = 0.01). This continued throughout the study with levels dropping to 36 and 45% of controls by 14 days, respectively (P < or = 0.01). A similar trend was detected for CYP2C11 within this dosing range. Administration of 5.7 x 10(6), 5.7 x 10(8), and 5.7 x 10(9) vp/kg of Ad significantly increased both CYP2C11 protein expression by 86, 71, and 107% and activity 110, 118, and 53%, respectively, above those of animals treated with saline (P < or = 0.01). These results clearly indicate that a single dose of adenovirus significantly alters key drug metabolizing enzymes for an extended period of time and should be investigated further in the context of the design and implementation of clinical trial protocols.
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Affiliation(s)
- Shellie M Callahan
- The University of Texas at Austin, College of Pharmacy, PHR 4.214D, 1 University Station A1920, Austin, TX 78712-1074, USA
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Jacob A, Smolenski A, Lohmann SM, Begum N. MKP-1 expression and stabilization and cGK Iα prevent diabetes- associated abnormalities in VSMC migration. Am J Physiol Cell Physiol 2004; 287:C1077-86. [PMID: 15355857 DOI: 10.1152/ajpcell.00477.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diabetes mellitus is a major risk factor in the development of atherosclerosis and cardiovascular disease conditions, involving intimal injury and enhanced vascular smooth muscle cell (VSMC) migration. We report a mechanistic basis for divergences between insulin’s inhibitory effects on migration of aortic VSMC from control Wistar Kyoto (WKY) rats versus Goto-Kakizaki (GK) diabetic rats. In normal WKY VSMC, insulin increased MAPK phosphatase-1 (MKP-1) expression as well as MKP-1 phosphorylation, which stabilizes it, and inhibited PDGF-mediated MAPK phosphorylation and cell migration. In contrast, basal migration was elevated in GK diabetic VSMCs, and all of insulin’s effects on MKP-1 expression and phosphorylation, MAPK phosphorylation, and PDGF-stimulated migration were markedly inhibited. The critical importance of MKP-1 in insulin inhibition of VSMC migration was evident from several observations. MKP-1 small interfering RNA inhibited MKP-1 expression and abolished insulin inhibition of PDGF-induced VSMC migration. Conversely, adenoviral expression of MKP-1 decreased MAPK phosphorylation and basal migration rate and restored insulin's ability to inhibit PDGF-directed migration in GK diabetic VSMCs. Also, the proteasomal inhibitors lactacystin and MG132 partially restored MKP-1 protein levels in GK diabetic VSMCs and inhibited their migration. Furthermore, GK diabetic aortic VSMCs had reduced cGMP-dependent protein kinase Iα (cGK Iα) levels as well as insulin-dependent, but not sodium nitroprusside-dependent, stimulation of cGMP. Adenoviral expression of cGK Iα enhanced MKP-1 inhibition of MAPK phosphorylation and VSMC migration. We conclude that enhanced VSMC migration in GK diabetic rats is due at least in part to a failure of insulin-stimulated cGMP/cGK Iα signaling, MKP-1 expression, and stabilization and thus MAPK inactivation.
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Affiliation(s)
- Asha Jacob
- Diabetes Rsearch Laboratory, Winthrop University Hospital, Mineola 11501, USA
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Bain JR, Schisler JC, Takeuchi K, Newgard CB, Becker TC. An adenovirus vector for efficient RNA interference-mediated suppression of target genes in insulinoma cells and pancreatic islets of langerhans. Diabetes 2004; 53:2190-4. [PMID: 15331526 DOI: 10.2337/diabetes.53.9.2190] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Silencing gene expression by RNA interference (RNAi) can provide insight into gene function but requires efficient delivery of small interfering RNAs (siRNAs) into cells. Introduction of exogenous nucleic acids can be especially difficult in cultured pancreatic islets. This article describes a method for making recombinant adenoviruses that efficiently drive expression of siRNAs in islet beta-cells and a beta-cell-derived cell line. Transduction with a virus expressing an siRNA specific for GLUT2 reduced GLUT2 mRNA and protein levels by 80% in the INS-1-derived beta-cell line, 832/13, and GLUT2 protein levels by >90% in primary rat islets. Another virus expressing an siRNA specific for glucokinase (GK) caused 80% suppression of GK mRNA and 50% suppression of GK protein levels in 832/13 cells. These experiments validate recombinant adenoviral RNAi vectors as a useful tool for suppression of the expression of specific genes in pancreatic islets and beta-cell lines. Advantages of this approach include 1) the high efficiency of adenovirus-mediated gene transfer in insulinoma cell lines and rat islets and 2) the rapidity with which RNAi constructs can be prepared and tested relative to stable-transfection strategies.
