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Ghrir S, Ben Abbes W, Chourabi A, Abid G, Jallouli S, Elkahoui S, Limam F, Aouani E, Charradi K. Grape seed extract prevents chlorpyrifos-induced toxicity in rat liver through the modulation of phase I detoxification pathway. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:18566-18578. [PMID: 38349500 DOI: 10.1007/s11356-024-32201-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 01/22/2024] [Indexed: 03/09/2024]
Abstract
Chlorpyrifos (CPF) poisoning is a public health problem for which there is not currently any effective prophylaxis. In this study, we investigated the protective effect of grape seed extract (GSE) against CPF-induced hepatotoxicity. Rats were daily treated either with CPF (2 mg/kg) or CPF and GSE (20 mg/kg) for 1 week, sacrificed, and their livers dissected for biochemical, molecular, and histopathological analyses. CPF generated liver dysfunction by altering carbohydrate, lipid, amino acid, ammonia and urea metabolism, and provoked mitochondrial impairment through disturbing tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS), and mitochondrial viability. CPF also induced cholinergic excitotoxicity along with oxidative stress and histopathological alterations. Interestingly, treatment with GSE prevented all the detrimental effects of CPF through the regulation of cytochrome P450 (CYP450) gene expression. Molecular docking analysis indicated that GSE-containing polyphenols acted as epigenetic modulators through inhibiting DNA (cytosine-5)-methyltransferase 1 (DNMT1), thus favoring the CYP2C6 detoxification pathway. Thereby, GSE might be a promising strategy in the protection of the liver against CPF toxicity.
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Affiliation(s)
- Slim Ghrir
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia.
| | - Wassim Ben Abbes
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia
| | - Adam Chourabi
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia
| | - Ghassen Abid
- Laboratory of Legumes and Sustainable Agrosystems, Center of Biotechnology of Borj-Cedria, BP 901, Hammam-Lif 2050, Tunisia
| | - Selim Jallouli
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia
| | - Salem Elkahoui
- Department of Biology, College of Science, University of Ha'il, 81451, Ha'il, Kingdom, Saudi Arabia
| | - Ferid Limam
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia
| | - Ezzedine Aouani
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia
| | - Kamel Charradi
- Laboratory of Bioactive Substances, Center of Biotechnology of Borj-Cedria, BP 901, 2050, Hammam-Lif, Tunisia
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2
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Hernández-Aguirre LE, Peregrino-Uriarte AB, Duarte-Gutiérrez JL, Leyva-Carrillo L, Ezquerra-Brauer JM, Valenzuela-Soto EM, Yepiz-Plascencia G. Shrimp Glucose-6-phosphatase 2 (G6Pase 2): a second isoform of G6Pase in the Pacific white shrimp and regulation of G6Pase 1 and 2 isoforms via HIF-1 during hypoxia and reoxygenation in juveniles. J Bioenerg Biomembr 2023; 55:137-150. [PMID: 36853470 DOI: 10.1007/s10863-023-09960-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/21/2023] [Indexed: 03/01/2023]
Abstract
Animals suffer hypoxia when their oxygen consumption is larger than the oxygen available. Hypoxia affects the white shrimp Penaeus (Litopenaeus) vannamei, both in their natural habitat and in cultivation farms. Shrimp regulates some enzymes that participate in energy production pathways as a strategy to survive during hypoxia. Glucose-6-phosphatase (G6Pase) is key to maintain blood glucose homeostasis through gluconeogenesis and glycogenolysis. We previously reported a shrimp G6Pase gene (G6Pase1) and in this work, we report a second isoform that we named G6Pase2. The expression of the two isoforms was evaluated in oxygen limited conditions and during silencing of the transcription factor HIF-1. High G6Pase activity was detected in hepatopancreas followed by muscle and gills under good oxygen and feeding conditions. Gene expression of both isoforms was analyzed in normoxia, hypoxia and reoxygenation in hepatopancreas and gills, and in HIF-1-silenced shrimp. In fed shrimp with normal dissolved oxygen (DO) (5.0 mg L- 1 DO) the expression of G6Pase1 was detected in gills, but not in hepatopancreas or muscle, while G6Pase2 expression was undetectable in all three tissues. In hepatopancreas, G6Pase1 is induced at 3 and 48 h of hypoxia, while G6Pase2 is down-regulated in the same time points but in reoxygenation, both due to the knock-down of HIF-1. In gills, only G6Pase1 was detected, and was induced by the silencing of HIF-1 only after 3 h of reoxygenation. Therefore, the expression of the two isoforms appears to be regulated by HIF-1 at transcriptional level in response to oxygen deprivation and subsequent recovery of oxygen levels.
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Affiliation(s)
- Laura E Hernández-Aguirre
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C, Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col La Victoria, Hermosillo, Sonora, C.P. 83304, México
| | - Alma B Peregrino-Uriarte
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C, Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col La Victoria, Hermosillo, Sonora, C.P. 83304, México
| | - Jorge L Duarte-Gutiérrez
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C, Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col La Victoria, Hermosillo, Sonora, C.P. 83304, México
| | - Lilia Leyva-Carrillo
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C, Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col La Victoria, Hermosillo, Sonora, C.P. 83304, México
| | - Josafat M Ezquerra-Brauer
- Departamento de Investigación y Posgrado en Alimentos, Universidad de Sonora, Blvd Luis Encinas y Rosales s/n, Hermosillo, Sonora, CP 83000, México
| | - Elisa M Valenzuela-Soto
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C, Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col La Victoria, Hermosillo, Sonora, C.P. 83304, México
| | - Gloria Yepiz-Plascencia
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A.C, Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col La Victoria, Hermosillo, Sonora, C.P. 83304, México.
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3
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Tsumura Y, Tsushima Y, Tamura A, Kato H, Kobayashi T. Disruptions in hepatic glucose metabolism are involved in the diminished efficacy after chronic treatment with glucokinase activator. PLoS One 2022; 17:e0265761. [PMID: 35312718 PMCID: PMC8936481 DOI: 10.1371/journal.pone.0265761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 03/07/2022] [Indexed: 11/19/2022] Open
Abstract
Glucokinase activators are regarded as potent candidates for diabetes treatment, however, in clinical studies on patients with type 2 diabetes, a diminishing efficacy was observed after chronic treatment with them. The mechanism of this reduction has not been elucidated, and whether it is a class effect of glucokinase activators remains inconclusive. Here, we firstly identified a diabetic animal model that shows the diminished efficacy after long-term treatment with MK-0941, a glucokinase activator that exhibited diminished efficacy in a clinical study, and we analyzed the mechanism underlying its diminished efficacy. In addition, we evaluated the long-term efficacy of another glucokinase activator, TMG-123. Goto-Kakizaki rats were treated with MK-0941 and TMG-123 for 24 weeks. The results showed that glycated hemoglobin A1C levels and plasma glucose levels decreased transiently but increased over time with the continuation of treatment in the MK-0941-treated group, while decreased continuously in the TMG-123-treated group. Only in the TMG-123-treated group, higher plasma insulin levels were shown at the later stage of the treatment period. For the mechanism analysis, we conducted a hepatic enzyme assay and liver perfusion study in Goto-Kakizaki rats after chronic treatment with MK-0941 and TMG-123, and revealed that, only in the MK-0941-treated group, the activity of glucose-6-phosphatase was increased, and hepatic glucose utilization was decreased compared to the non-treated group. These data indicate that disruptions in hepatic glucose metabolism are involved in the diminished efficacy of glucokinase activators.
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Affiliation(s)
- Yoshinori Tsumura
- Pharmacology Research Department, Teijin Institute for Bio-medical Research, Teijin Pharma Limited, Hino, Tokyo, Japan
- * E-mail:
| | - Yu Tsushima
- Pharmacology Research Department, Teijin Institute for Bio-medical Research, Teijin Pharma Limited, Hino, Tokyo, Japan
| | - Azusa Tamura
- Pharmacology Research Department, Teijin Institute for Bio-medical Research, Teijin Pharma Limited, Hino, Tokyo, Japan
| | - Hirotsugu Kato
- Pharmacology Research Department, Teijin Institute for Bio-medical Research, Teijin Pharma Limited, Hino, Tokyo, Japan
| | - Tsunefumi Kobayashi
- Pharmacology Research Department, Teijin Institute for Bio-medical Research, Teijin Pharma Limited, Hino, Tokyo, Japan
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4
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Doerksen MJ, Jones RS, Coughtrie MWH, Collier AC. Parameterization of Microsomal and Cytosolic Scaling Factors: Methodological and Biological Considerations for Scalar Derivation and Validation. Eur J Drug Metab Pharmacokinet 2020; 46:173-183. [PMID: 33340340 DOI: 10.1007/s13318-020-00666-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2020] [Indexed: 12/22/2022]
Abstract
Mathematical models that can predict the kinetics of compounds have been increasingly adopted for drug development and risk assessment. Data for these models may be generated from in vitro experimental systems containing enzymes contributing to metabolic clearance, such as subcellular tissue fractions including microsomes and cytosol. Extrapolation from these systems is facilitated by common scaling factors, known as microsomal protein per gram (MPPG) and cytosolic protein per gram (CPPG). Historically, parameterization of MPPG and CPPG has employed the use of recovery factors, commonly benchmarked to cytochromes P450 which work well in some contexts, but could be problematic for other enzymes. Here, we propose absolute quantification of protein content and supplementary assays to evaluate microsomal/cytosolic purity that should be employed. Examples include calculation of microsomal latency by mannose-6-phosphatase activity and immunoblotting of subcellular fractions with fraction-specific markers. Further considerations include tissue source, as disease states can affect enzyme expression and activity, and the methodology used for scalar parameterization. Regional- and organ-specific expression of enzymes, in addition to differences in organ physiology, is another important consideration. Because most efforts have focused on the liver that is, for the most part, homogeneous, derived scalars may not capture the heterogeneity of other major tissues contributing to xenobiotic metabolism including the kidneys and small intestine. Better understanding of these scalars, and how to appropriately derive them from extrahepatic tissues can provide support to the inferences made with physiologically based pharmacokinetic modeling, increase its accuracy in characterizing in vivo drug pharmacokinetics, and improve confidence in go-no-go decisions for clinical trials.
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Affiliation(s)
- Michael J Doerksen
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2405 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Robert S Jones
- Genentech Inc, 1 DNA Way, South San Francisco, California, 94080, USA
| | - Michael W H Coughtrie
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2405 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Abby C Collier
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2405 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada.
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5
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Szelényi P, Somogyi A, Sarnyai F, Zámbó V, Simon-Szabó L, Kereszturi É, Csala M. Microsomal pre-receptor cortisol production is inhibited by resveratrol and epigallocatechin gallate through different mechanisms. Biofactors 2019; 45:236-243. [PMID: 30496642 DOI: 10.1002/biof.1477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 09/24/2018] [Accepted: 10/22/2018] [Indexed: 01/11/2023]
Abstract
Local activation of cortisol in hormone target tissues is a major determinant of glucocorticoid effect. Disorders in this peripheral cortisol metabolism play an important role in the development of metabolic diseases, such as obesity or type 2 diabetes mellitus. Hence, dietary factors influencing the activity of the involved enzymes can have major impacts on the risk of the above diseases. Resveratrol and epigallocatechin gallate (EGCG), two natural polyphenols found in several nutriments and in green tea, respectively, are well-known for their antiobesity and antidiabetic activities. EGCG has been shown to interfere with microsomal cortisol production through decreasing the luminal NADPH:NADP+ ratio. The aim of this study was to clarify if resveratrol also induces such a redox shift or causes any direct enzyme inhibition that influences local cortisol production. Cortisone-cortisol conversions and changes in NADPH levels were monitored in rat liver microsomal vesicles. Cortisol production was inhibited by resveratrol in a concentration dependent manner while the intrinsic reducing and oxidizing capacity as well as the NADPH level inside the ER-derived vesicles remained unaffected. Activity measurements performed in permeabilized microsomes confirmed that resveratrol, unlike EGCG, inhibits 11β-hydroxysteroid dehydrogenase type 1 directly. Long-term moderation of pre-receptor cortisol production likely contributes to the beneficial health effects of both polyphenols. © 2018 BioFactors, 45(2):236-243, 2019.
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Affiliation(s)
- Péter Szelényi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Anna Somogyi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Farkas Sarnyai
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Veronika Zámbó
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Laura Simon-Szabó
- Pathobiochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University (MTA-SE), Budapest, Hungary
| | - Éva Kereszturi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
| | - Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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6
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De Freitas L, Jimenez D, Pimentel S, Mitaine-Offer AC, Pouységu L, Quideau S, Paululat T, Gonzalez-Mujica F, Rojas LB, Rodríguez M, Lacaille-Dubois MA. Triterpene saponins from Billia rosea. PHYTOCHEMISTRY 2017; 141:105-113. [PMID: 28599241 DOI: 10.1016/j.phytochem.2017.04.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 04/25/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isolated from the seeds of Billia rosea (Planch. & Linden) C. Ulloa & P. Jørg. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments (1H, 13C, DEPT, COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC) and mass spectrometry as (3β,21β,22α)-3-[(2-O-β-D-glucopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21-[((2E,6S)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl)oxy]-22-(acetyloxy)-24-hydroxyolean-12-en-28-oic acid, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-xylopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-glucopyranoside, (3β,21β,22α)-3-[(2-O-β-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranoside, and dipteroside A. Billiosides B and C exhibited moderate effects when tested as hepatic glucose-6-phosphatase inhibitors and as glucose intestinal absorption inhibitors, using in situ rat intestinal segments.
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Affiliation(s)
- Luis De Freitas
- Laboratoire de Pharmacognosie, PEPITE EA 4267, UFR des Sciences de Santé, Université de Bourgogne Franche-Comté, 7, Bd. Jeanne d'Arc, BP 87900, F-21079 Dijon Cedex, France; Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Caracas 47102, Venezuela
| | - Doris Jimenez
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Caracas 47102, Venezuela
| | - Sherley Pimentel
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Caracas 47102, Venezuela
| | - Anne-Claire Mitaine-Offer
- Laboratoire de Pharmacognosie, PEPITE EA 4267, UFR des Sciences de Santé, Université de Bourgogne Franche-Comté, 7, Bd. Jeanne d'Arc, BP 87900, F-21079 Dijon Cedex, France
| | - Laurent Pouységu
- Institut des Sciences Moléculaires, CNRS-UMR 5255 et Institut Européen de Chimie et Biologie, Université de Bordeaux, 2 Rue Robert Escarpit, 33607 Pessac Cedex, France
| | - Stéphane Quideau
- Institut des Sciences Moléculaires, CNRS-UMR 5255 et Institut Européen de Chimie et Biologie, Université de Bordeaux, 2 Rue Robert Escarpit, 33607 Pessac Cedex, France
| | - Thomas Paululat
- Universität Siegen, OC-II, Naturwissenschaftlich-Technische Fakultät, Adolf-Reichwein-Str. 2, D-57076 Siegen, Germany
| | - Freddy Gonzalez-Mujica
- Sección de Bioquímica Médica, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela, Caracas 50587, Venezuela
| | - Luis B Rojas
- Laboratorio de Productos Naturales, Departamento de Quimica, Facultad de Ciencias, Universidad de los Andes, Mérida 5101, Venezuela
| | - María Rodríguez
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Caracas 47102, Venezuela
| | - Marie-Aleth Lacaille-Dubois
- Laboratoire de Pharmacognosie, PEPITE EA 4267, UFR des Sciences de Santé, Université de Bourgogne Franche-Comté, 7, Bd. Jeanne d'Arc, BP 87900, F-21079 Dijon Cedex, France.
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7
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Wang Y, Wang H, Li M, Gao Z, Zhang S. Identification, expression and regulation of amphioxus G6Pase gene with an emphasis on origin of liver. Gen Comp Endocrinol 2015; 214:9-16. [PMID: 25745818 DOI: 10.1016/j.ygcen.2014.12.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/25/2014] [Accepted: 12/28/2014] [Indexed: 10/23/2022]
Abstract
Vertebrate glucose-6-phosphatase (G6Pase) consists of three isozymes: G6Pase-I, G6Pase-II and G6Pase-III. Despite extensive study on G6Pases in vertebrates, information regarding expression and regulation of G6Pase genes is rather limited in invertebrates. Here we report the identification of G6Pase gene in amphioxus Branchiostoma japonicum, which is abundantly expressed in the digestive diverticulum and ovary in a tissue-specific manner. The phylogenetic and genomic structure analyses reveal that amphioxus G6Pase bears close resemblance to vertebrate G6Pase-III and represents the archetype of vertebrate G6Pase from which the vertebrate G6Pase isoforms may be originated by 2 rounds of genome duplication during vertebrate evolution. We also demonstrate that GH treatment induces a closely similar expression pattern and trend of g6pases in both zebrafish and amphioxus, and that G6Pase activity in amphioxus digestive diverticulum is subjected to regulation of feeding and fasting as observed in vertebrates. Collectively, all these provide functional evidences supporting the notion that the digestive diverticulum is the liver homologue playing a key role in maintaining the glucose homeostasis in amphioxus.
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Affiliation(s)
- Yu Wang
- Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao 266003, China
| | - Hui Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Mengyang Li
- Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao 266003, China
| | - Zhan Gao
- Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao 266003, China
| | - Shicui Zhang
- Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
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8
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Szelényi P, Révész K, Konta L, Tüttõ A, Mandl J, Kereszturi É, Csala M. Inhibition of microsomal cortisol production by (-)-epigallocatechin-3-gallate through a redox shift in the endoplasmic reticulum--a potential new target for treating obesity-related diseases. Biofactors 2013; 39:534-41. [PMID: 23554216 DOI: 10.1002/biof.1095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/09/2013] [Indexed: 01/18/2023]
Abstract
Conversion of cortisone to cortisol by 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) in the endoplasmic reticulum (ER) of the target cells is a major determinant of glucocorticoid action, and plays an important role in the development of obesity-related diseases. Inhibition of 11βHSD1 activity is, therefore, considered as a promising novel strategy for the treatment of metabolic syndrome and diabetes. Tea flavanols and their major representative, epigallocatechin gallate are known as antiobesity and antidiabetic agents. Their impacts on blood glucose level, hepatic glucose production, and insulin responsiveness resemble those observed on inhibition or depletion of 11βHSD1. We aimed to study the effect of epigallocatechin gallate on 11βHSD1 activity in ER-derived rat liver microsomes by measuring cortisone and cortisol with HPLC. Cortisol production was efficiently suppressed in a concentration dependent manner in intact microsomal vesicles. However, this effect was abolished by membrane permeabilization; and the three proteins involved in the overall process (11βHSD1, hexose 6-phosphate dehydrogenase, and glucose 6-phosphate transporter) were not or only mildly affected. Further investigation revealed the oxidation of luminal NADPH to NADP⁺, which attenuates cortisone reduction and favors cortisol oxidation in this compartment. Such a redox shift in the ER lumen might contribute to the beneficial health effects of tea flavanols and should be regarded as a promising strategy for the development of novel selective 11βHSD1 inhibitors to treat obesity-related diseases.