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Affiliation(s)
- James R Bain
- Duke Independence Park Facility, Duke University Medical Center, 4321 Medical Park Dr., Suite 200, Durham, NC 27704, USA
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45
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Bort R, Gómez-Lechón MJ, Castell JV, Jover R. Role of hepatocyte nuclear factor 3γ in the expression of human CYP2C genes. Arch Biochem Biophys 2004; 426:63-72. [PMID: 15130783 DOI: 10.1016/j.abb.2004.03.032] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Revised: 03/24/2004] [Indexed: 11/17/2022]
Abstract
Hepatocyte nuclear factor 3 gamma (HNF-3 gamma) is an important transcription factor for the maintenance of specific liver functions. However, its relevance in the expression of human cytochrome P450 (CYP) genes has not yet been explored. Several HNF3 putative binding sites can be identified in human CYP2C 5'-flanking regions. Gene reporter experiments with proximal promoters revealed that HNF-3 gamma transactivated CYP2C8, CYP2C9, and CYP2C19 (25-, 4-, and 4-fold, respectively), but it did not transactivate CYP2C18. However, overexpression of HNF-3 gamma in hepatoma cells by means of a recombinant adenovirus induced CYP2C9, CYP2C18, and CYP2C19 mRNA (4.5-, 20-, and 50-fold, respectively) but did not activate endogenous CYP2C8. The lack of effect of HNF-3 gamma on endogenous CYP2C8 could be reversed by treating cells with the deacetylase inhibitor, trichostatin A, suggesting the existence of chromatin condensation around functional HNF3 elements in this gene. We conclude that HNF3 gamma is an important transcription factor for the hepatic-specific expression of human CYP2C genes. Our results also evidence that efficient transfection tools, such as adenoviral vectors, may be decisive for assessing the role of transcription factor on chromatin organized genes.
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Affiliation(s)
- Roque Bort
- Unidad de Hepatología Experimental, Centro de Investigación, Hospital Universitario La Fe. Avda. Campanar 21, E-46009, Valencia, Spain
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Topp JD, Gray NW, Gerard RD, Horazdovsky BF. Alsin Is a Rab5 and Rac1 Guanine Nucleotide Exchange Factor. J Biol Chem 2004; 279:24612-23. [PMID: 15033976 DOI: 10.1074/jbc.m313504200] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
ALS2 is the gene mutated in a recessive juvenile form of amyotrophic lateral sclerosis (ALS2). ALS2 encodes a large protein termed alsin, which contains a number of predicted cell signaling and protein trafficking sequence motifs. To gain insight into the overall function of alsin and to begin to evaluate its role in motor neuron maintenance, we examined the subcellular localization of alsin and the biochemical activities associated with its individual subdomains. We found that the Vps9p domain of alsin has Rab5 guanine nucleotide exchange activity. In addition, alsin interacted specifically with and acted as a guanine nucleotide exchange factor for Rac1. Immunofluorescence and fractionation experiments in both fibroblasts and neurons revealed that alsin is a cytosolic protein, with a significant portion associated with small, punctate membrane structures. Many of these membrane structures also contained Rab5 or Rac1. Upon overexpression of full-length alsin, the overexpressed material was largely cytosolic, indicating that the association with membrane structures could be saturated. We also found that alsin was present in membrane ruffles and lamellipodia. These data suggest that alsin is involved in membrane transport events, potentially linking endocytic processes and actin cytoskeleton remodeling.