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Affiliation(s)
- Péter Szelényi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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9
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Révész K, Tóth B, Staines AG, Coughtrie MWH, Mandl J, Csala M. Luminal accumulation of newly synthesized morphine-3-glucuronide in rat liver microsomal vesicles. Biofactors 2013; 39:271-8. [PMID: 23281118 DOI: 10.1002/biof.1067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/16/2012] [Indexed: 01/23/2023]
Abstract
Morphine is converted to morphine 3-β-D-glucuronide (M3G) by the UDP-glucuronosyltransferase Ugt2b1 in the endoplasmic reticulum (ER) of rat liver. Because of its luminal localization, UGT activity requires UDP-glucuronate import and glucuronide export across the ER membrane. The former transport is generally considered to be rate limiting and to explain the latency of UGT activities in intact microsomal vesicles. However, some observations indicate that the release of bulky glucuronides, such as M3G, might also be rate limiting for glucuronidation. This assumption was tested by characterizing the transport of M3G and its distribution between the intra- and extravesicular spaces during synthesis in rat liver microsomes. The amount of vesicle-associated M3G was measured using rapid filtration and LC-MS measurement. Our results reveal a remarkable accumulation of newly synthesized M3G in the microsomal lumen above the equilibrium. The transport showed a linear concentration-dependence in a wide range (5-200 μM). Therefore, the build-up of high (about 20 μM) luminal M3G concentration could adjust the rate of release to that of synthesis (44.85 ± 4.08 pmol/min/mg protein) during the conjugation of 100 μM morphine. These data can explain earlier findings indicative of separate intracellular pools of M3G in rat liver. Accumulation of bulky glucuronides in the ER lumen might also play an important role in their targeting and in the control of biliary excretion.
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Affiliation(s)
- Katalin Révész
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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10
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Bermúdez J, Rodríguez M, Hasegawa M, González-Mujica F, Duque S, Ito Y. (6R,9S)-6″-(4″-Hydroxybenzoyl)-Roseoside, a New Megastigmane Derivative from Ouratea polyantha and its Effect on Hepatic Glucose-6-phosphatase. Nat Prod Commun 2012. [DOI: 10.1177/1934578x1200700802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A new megastigmane derivative, (6 R,9 S)–6′-(4″-hydroxybenzoyl)-roseoside (1) and two known compounds, the biflavoneagathisflavone (2) and 4-hydroxy-benzoic acid (3) were isolated and purified from leaves and stems of Ouratea polyantha Engl. Agathisflavone was isolated in a single high-speed counter-current chromatography run, while the megastigmane was purified in two steps, by using a combination of high-speed countercurrent chromatography and analytical column chromatography. All structures were elucidated on the basis of spectral evidence and comparison with literature data. Compound 1 was characterized by [α]D20, UV-Vis, IR, MS, 1H NMR, 13C NMR, HMQC, HMBC, COSY and NOESY. Compounds 1 and 2 showed an inhibitory effect of 63.6 and 13.7% on the G-6-Pase intact microsomes, respectively.
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Affiliation(s)
- Jairo Bermúdez
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela. Apartado Postal 47102. Caracas, Venezuela
- Bioseparation Technology Laboratory, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center drive, Building 10, Room 8N230, MD 20892–1762, USA
| | - María Rodríguez
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela. Apartado Postal 47102. Caracas, Venezuela
| | - Masahisa Hasegawa
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela. Apartado Postal 47102. Caracas, Venezuela
| | - Freddy González-Mujica
- Sección de Bioquímica Médica, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela. Apartado Postal 50587. Caracas, Venezuela
| | - Sandra Duque
- Sección de Bioquímica Médica, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela. Apartado Postal 50587. Caracas, Venezuela
| | - Yoichiro Ito
- Bioseparation Technology Laboratory, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center drive, Building 10, Room 8N230, MD 20892–1762, USA
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11
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Margittai É, Löw P, Stiller I, Greco A, Garcia-Manteiga JM, Pengo N, Benedetti A, Sitia R, Bánhegyi G. Production of H₂O₂ in the endoplasmic reticulum promotes in vivo disulfide bond formation. Antioxid Redox Signal 2012; 16:1088-99. [PMID: 22369093 DOI: 10.1089/ars.2011.4221] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AIMS Oxidative protein folding in the luminal compartment of endoplasmic reticulum (ER) is thought to be accompanied by the generation of H₂O₂, as side-product of disulfide bond formation. We aimed to examine the role of H₂O₂ produced in the lumen, which on one hand can lead to redox imbalance and hence can contribute to ER stress caused by overproduction of secretory proteins; on the other hand, as an excellent electron acceptor, H₂O₂ might serve as an additional pro-oxidant in physiological oxidative folding. RESULTS Stimulation of H₂O₂ production in the hepatic ER resulted in a decrease in microsomal GSH and protein-thiol contents and in a redox shift of certain luminal oxidoreductases in mice. The oxidative effect, accompanied by moderate signs of ER stress and reversible dilation of ER cisternae, was prevented by concomitant reducing treatment. The imbalance also affected the redox state of pyridine nucleotides in the ER. Antibody producing cells artificially engineered with powerful luminal H₂O₂ eliminating system showed diminished secretion of mature antibody polymers, while incomplete antibody monomers/dimers were accumulated and/or secreted. INNOVATION Evidence are provided by using in vivo models that hydrogen peroxide can promote disulfide bond formation in the ER. CONCLUSION The results indicate that local H₂O₂ production promotes, while quenching of H₂O₂ impairs disulfide formation. The contribution of H₂O₂ to disulfide bond formation previously observed in vitro can be also shown in cellular and in vivo systems.
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Affiliation(s)
- Éva Margittai
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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12
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Ahmed A, Rabbitt E, Brady T, Brown C, Guest P, Bujalska IJ, Doig C, Newsome PN, Hubscher S, Elias E, Adams DH, Tomlinson JW, Stewart PM. A switch in hepatic cortisol metabolism across the spectrum of non alcoholic fatty liver disease. PLoS One 2012; 7:e29531. [PMID: 22363403 PMCID: PMC3282715 DOI: 10.1371/journal.pone.0029531] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 11/30/2011] [Indexed: 12/13/2022] Open
Abstract
Context Non alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. NAFLD represents a spectrum of liver disease ranging from reversible hepatic steatosis, to non alcoholic steato-hepatitis (NASH) and cirrhosis. The potential role of glucocorticoids (GC) in the pathogenesis of NAFLD is highlighted in patients with GC excess, Cushing's syndrome, who develop central adiposity, insulin resistance and in 20% of cases, NAFLD. Although in most cases of NAFLD, circulating cortisol levels are normal, hepatic cortisol availability is controlled by enzymes that regenerate cortisol (F) from inactive cortisone (E) (11β-hydroxysteroid dehydrogenase type 1, 11β-HSD1), or inactivate cortisol through A-ring metabolism (5α- and 5β-reductase, 5αR and 5βR). Objective and Methods In vitro studies defined 11β-HSD1 expression in normal and NASH liver samples. We then characterised hepatic cortisol metabolism in 16 patients with histologically proven NAFLD compared to 32 obese controls using gas chromatographic analysis of 24 hour urine collection and plasma cortisol generation profile following oral cortisone. Results In patients with steatosis 5αR activity was increased, with a decrease in hepatic 11β-HSD1 activity. Total cortisol metabolites were increased in this group consistent with increased GC production rate. In contrast, in patients with NASH, 11β-HSD1 activity was increased both in comparison to patients with steatosis, and controls. Endorsing these findings, 11β-HSD1 mRNA and immunostaining was markedly increased in NASH patients in peri septal hepatocytes and within CD68 positive macrophages within inflamed cirrhotic septa. Conclusion Patients with hepatic steatosis have increased clearance and decreased hepatic regeneration of cortisol and we propose that this may represent a protective mechanism to decrease local GC availability to preserve hepatic metabolic phenotype. With progression to NASH, increased 11β-HSD1 activity and consequent cortisol regeneration may serve to limit hepatic inflammation.
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Affiliation(s)
- Adeeba Ahmed
- Centre for Endocrinology, Diabetes and Metabolism, Institute of Biomedical Research, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Elizabeth Rabbitt
- Centre for Endocrinology, Diabetes and Metabolism, Institute of Biomedical Research, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Theresa Brady
- Wellcome Trust Clinical Research Facility, University Hospital Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Claire Brown
- Wellcome Trust Clinical Research Facility, University Hospital Birmingham NHS Foundation Trust, Birmingham, United Kingdom
| | - Peter Guest
- Radiology, University Hospital Birmingham NHS Foundation, Trust, Birmingham, United Kingdom
| | - Iwona J. Bujalska
- Centre for Endocrinology, Diabetes and Metabolism, Institute of Biomedical Research, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Craig Doig
- Centre for Endocrinology, Diabetes and Metabolism, Institute of Biomedical Research, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Philip N. Newsome
- Centre for Liver Research and NIHR Biomedical Research Unit in Liver Disease, University Hospital Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, United Kingdom
| | - Stefan Hubscher
- Pathology, University Hospital Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, United Kingdom
| | - Elwyn Elias
- Centre for Liver Research and NIHR Biomedical Research Unit in Liver Disease, University Hospital Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, United Kingdom
| | - David H. Adams
- Centre for Liver Research and NIHR Biomedical Research Unit in Liver Disease, University Hospital Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, United Kingdom
| | - Jeremy W. Tomlinson
- Centre for Endocrinology, Diabetes and Metabolism, Institute of Biomedical Research, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Paul M. Stewart
- Centre for Endocrinology, Diabetes and Metabolism, Institute of Biomedical Research, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
- * E-mail:
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13
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Bruzual De Abreu M, Temraz A, Malafronte N, Gonzalez-Mujica F, Duque S, Braca A. Phenolic Derivatives from Ruprechtia polystachya and Their Inhibitory Activities on the Glucose-6-phosphatase System. Chem Biodivers 2011; 8:2126-34. [DOI: 10.1002/cbdv.201000334] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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de Oliveira MC, Torrezan R, da Costa CEM, Ambiel CR, Constantin RP, Ishii-Iwamoto EL, Salgueiro-Pagadigorria CL. Changes in calcium fluxes in mitochondria, microsomes, and plasma membrane vesicles of livers from monosodium L-glutamate-obese rats. Metabolism 2011; 60:1433-41. [PMID: 21489575 DOI: 10.1016/j.metabol.2011.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 02/09/2011] [Accepted: 02/17/2011] [Indexed: 01/11/2023]
Abstract
The purpose of this work was to evaluate if the fat liver accumulation interferes with intracellular calcium fluxes and the liver glycogenolytic response to a calcium-mobilizing α(1)-adrenergic agonist, phenylephrine. The animal model of monosodium L-glutamate (MSG)-induced obesity was used. The adult rats develop obesity and steatosis. Calcium fluxes were evaluated through measuring the (45)Ca(2+) uptake by liver microsomes, inside-out plasma membrane, and mitochondria. In the liver, assessments were performed on the calcium-dependent glycogenolytic response to phenylephrine and the glycogen contents. The Ca(2+) uptake by microsomes and plasma membrane vesicles was reduced in livers from obese rats as a result of reduction in the Ca(2+)-ATPase activities. In addition, the plasma membrane Na(+)/K(+)-ATPase was reduced. All these matched effects could contribute to elevated resting intracellular calcium levels in the hepatocytes. Livers from obese rats, albeit smaller and with similar glycogen contents to those of control rats, released higher amounts of glucose in response to phenylephrine infusion, which corroborates these observations. Mitochondria from obese rats exhibited a higher capacity of retaining calcium, a phenomenon that could be attributed to a minor susceptibility of the mitochondrial permeability transition pore opening.
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Affiliation(s)
- Monique Cristine de Oliveira
- Laboratory of Biological Oxidations, Department of Biochemistry, University of Maringá, 87020900 Maringá, Brazil
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15
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Nakaoka F, Sasakawa Y, Yamamoto K, Nakao M, Nakamura M, Tong C, Fukuhama C, Kagawa K. Anti-diabetic effects of globin digest and its active ingredient Leu-Ser-Glu-Leu in ICR mice, streptozotocin-induced diabetic mice and KK-Ay mice. Life Sci 2010; 86:424-34. [DOI: 10.1016/j.lfs.2010.01.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 01/14/2010] [Accepted: 01/19/2010] [Indexed: 10/19/2022]
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16
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García C, Barriga A, Díaz JC, Lagos M, Lagos N. Route of metabolization and detoxication of paralytic shellfish toxins in humans. Toxicon 2010; 55:135-44. [DOI: 10.1016/j.toxicon.2009.07.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Revised: 05/16/2009] [Accepted: 07/14/2009] [Indexed: 11/28/2022]
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17
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Carrasco D, Méndez J, Braca A, De Leo M, González-Mujica F, Duque S. Effect of Flavonoids from Exellodendron coriaceum (Chrysobalanaceae) on Glucose-6-Phosphatase. Nat Prod Commun 2009. [DOI: 10.1177/1934578x0900401209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
From the n-butanol extract of the aerial parts of Exellodendron coriaceum (Benth.) Prance the flavonoids quercetin-3-O-β-D-galactopyranoside (1), quercetin-3-O-α-L-arabinopyranoside (2), quercetin-3-O-α-L-rhamnopyranosyl-(1→2)-α-L-rhamnopyranoside (3), and quercetin-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside (4) were isolated. Additionally from this extract three flavonoids were isolated and partially characterized as quercetin glycosides. All these compounds were tested for their hypoglycemic activity using the glucose-6-phosphatase microsomal hepatic system. The flavonoids inhibited the activity of the enzyme when intact microsomes were used, the highest percentage of inhibition being 65%. To the best of our knowledge, this is the first report of chemical and biological activity of E. coriaceum.
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Affiliation(s)
- Diana Carrasco
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47102, Caracas 1020-A, Venezuela
| | - Jeannette Méndez
- Laboratorio de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47102, Caracas 1020-A, Venezuela
| | - Alessandra Braca
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 33, 56126, Pisa, Italy
| | - Marinella De Leo
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 33, 56126, Pisa, Italy
| | - Freddy González-Mujica
- Instituto de Medicina Experimental, Sección de Bioquímica Médica, Facultad de Medicina, Universidad Central de Venezuela. Caracas, Venezuela
| | - Sandra Duque
- Laboratorio de Bioensayos José María Benitez. Grupo de Productos Naturales, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela. Caracas, Venezuela
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18
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García C, Rodriguez-Navarro A, Díaz JC, Torres R, Lagos N. Evidence of in vitro glucuronidation and enzymatic transformation of paralytic shellfish toxins by healthy human liver microsomes fraction. Toxicon 2009; 53:206-13. [DOI: 10.1016/j.toxicon.2008.10.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 10/16/2008] [Accepted: 10/20/2008] [Indexed: 11/29/2022]
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19
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Margittai É, Löw P, Szarka A, Csala M, Benedetti A, Bánhegyi G. Intraluminal hydrogen peroxide induces a permeability change of the endoplasmic reticulum membrane. FEBS Lett 2008; 582:4131-6. [DOI: 10.1016/j.febslet.2008.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 11/01/2008] [Accepted: 11/12/2008] [Indexed: 01/08/2023]
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20
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Margittai E, Bánhegyi G. Isocitrate dehydrogenase: A NADPH-generating enzyme in the lumen of the endoplasmic reticulum. Arch Biochem Biophys 2008; 471:184-90. [PMID: 18201546 DOI: 10.1016/j.abb.2007.12.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 12/21/2007] [Accepted: 12/30/2007] [Indexed: 11/26/2022]
Abstract
The aim of the present study was the investigation of the occurrence of NADPH-generating pathways in the endoplasmic reticulum others then hexose-6-phosphate dehydrogenase. A significant isocitrate and a moderate malate-dependent NADP+ reduction were observed in endoplasmic reticulum-derived rat liver microsomes. The isocitrate-dependent activity was very likely attributable to the appearance of the cytosolic isocitrate dehydrogenase isozyme in the lumen. The isocitrate dehydrogenase activity of microsomes was present in the luminal fraction; it showed a strong preference towards NADP+ versus NAD+, and it was almost completely latent. Antibodies against the cytosolic isoform of isocitrate dehydrogenase immunorevealed a microsomal protein of identical molecular weight; the microsomal enzyme showed similar kinetic parameters and oxalomalate inhibition as the cytosolic one. Measurable luminal isocitrate dehydrogenase activity was also present in microsomes from rat epididymal fat. The results suggest that isocitrate dehydrogenase is an important NADPH-generating enzyme in the endoplasmic reticulum.