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Affiliation(s)
- Justin D Topp
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA
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Ferrer-Martínez A, Riera A, Jiménez-Chillarón JC, Herrero P, Moreno F, Gómez-Foix AM. A glucose response element from the S. cerevisiae hexose transporter HXT1 gene is sensitive to glucose in human fibroblasts. J Mol Biol 2004; 338:657-67. [PMID: 15099735 DOI: 10.1016/j.jmb.2004.03.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Revised: 03/05/2004] [Accepted: 03/12/2004] [Indexed: 10/26/2022]
Abstract
Glucose is an essential nutrient, and a regulator of gene expression in eukaryotic cells. Here, a comparative, function-based genomic approach has been used to identify glucose regulatory elements and transduction pathways common to both yeast and mammalian cells. We have isolated a region in the promoter of the Saccharomyces cerevisiae hexose transporter gene HXT1 that conferred glucose sensitivity in yeast, when located upstream of the minimal CYC1 promoter. This element contained binding motifs for Rgt1, a transcriptional modulator involved in the yeast glucose-induction pathway, that were sufficient to elicit glucose responsiveness. The HXT1 regulatory element was then fused to the minimal cytomegalovirus promoter (HXT1-MIN) and inserted into an adenovirus for delivery to human fibroblasts, where it exhibited glucose-dependent transcriptional activation. Glucose action was mimicked by fructose and unrelated to glucose 6-P content, whilst non-metabolizable glucose analogues showed no effect. Activation of AMP kinase by 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranosanide blocked glucose induction, revealing parallels with the yeast glucose-repressing pathway. In contrast, delivery of Rgt1 to fibroblasts did not modify HXT1-MIN responsiveness. Thus, elements of the S.cerevisiae HXT1 gene conserve glucose regulation in human fibroblasts equivalent to the metabolism-dependent, glucose-repressing pathway in yeast. These data suggest that the instructions carried within gene regulatory elements controlling nutrient regulation of gene expression have been conserved throughout evolution.
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Affiliation(s)
- Andreu Ferrer-Martínez
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Martí i Franquès, 1. E-08028-Barcelona, Spain
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Takaishi K, Duplomb L, Wang MY, Li J, Unger RH. Hepatic insig-1 or -2 overexpression reduces lipogenesis in obese Zucker diabetic fatty rats and in fasted/refed normal rats. Proc Natl Acad Sci U S A 2004; 101:7106-11. [PMID: 15096598 PMCID: PMC406473 DOI: 10.1073/pnas.0401715101] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To determine whether the antilipogenic actions of insulin-induced gene 1 (insig-1) demonstrated in cultured preadipocytes also occur in vivo, we infected Zucker diabetic fatty (ZDF) (fa/fa) rats, with recombinant adenovirus containing insig-1 or -2 cDNA. An increase of both proteins appeared in their livers. In control ZDF (fa/fa) rats infected with adenovirus containing the beta-galactosidase (beta-gal) cDNA, triacylglycerols in the liver and plasma rose steeply whereas the insig-infected rats exhibited substantial attenuation of the increase in hepatic steatosis and hyperlipidemia. Insig overexpression was associated with a striking reduction in the elevated level of nuclear sterol regulatory element-binding protein (SREBP)-1c, the activated form of the transcription factor. The mRNA of SREBP-1c lipogenic target enzymes also fell. The mRNA of endogenous insig-1, but not -2a and -2b, was higher in the fatty livers of untreated obese ZDF (fa/fa) rats compared with controls, but the elevation was not sufficient to block the approximately 3-fold increase in SREBP-1c expression and activity. In normal animals, adenovirus-induced overexpression of the insigs reduced the increase in SREBP-1c mRNA and its target enzymes caused by refeeding. The findings demonstrated that both insigs have antilipogenic action when transgenically overexpressed in livers with increased SREBP-1c-mediated lipogenesis. However, the increase in endogenous insig-1 expression associated with augmented lipogenesis may limit it, but is insufficient to prevent it.