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Affiliation(s)
- Eva Margittai
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Pathobiochemistry Research Group of The Hungarian Academy of Sciences, 1444 Budapest, P.O. Box 260, Budapest, Hungary
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21
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Walker EA, Ahmed A, Lavery GG, Tomlinson JW, Kim SY, Cooper MS, Ride JP, Hughes BA, Shackleton CHL, McKiernan P, Elias E, Chou JY, Stewart PM. 11β-Hydroxysteroid Dehydrogenase Type 1 Regulation by Intracellular Glucose 6-Phosphate Provides Evidence for a Novel Link between Glucose Metabolism and Hypothalamo-Pituitary-Adrenal Axis Function. J Biol Chem 2007; 282:27030-27036. [PMID: 17588937 DOI: 10.1074/jbc.m704144200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microsomal glucose-6-phosphatase-alpha (G6Pase-alpha) and glucose 6-phosphate transporter (G6PT) work together to increase blood glucose concentrations by performing the terminal step in both glycogenolysis and gluconeogenesis. Deficiency of the G6PT in liver gives rise to glycogen storage disease type 1b (GSD1b), whereas deficiency of G6Pase-alpha leads to GSD1a. G6Pase-alpha shares its substrate (glucose 6-phosphate; G6P) with hexose-6-phosphate-dehydrogenase (H6PDH), a microsomal enzyme that regenerates NADPH within the endoplasmic reticulum lumen, thereby conferring reductase activity upon 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). 11beta-HSD1 interconverts hormonally active C11beta-hydroxy steroids (cortisol in humans and corticosterone in rodents) to inactive C11-oxo steroids (cortisone and 11-dehydrocorticosterone, respectively). In vivo reductase activity predominates, generating active glucocorticoid. We hypothesized that substrate (G6P) availability to H6PDH in patients with GSD1b and GSD1a will decrease or increase 11beta-HSD1 reductase activity, respectively. We investigated 11beta-HSD1 activity in GSD1b and GSD1a mice and in two patients with GSD1b and five patients diagnosed with GSD1a. We confirmed our hypothesis by assessing 11beta-HSD1 in vivo and in vitro, revealing a significant decrease in reductase activity in GSD1b animals and patients, whereas GSD1a patients showed a marked increase in activity. The cellular trafficking of G6P therefore directly regulates 11beta-HSD1 reductase activity and provides a novel link between glucose metabolism and function of the hypothalamo-pituitary-adrenal axis.
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Affiliation(s)
- Elizabeth A Walker
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Adeeba Ahmed
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Gareth G Lavery
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Jeremy W Tomlinson
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - So Youn Kim
- NICHD, National Institutes of Health, Bethesda, Maryland, 20892
| | - Mark S Cooper
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Jonathan P Ride
- Biological Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Beverly A Hughes
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Cedric H L Shackleton
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Patrick McKiernan
- Liver Unit, Birmingham Children's Hospital, Birmingham B4 6NH, United Kingdom
| | - Elwyn Elias
- Liver and Hepatobiliary Unit, Queen Elizabeth Hospital, Edgbaston, Birmingham, B15 2TH, United Kingdom
| | - Janice Y Chou
- NICHD, National Institutes of Health, Bethesda, Maryland, 20892
| | - Paul M Stewart
- Endocrinology, Division of Medical Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TH, United Kingdom.
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22
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Forsyth L, Scott HM, Howatson A, Busuttil A, Hume R, Burchell A. Genetic variation in hepatic glucose-6-phosphatase system genes in cases of sudden infant death syndrome. J Pathol 2007; 212:112-20. [PMID: 17354259 DOI: 10.1002/path.2147] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Genetic deficiencies of the hepatic glucose-6-phosphatase system, either of the enzyme (G6PC1) or of the glucose-6-phosphate transporter (G6PT1), result in fasting hypoglycaemia. Low hepatic G6PC1 activities were previously reported in a few term sudden infant death syndrome (SIDS) infants and assumed to be due to G6PC1 genetic deficiencies. In preterm infants, failures of postnatal activation of G6PC1 expression suggest disordered development as a novel cause of decreased G6PC1 activity in SIDS. G6PC1 and G6PT1 functional and mutational analysis was investigated in SIDS and non-SIDS infants. G6PC1 hepatic activity was abnormally low in 98 SIDS (preterm, n=13; term, n=85), and non-SIDS preterm infants (n=35) compared to term non-SIDS infants (n=29) and adults (n=9). Mean glycogen levels were elevated, except in term non-SIDS infants. A novel G6PT1 promoter polymorphism, 259C --> T was found; the - 259*T allele frequency was greater in term SIDS infants (n=140) than in term control infants (n=119) and preterm SIDS infants (n=30). Heterozygous and homozygous prevalence of 259C --> T was 38.6% and 7.1%, respectively, in term SIDS infants. In cell-based expression systems, the presence of - 259T in the promoter decreased basal luciferase activity by 3.2-fold compared to - 259C. Glucose-6-phosphatase latency in hepatic microsomes was elevated (indicating decreased G6PT1 function) in heterozygous and homozygous - 259T states. Delayed postnatal appearance of hepatic glucose-6-phosphatase in infants makes them vulnerable to hypoglycaemic episodes and this may occur in some SIDS infants. However, SIDS may be an association of more complex phenotypes in which several genes interact with multiple environmental factors. A UK-wide DNA Biobank of samples from all infant deaths, with an accompanying epidemiological database, should be established by pathologists to allow cumulative data to be collected from multiple genetic investigations on the same large cohort of samples, with the aim of selection of the best combination of genetic markers to predict unexpected infant death.
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Affiliation(s)
- L Forsyth
- Maternal and Child Health Sciences, University of Dundee, UK
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23
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Lim PLK, Tan W, Latchoumycandane C, Mok WC, Khoo YM, Lee HS, Sattabongkot J, Beerheide W, Lim SG, Tan TMC, Boelsterli UA. Molecular and functional characterization of drug-metabolizing enzymes and transporter expression in the novel spontaneously immortalized human hepatocyte line HC-04. Toxicol In Vitro 2007; 21:1390-401. [PMID: 17590308 DOI: 10.1016/j.tiv.2007.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 03/20/2007] [Accepted: 05/02/2007] [Indexed: 02/02/2023]
Abstract
In toxicological research, immortalized human hepatocytes provide a useful alternative to primary hepatocytes because interindividual variability in the expression of drug-metabolizing enzymes and drug transporters can largely be eliminated. However, it is essential that the cell line retain the original phenotype. The purpose of this study was to characterize a novel spontaneously immortalized human hepatocyte cell line, HC-04, with respect to the transcript and functional protein expression profile for the major drug-metabolizing enzymes and transmembrane transporters. HC-04 cells retained hepatocyte-specific function including albumin production and ornithine transcarbamoylase and glucose-6-phosphatase activity. Most of the major CYP forms were expressed at basal levels and responsive to inducing agents. In particular, CYP3A4 was expressed abundantly, and HC-04 cells were able to metabolize the CYP3A4 probe, midazolam, at a rate similar to primary human hepatocytes. Furthermore, the major human sulfotransferase and UDP-glucuronosyltransferase forms, as well as members of the ABC and SLC transporter superfamilies, nuclear receptors, and hepatic transcription factors were also expressed. HC-04 cells readily responded to standard hepatotoxicants that are dependent on CYP-mediated bioactivation, while another, tumor-derived cell line remained refractory to the drug challenge. Collectively, HC-04 cells provide a reliable, stable, and reproducible model for biomechanistic studies in drug toxicology.
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Affiliation(s)
- Priscilla L K Lim
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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24
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Sloop KW, Showalter AD, Cox AL, Cao JXC, Siesky AM, Zhang HY, Irizarry AR, Murray SF, Booten SL, Finger EA, McKay RA, Monia BP, Bhanot S, Michael MD. Specific reduction of hepatic glucose 6-phosphate transporter-1 ameliorates diabetes while avoiding complications of glycogen storage disease. J Biol Chem 2007; 282:19113-21. [PMID: 17478431 DOI: 10.1074/jbc.m610759200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
D-Glucose-6-phosphatase is a key regulator of endogenous glucose production, and its inhibition may improve glucose control in type 2 diabetes. Herein, 2'-O-(2-methoxy)ethyl-modified phosphorothioate antisense oligonucleotides (ASOs) specific to the glucose 6-phosphate transporter-1 (G6PT1) enabled reduction of hepatic D-Glu-6-phosphatase activity in diabetic ob/ob mice. Treatment with G6PT1 ASOs decreased G6PT1 expression, reduced G6PT1 activity, blunted glucagon-stimulated glucose production, and lowered plasma glucose concentration in a dose-dependent manner. In contrast to G6PT1 knock-out mice and patients with glycogen storage disease, excess hepatic and renal glycogen accumulation, hyperlipidemia, neutropenia, and elevations in plasma lactate and uric acid did not occur. In addition, hypoglycemia was not observed in animals during extended periods of fasting, and the ability of G6PT1 ASO-treated mice to recover from an exogenous insulin challenge was not impaired. Together, these results demonstrate that effective glucose lowering by G6PT1 inhibitors can be achieved without adversely affecting carbohydrate and lipid metabolism.
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Affiliation(s)
- Kyle W Sloop
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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Csala M, Margittai É, Senesi S, Gamberucci A, Bánhegyi G, Mandl J, Benedetti A. Inhibition of hepatic glucose 6-phosphatase system by the green tea flavanol epigallocatechin gallate. FEBS Lett 2007; 581:1693-8. [DOI: 10.1016/j.febslet.2007.03.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 03/10/2007] [Accepted: 03/21/2007] [Indexed: 01/16/2023]
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26
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Révész K, Tütto A, Margittai E, Bánhegyi G, Magyar JE, Mandl J, Csala M. Glucuronide transport across the endoplasmic reticulum membrane is inhibited by epigallocatechin gallate and other green tea polyphenols. Int J Biochem Cell Biol 2007; 39:922-30. [PMID: 17317271 DOI: 10.1016/j.biocel.2007.01.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 01/03/2007] [Accepted: 01/08/2007] [Indexed: 11/22/2022]
Abstract
Toxic endogenous or exogenous compounds can be inactivated by various conjugation reactions. Glucuronidation (i.e. conjugation with glucuronate) is especially important due to the large number of drugs and chemical carcinogens that are detoxified through this pathway. Stable and harmless glucuronides can be reactivated by enzymatic hydrolysis thus inhibitors of glucuronidase activity reduce the risk of chemical carcinogenesis. The aim of this study was to reveal whether this mechanism contributes to the anti-cancer effect of green tea flavanols, which has been shown in various animal models. Therefore, we investigated the effect of these polyphenols on deglucuronidation in rat liver microsomes and in Hepa 1c1c7 mouse hepatoma cells, using 4-methylumbelliferyl glucuronide as model substrate. Tea flavanols inhibited beta-glucuronidase in intact vesicles, where glucuronide transport across the microsomal membrane is rate-limiting, but were almost ineffective in permeabilized vesicles. Epigallocatechin gallate, the major green tea flavanol was shown to have a concentration-dependent inhibitory effect on both beta-glucuronidase activity and glucuronide transport in native vesicles. Epigallocatechin gallate also inhibited beta-glucuronidase activity in native Hepa 1c1c7 mouse hepatoma cells, while failed to affect the enzyme in alamethicin-permeabilized cells, where the endoplasmic membrane barrier was eliminated. Our findings indicate that tea flavanols inhibit deglucuronidation in the endoplasmic reticulum at the glucuronide transport stage. This phenomenon might potentially contribute to the cancer-preventing dietary or pharmacological effect attributed to these catechins.
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Affiliation(s)
- Katalin Révész
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Endoplasmic Reticulum Research Group of The Hungarian Academy of Sciences, Semmelweis University, H-1444 Budapest, P.O. Box 260, Hungary
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Kobayashi T, Sleeman J, Coughtrie M, Burchell B. Molecular and functional characterization of microsomal UDP-glucuronic acid uptake by members of the nucleotide sugar transporter (NST) family. Biochem J 2006; 400:281-9. [PMID: 16965264 PMCID: PMC1652819 DOI: 10.1042/bj20060429] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Transport of the co-substrate UDPGA (UDP-glucuronic acid) into the lumen of the endoplasmic reticulum is an essential step in glucuronidation reactions due to the intraluminal location of the catalytic site of the enzyme UGT (UDP-glucuronosyltransferase). In the present study, we have characterized the function of several NSTs (nucleotide sugar transporters) and UGTs as potential carriers of UDPGA for glucuronidation reactions. UDPGlcNAc (UDP-N-acetylglucosamine)-dependent UDPGA uptake was found both in rat liver microsomes and in microsomes prepared from the rat hepatoma cell line H4IIE. The latency of UGT activity in microsomes derived from rat liver and V79 cells expressing UGT1A6 correlated well with mannose-6-phosphatase latency, confirming the UGT in the recombinant cells retained a physiology similar to rat liver microsomes. In the present study, four cDNAs coding for NSTs were obtained; two were previously reported (UGTrel1 and UGTrel7) and two newly identified (huYEA4 and huYEA4S). Localization of NSTs within the human genome sequence revealed that huYEA4S is an alternatively spliced form of huYEA4. All the cloned NSTs were stably expressed in V79 (Chinese hamster fibroblast) cells, and were able to transport UDPGA after preloading of isolated microsomal vesicles with UDPGlcNAc. The highest uptake was seen with UGTrel7, which displayed a V(max) approx. 1% of rat liver microsomes. Treatment of H4IIE cells with beta-naphthoflavone induced UGT protein expression but did not affect the rate of UDPGA uptake. Furthermore, microsomes from UGT1-deficient Gunn rat liver showed UDPGA uptake similar to those from control rats. These data show that NSTs can act as UDPGA transporters for glucuronidation reactions, and indicate that UGTs of the 1A family do not function as UDPGA carriers in microsomes. The cell line H4IIE is a useful model for the study of UDPGA transporters for glucuronidation reactions.
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Affiliation(s)
- Tsutomu Kobayashi
- Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital and Medical School, DUNDEE DD1 9SY, Scotland, U.K
| | - Judith E. Sleeman
- Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital and Medical School, DUNDEE DD1 9SY, Scotland, U.K
| | - Michael W. H. Coughtrie
- Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital and Medical School, DUNDEE DD1 9SY, Scotland, U.K
- To whom correspondence should be addressed (email )
| | - Brian Burchell
- Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital and Medical School, DUNDEE DD1 9SY, Scotland, U.K
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Gamberucci A, Konta L, Colucci A, Giunti R, Magyar JE, Mandl J, Bánhegyi G, Benedetti A, Csala M. Green tea flavonols inhibit glucosidase II. Biochem Pharmacol 2006; 72:640-6. [PMID: 16806089 DOI: 10.1016/j.bcp.2006.05.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 05/19/2006] [Accepted: 05/19/2006] [Indexed: 10/24/2022]
Abstract
Green tea is getting into the focus of scientific interest due to its beneficial health effects, most of which are attributed to its catechin content. Polyphenolic tea catechins have antioxidant, antiproliferative, antiangiogenic and proapoptotic effects, which makes them promising anticancer compounds. Other poly-hydroxy molecules have similar antitumor potentials through the inhibition of glucosidase II, which affects the glycoprotein maturation and quality control in the endoplasmic reticulum. We investigated the effect of tea catechins on glucosidase II activity in rat liver microsomes using 4-methylumbelliferyl glucoside and 4-nitrophenyl glucoside as substrates. A concentration-dependent inhibition with non-competitive kinetics was found. The IC50 and Ki values for certain tea catechins were comparable with those of N-butyldeoxynojirimycin, the widely used glucosidase inhibitor. The possible interference of tea catechins with the glycoprotein processing in the endoplasmic reticulum should be considered as a potential mechanism of their dietary or pharmacological effects.
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Affiliation(s)
- Alessandra Gamberucci
- Department of Physiopathology, Experimental Medicine and Public Health, University of Siena, and Unit for Development of Biomedical Research, Santa Maria alle Scotte Hospital, Siena, Italy
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29
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Nardai G, Stadler K, Papp E, Korcsmáros T, Jakus J, Csermely P. Diabetic changes in the redox status of the microsomal protein folding machinery. Biochem Biophys Res Commun 2006; 334:787-95. [PMID: 16023999 DOI: 10.1016/j.bbrc.2005.06.172] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2005] [Accepted: 06/27/2005] [Indexed: 01/19/2023]
Abstract
Changes in assisted protein folding are largely unexplored in diabetes. In the present studies, we have identified a reductive shift in the redox status of rat liver microsomes after 4 weeks of streptozotocin-induced diabetes. This change was reflected by a significant increase in the total- and protein-sulfhydryl content, as well as in the free sulfhydryl groups of the major protein disulfide isomerases (PDIs), the 58 kDa PDI and the 57 kDa ERp57 but not other chaperones. A parallel decrease of the protein-disulfide oxidoreductase activity was detected in the microsomal fraction of diabetic livers. The oxidant of PDI, Ero1-Lalpha showed a more oxidized status in diabetic rats. Our results reveal major changes in the redox status of the endoplasmic reticulum and its redox chaperones in diabetic rats, which may contribute to the defective protein secretion of the diabetic liver.
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Affiliation(s)
- Gábor Nardai
- Department of Medical Chemistry, Semmelweis University, P.O. Box 260, H-1444 Budapest 8, Hungary
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30
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Pagadigorria CLS, Marcon F, Kelmer-Bracht AM, Bracht A, Ishii-Iwamoto EL. Effects of methotrexate on calcium flux in rat liver mitochondria, microsomes and plasma membrane vesicles. Comp Biochem Physiol C Toxicol Pharmacol 2006; 143:340-8. [PMID: 16730477 DOI: 10.1016/j.cbpc.2006.03.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 03/25/2006] [Accepted: 03/26/2006] [Indexed: 11/30/2022]
Abstract
The metabolic effects of methotrexate in perfused livers are similar to those exerted by hormones acting through Ca(2+)-dependent mechanisms. The aim of the present study was to determine whether the effects of methotrexate are mediated by a direct action on cellular Ca(2+) fluxes. Methotrexate did not affect the ATP-dependent (45)Ca(2+) uptake by mitochondria, microsomes and inside-out plasma membrane vesicles and Ca(2+) efflux from plasma membrane vesicles. However, methotrexate was able to stimulate (45)Ca(2+) release from preloaded microsomes. The amount of Ca(2+) released by methotrexate was similar to that induced by IP(3). Methotrexate could be acting through the capacitative calcium entry mechanism.