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Affiliation(s)
- Kiyosumi Takaishi
- Gifford Laboratories, Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-8854, USA
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Wendeler MW, Praus M, Jung R, Hecking M, Metzig C, Gessner R. Ksp-cadherin is a functional cell–cell adhesion molecule related to LI-cadherin. Exp Cell Res 2004; 294:345-55. [PMID: 15023525 DOI: 10.1016/j.yexcr.2003.11.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Revised: 11/10/2003] [Indexed: 10/26/2022]
Abstract
Ksp- and LI-cadherin are structurally homologous proteins coexpressed with E-cadherin in renal and intestinal epithelia, respectively. Whereas LI-cadherin has been shown to mediate Ca2+-dependent homotypic cell-cell adhesion independent of stable interactions with the cytoskeleton, little is known about the physiological role of Ksp-cadherin. To analyze its potential adhesive and morphoregulatory functions, we expressed murine Ksp-cadherin in CHO cells. In this report, we show that Ksp-cadherin induces homotypic and Ca2+-dependent cell-cell adhesion that can be specifically blocked with antibodies raised against the cadherin repeats EC1 and EC2. Ksp-cadherin mediates about the same quantitative adhesive effect (aggregation index) as LI- and E-cadherin. However, the cellular phenotype induced by Ksp-cadherin resembles more closely that of LI- than E-cadherin. This could reflect our observation, that Ksp-cadherin, as well as LI-cadherin, does not directly interact with beta-catenin. In conclusion, both cadherins are thus not only structurally but also functionally related and may share other functions within their respective epithelia.
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Affiliation(s)
- M W Wendeler
- Institute of Laboratory Medicine and Biochemistry, Virchow-Hospital of Charité Medical School, Humboldt University of Berlin, D-13353 Berlin, Germany
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Kostenuik PJ, Bolon B, Morony S, Daris M, Geng Z, Carter C, Sheng J. Gene therapy with human recombinant osteoprotegerin reverses established osteopenia in ovariectomized mice. Bone 2004; 34:656-64. [PMID: 15050896 DOI: 10.1016/j.bone.2003.12.006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2003] [Revised: 11/25/2003] [Accepted: 12/01/2003] [Indexed: 11/23/2022]
Abstract
Osteoporosis is a chronic condition that is typically treated by the long-term repeated administration of antiresorptive agents. Gene therapy has the potential to deliver protein-based antiresorptive agents without the need for repeated administration. Osteoprotegerin (OPG) is a naturally occuring protein that prevents bone resorption by inhibiting osteoclast formation, function and survival. We tested whether adeno-associated virus (AAV) could deliver OPG at levels that are sufficient to reverse established osteopenia in ovariectomized (OVX) mice without causing liver toxicity. Tibial bone mineral density (BMD) was measured by peripheral quantitative computed tomography (pQCT) in 12-week-old CDF1 mice prior to OVX or sham surgery. Six weeks later, BMD was significantly reduced in OVX mice compared to sham controls or pre-surgery values. Sham and OVX mice were then injected once IV with an AAV vector carrying cDNA for recombinant hOPG (AAV-OPG) or beta-galactosidase (AAV-betaGal). BMD and bone histomorphometry were assessed 10 weeks after treatment. A single injection of AAV-OPG led to the appearance of human OPG (hOPG) in the serum of mice within 7 days, and high serum levels of hOPG were maintained for the duration of the 10-week study. At the end of the study, OVX mice given AAV-OPG had significantly greater tibial BMD compared to age-matched OVX animals given AAV-betaGal. In sham-operated mice, AAV-OPG also significantly increased tibial BMD compared to AAV-betaGal. The increased BMD in AAV-OPG animals was accompanied by significantly increased bone volume and significantly reduced osteoclast surfaces in the proximal tibial metaphysis. Liver histology was normal, and circulating activities of hepatocyte cytosolic enzymes were unaffected by AAV exposure. In an accompanying experiment, young (3-4 weeks) C57BL/6 mice treated once IV with AAV-OPG maintained pharmacologically active levels of OPG in serum for at least 16 months. In summary, a single AAV-OPG treatment reversed established osteopenia in OVX mice without evidence of liver toxicity. AAV delivery appears to be a safe and effective method for producing sustained systemic exposure to OPG.
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Affiliation(s)
- Paul J Kostenuik
- Department of Pathology, Amgen, Thousand Oaks, CA 91320-1799, USA.
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