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Affiliation(s)
- Clairce L S Pagadigorria
- Laboratory of Biological Oxidations, Department of Biochemistry, University of Maringá, 87020900 Maringá, Brazil
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31
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Lizák B, Czegle I, Csala M, Benedetti A, Mandl J, Bánhegyi G. Translocon pores in the endoplasmic reticulum are permeable to small anions. Am J Physiol Cell Physiol 2006; 291:C511-7. [PMID: 16611737 DOI: 10.1152/ajpcell.00274.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Contribution of translocon peptide channels to the permeation of low molecular mass anions was investigated in rat liver microsomes. Puromycin, which purges translocon pores of nascent polypeptides, creating additional empty pores, raised the microsomal uptake of radiolabeled UDP-glucuronic acid, while it did not increase the uptake of glucose-6-phosphate or glutathione. The role of translocon pores in the transport of small anions was also investigated by measuring the effect of puromycin on the activity of microsomal enzymes with intraluminal active sites. The mannose-6-phosphatase activity of glucose-6-phosphatase and the activity of UDP-glucuronosyltransferase were elevated upon addition of puromycin, but glucose-6-phosphatase and beta-glucuronidase activities were not changed. The increase in enzyme activities was due to a better access of the substrates to the luminal compartment rather than to activation of the enzymes. Antibody against Sec61 translocon component decreased the activity of UDP-glucuronosyltransferase and antagonized the effect of puromycin. Similarly, the addition of the puromycin antagonist anisomycin or treatments of microsomes, resulting in the release of attached ribosomes, prevented the puromycin-dependent increase in the activity. Mannose-6-phosphatase and UDP-glucuronosyltransferase activities of smooth microsomal vesicles showed higher basal latencies that were not affected by puromycin. In conclusion, translationally inactive, ribosome-bound translocons allow small anions to cross the endoplasmic reticulum membrane. This pathway can contribute to the nonspecific substrate supply of enzymes with intraluminal active centers.
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Affiliation(s)
- Beáta Lizák
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, PO Box 260, 1444 Budapest, Hungary
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32
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Rodriguez de Sotillo DV, Hadley M, Sotillo JE. Insulin receptor exon 11+/− is expressed in Zucker (fa/fa) rats, and chlorogenic acid modifies their plasma insulin and liver protein and DNA. J Nutr Biochem 2006; 17:63-71. [PMID: 16169204 DOI: 10.1016/j.jnutbio.2005.06.004] [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] [Received: 03/23/2005] [Revised: 05/06/2005] [Accepted: 06/13/2005] [Indexed: 10/25/2022]
Abstract
In vivo studies confirmed that chlorogenic acid (CGA) improved glucose tolerance and mineral pool distribution in obese Zucker (fa/fa) rats. We found a significant decrease (P<.05) in postprandial blood glucose concentrations, which may have been due to an improved sensitivity to insulin. Impaired glucose tolerance and insulin resistance have been associated with differences in the hepatic mRNA expression of the spliced variants of the insulin receptor at exon 11. Spliced variants of the insulin receptor have not been studied in obese Zucker (fa/fa) rats, and no information exists about the effects of CGA in vivo as a possible insulin sensitizer. Thus, we studied the in vivo effect of CGA on plasma insulin concentrations during a glucose tolerance test, liver protein and DNA concentrations, the hepatic activity of glucose-6-phosphatase (G-6-PASE) and the mRNA expression of the two variants of the insulin receptor at exon 11. Zucker (fa/fa) rats were implanted with jugular vein catheters. Chlorogenic acid was administered (5 mg/kg body weight per day) for 3 weeks via intravenous infusion. In the CGA-treated group, areas under the curve (AUC) for blood glucose and plasma insulin improved (P<.005), and the protein and DNA concentrations in the liver increased (P<.05). No significant differences (P>.05) were found between groups for the hepatic G-6-PASE activity. The insulin receptor exon 11(+) and the exon 11(-) variants were expressed in the liver of Zucker (fa/fa) rats without significant changes (P>.05). Chlorogenic acid improved some cellular mechanisms that are stimulated by insulin.
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Wang D, Wei Y, Schmoll D, Maclean KN, Pagliassotti MJ. Endoplasmic reticulum stress increases glucose-6-phosphatase and glucose cycling in liver cells. Endocrinology 2006; 147:350-8. [PMID: 16223860 DOI: 10.1210/en.2005-1014] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Impaired regulation of hepatic glucose production is a characteristic feature of the metabolic syndrome, a cluster of diseases that includes obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. It has been proposed that sustained endoplasmic reticulum stress, which appears to occur in obesity and diabetes, modulates insulin action in the liver. In this study, we show that experimental induction of endoplasmic reticulum stress increases expression and activity of glucose-6-phosphatase and the capacity for glucose release and glucose cycling in primary rat hepatocytes and H4IIE liver cells. Increased expression of the catalytic subunit of glucose-6-phosphatase was largely a result of increased transcription. Deletion analysis of the glucose-6-phosphatase promoter identified an endoplasmic reticulum stress-responsive region located between -233 and -187 with respect to the transcriptional start site. Experimental induction of endoplasmic reticulum stress increased the activity of c-jun N-terminal kinase. Prevention of endoplasmic reticulum stress-mediated activation of c-jun N-terminal kinase reduced the expression of the catalytic subunit of glucose-6-phosphatase, glucose-6-phosphatase activity, glucose release, and glucose cycling. These data demonstrate that sustained endoplasmic reticulum stress in the hepatocyte provokes adaptations, mediated in part via activation of c-jun N-terminal kinase, that act to increase hepatocellular capacity for glucose release and glucose cycling.
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Affiliation(s)
- Dong Wang
- Departments of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado 80523-1571, USA
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34
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Piccirella S, Czegle I, Lizák B, Margittai E, Senesi S, Papp E, Csala M, Fulceri R, Csermely P, Mandl J, Benedetti A, Bánhegyi G. Uncoupled redox systems in the lumen of the endoplasmic reticulum. Pyridine nucleotides stay reduced in an oxidative environment. J Biol Chem 2005; 281:4671-7. [PMID: 16373343 DOI: 10.1074/jbc.m509406200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The redox state of the intraluminal pyridine nucleotide pool was investigated in rat liver microsomal vesicles. The vesicles showed cortisone reductase activity in the absence of added reductants, which was dependent on the integrity of the membrane. The intraluminal pyridine nucleotide pool could be oxidized by the addition of cortisone or metyrapone but not of glutathione. On the other hand, intraluminal pyridine nucleotides were slightly reduced by cortisol or glucose 6-phosphate, although glutathione was completely ineffective. Redox state of microsomal protein thiols/disulfides was not altered either by manipulations affecting the redox state of pyridine nucleotides or by the addition of NAD(P)+ or NAD(P)H. The uncoupling of the thiol/disulfide and NAD(P)+/NAD(P)H redox couples was not because of their subcompartmentation, because enzymes responsible for the intraluminal oxidoreduction of pyridine nucleotides were distributed equally in smooth and rough microsomal subfractions. Instead, the phenomenon can be explained by the negligible representation of glutathione reductase in the endoplasmic reticulum lumen. The results demonstrated the separate existence of two redox systems in the endoplasmic reticulum lumen, which explains the contemporary functioning of oxidative folding and of powerful reductive reactions.
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Affiliation(s)
- Simona Piccirella
- Department of Medical Chemistry, Molecular Biology, and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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Papp E, Nardai G, Mandl J, Bánhegyi G, Csermely P. FAD oxidizes the ERO1-PDI electron transfer chain: the role of membrane integrity. Biochem Biophys Res Commun 2005; 338:938-45. [PMID: 16246310 DOI: 10.1016/j.bbrc.2005.10.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2005] [Accepted: 10/07/2005] [Indexed: 11/29/2022]
Abstract
The molecular steps of the electron transfer in the endoplasmic reticulum from the secreted proteins during their oxidation are relatively unknown. We present here that flavine adenine dinucleotide (FAD) is a powerful oxidizer of the oxidoreductase system, Ero1 and PDI, besides the proteins of rat liver microsomes and HepG2 hepatoma cells. Inhibition of FAD transport hindered the action of FAD. Microsomal membrane integrity was mandatory for all FAD-related oxidation steps downstream of Ero1. The PDI inhibitor bacitracin could inhibit FAD-mediated oxidation of microsomal proteins and PDI, but did not hinder the FAD-driven oxidation of Ero1. Our data demonstrated that Ero1 can utilize FAD as an electron acceptor and that FAD-driven protein oxidation goes through the Ero1-PDI pathway and requires the integrity of the endoplasmic reticulum membrane. Our findings prompt further studies to elucidate the membrane-dependent steps of PDI oxidation and the role of FAD in redox folding.
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Affiliation(s)
- Eszter Papp
- Department of Medical Chemistry, Semmelweis University, H-1088 Budapest, Hungary
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36
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Csala M, Senesi S, Bánhegyi G, Mandl J, Benedetti A. Characterization of sulfate transport in the hepatic endoplasmic reticulum. Arch Biochem Biophys 2005; 440:173-80. [PMID: 16055076 DOI: 10.1016/j.abb.2005.06.017] [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] [Received: 04/22/2005] [Revised: 06/21/2005] [Accepted: 06/22/2005] [Indexed: 10/25/2022]
Abstract
The transport of sulfate ion across the endoplasmic reticulum membrane was investigated using rapid filtration and light scattering assays. We found a protein-mediated, bi-directional, low-affinity, and high-capacity, facilitative sulfate transport in rat liver microsomes, which could be inhibited by the prototypical anion transport inhibitor, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. It was resistant to various phosphate transport inhibitors and was not influenced by high concentration of phosphate or pyrophosphate, which is contradictory to involvement of phosphate transporters. It was sensitive to S3483 that has been reported to inhibit the glucose 6-phosphate transporter (G6PT), but the weak competition between sulfate and glucose 6-phosphate did not confirm the participation of this transporter. Moreover, the comparison of the activity and S3483 sensitivity of sulfate transport in microsomes prepared from G6PT-overexpressing or wild type COS-7 cells did not show any significant difference. Our results indicate that sulfate fluxes in the endoplasmic reticulum are mediated by a novel, S3483-sensitive transport pathway(s).
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Affiliation(s)
- Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Endoplasmic Reticulum Research Group of The Hungarian Academy of Sciences, H-1444, Budapest, P.O. Box 260, Hungary
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37
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Sukhodub AL, Burchell A. Preparation of intact microsomes from cultured mammalian H4IIE cells. J Pharmacol Toxicol Methods 2005; 52:330-4. [PMID: 16023872 DOI: 10.1016/j.vascn.2005.04.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 04/26/2005] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Mammalian cell culture is widely used for the cloning and expression of insoluble proteins. The established methods of sub-cellular fractionation of tissues are not always directly suitable for the sub-cellular fractionation of cultured cells. In this study we have optimized the conditions for the preparation of microsomal fractions from cultured cells with the aim of isolating intact vesicles that are suitable for the assay of transport proteins and lumenal enzymes. METHODS H4IIE cell cultures were used as a convenient model with high latency of internal endoplasmic reticulum enzyme glucose-6-phosphatase towards mannose-6-phosphate. Also 7-ethoxyresorufin O-deethylase (EROD) activity was determined as a reflection of the state of monooxygenase system. RESULTS The variations in a number of homogenization strokes and buffer composition revealed that one homogenization stroke in glass homogenizer with 0.25 M sucrose, 5 mM HEPES, pH 7.4 buffer provides the best latency/activity ratio for homogenates, but for the isolation of microsomes the higher number of strokes (10) as well as low-osmotic buffer (5 mM HEPES, pH 7.4) are needed. However EROD activity is largely reduced in the preparations using buffers containing sucrose, so 5 mM HEPES buffer is recommended as the most suitable to study the microsomal reactions in H4IIE cells. DISCUSSION The isolation of microsomes was followed by the significant proteolytic breakdown of the glucose-6-phosphatase enzyme. It is recommended to use cell culture homogenates for assays when possible.
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Affiliation(s)
- Andrey L Sukhodub
- School of Biological Sciences, University of Portsmouth, St. Michaels Building, White Swan Road, Portsmouth, Hampshire, PO1 2DT, England, UK
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Ghosh A, Cheung YY, Mansfield BC, Chou JY. Brain contains a functional glucose-6-phosphatase complex capable of endogenous glucose production. J Biol Chem 2005; 280:11114-9. [PMID: 15661744 DOI: 10.1074/jbc.m410894200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Glucose is absolutely essential for the survival and function of the brain. In our current understanding, there is no endogenous glucose production in the brain, and it is totally dependent upon blood glucose. This glucose is generated between meals by the hydrolysis of glucose-6-phosphate (Glc-6-P) in the liver and the kidney. Recently, we reported a ubiquitously expressed Glc-6-P hydrolase, glucose-6-phosphatase-beta (Glc-6-Pase-beta), that can couple with the Glc-6-P transporter to hydrolyze Glc-6-P to glucose in the terminal stages of glycogenolysis and gluconeogenesis. Here we show that astrocytes, the main reservoir of brain glycogen, express both the Glc-6-Pase-beta and Glc-6-P transporter activities and that these activities can couple to form an active Glc-6-Pase complex, suggesting that astrocytes may provide an endogenous source of brain glucose.
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Affiliation(s)
- Abhijit Ghosh
- Section on Cellular Differentiation, Heritable Disorders Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892-1830, USA
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Gonzalez-Mujica F, Motta N, Estrada O, Perdomo E, Méndez J, Hasegawa M. Inhibition of hepatic neoglucogenesis and glucose-6-phosphatase by quercetin 3-O-α(2″-galloyl)rhamnoside isolated fromBauhinia megalandra leaves. Phytother Res 2005; 19:624-7. [PMID: 16161025 DOI: 10.1002/ptr.1704] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In intact microsomes, quercetin 3-O-alpha-(2''-galloyl)rhamnoside (QGR) inhibits glucose-6-phosphatase (G-6-Pase) in a concentration-dependent manner. QGR increased the G-6-Pase K(m) for glucose-6-phosphate without change in the V(max). The flavonol did not change the kinetic parameters of disrupted microsomal G-6-Pase or intact or disrupted microsomal G-6-Pase pyrophosphatase (PPase) activity. This result allowed the conclusion that QGR competitively inhibits the glucose-6-phosphate (G-6-P) transporter (T1) without affecting the catalytic subunit or the phosphate/pyrophosphate transporter (T2) of the G-6-Pase system.QGR strongly inhibits the neoglucogenic capacity of rat liver slices incubated in a Krebs-Ringer bicarbonate buffer, supplemented with lactate and oleate saturated albumin. The QGR G-6-Pase inhibition might explain the decrease in the liver slice neoglucogenic capacity and, in turn, could reduce glucose levels in diabetic patients.
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Affiliation(s)
- Freddy Gonzalez-Mujica
- Sección de Bioquímica Médica, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela.
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40
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Estrada O, Hasegawa M, Gonzalez-Mujíca F, Motta N, Perdomo E, Solorzano A, Méndez J, Méndez B, Zea EG. Evaluation of flavonoids fromBauhinia megalandra leaves as inhibitors of glucose-6-phosphatase system. Phytother Res 2005; 19:859-63. [PMID: 16261515 DOI: 10.1002/ptr.1703] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
From the methanol extract of Bauhinia megalandra fresh leaves, eight flavonoids were isolated and evaluated by rat liver microsomal glucose-6-phosphatase (G-6-Pase) bioassay, which might be a useful methodology for screening antihyperglycaemic substances. All the flavonoids assayed showed an inhibitory effect on the intact microsomal G-6-Pase: quercetin and kaempferol exhibited the lowest effect; astilbin, quercetin 3-O-alpha-rhamnoside, kaempferol 3-O-alpha-rhamnoside and quercetin 3-O-alpha-arabinoside an intermediate effect. The highest inhibitory activity was shown by quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''galloyl)rhamnoside. None of the flavonoids mentioned above showed an inhibitory effect on the disrupted microsomal G-6-Pase. Quercetin 3-O-alpha-(2''-galloyl)rhamnoside and kaempferol 3-O-alpha-(2''-galloyl)rhamnoside exhibited the lowest IC50 of all the flavonoids assayed. Also, the phlorizin IC50 is reported.
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Affiliation(s)
- Omar Estrada
- Centro de Química Orgánica, Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Apartado postal 47102, Caracas, Venezuela.
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Angaroni CJ, de Kremer RD, Argaraña CE, Paschini-Capra AE, Giner-Ayala AN, Pezza RJ, Pan CJ, Chou JY. Glycogen storage disease type Ia in Argentina: two novel glucose-6-phosphatase mutations affecting protein stability. Mol Genet Metab 2004; 83:276-9. [PMID: 15542400 DOI: 10.1016/j.ymgme.2004.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2004] [Revised: 06/19/2004] [Accepted: 06/21/2004] [Indexed: 11/21/2022]
Abstract
Glycogen storage disease type Ia (GSD-Ia) is caused by deleterious mutations in the glucose-6-phosphatase gene (G6PC). A molecular study of this gene was carried out in 11 Argentinean patients from 8 unrelated families. Four missense (p.Gln54Pro, p.Arg83Cys, p.Thr16Arg, and p.Tyr209Cys) and one deletion (c.79delC) mutations have been identified. Two novel mutations, p.Thr16Arg (c.47C>G) located within the amino-terminal domain and p.Tyr209Cys (c.626A>G) situated in the sixth transmembrane helix, were uncovered in this study. Site-directed mutagenesis and transient expression assays demonstrated that both p.Thr16Arg and p.Tyr209Cys mutations abolished enzymatic activity as well as reduced G6Pase stability.
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Affiliation(s)
- Celia J Angaroni
- Centro de Estudio de las Metabolopatías Congénitas, CEMECO, Cátedra de Clínica Pediátrica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Hospital de Niños de la Santísima Trinidad, Córdoba, Argentina.
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42
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Metzger S, Nusair S, Planer D, Barash V, Pappo O, Shilyansky J, Chajek-Shaul T. Inhibition of hepatic gluconeogenesis and enhanced glucose uptake contribute to the development of hypoglycemia in mice bearing interleukin-1beta- secreting tumor. Endocrinology 2004; 145:5150-6. [PMID: 15297440 DOI: 10.1210/en.2004-0323] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mice bearing IL-1beta-secreting tumor were used to study the chronic effect of IL-1beta on glucose metabolism. Mice were injected with syngeneic tumor cells transduced with the human IL-1beta gene. Serum IL-1beta levels increased exponentially with time. Secretion of IL-1beta from the developed tumors was associated with decreased food consumption, reduced body weight, and reduced blood glucose levels. Body composition analysis revealed that IL-1beta caused a significant loss in fat tissue without affecting lean body mass and water content. Hepatic phosphoenolpyruvate carboxykinase and glucose-6-phosphatase activities and mRNA levels of these enzymes were reduced, and 2-deoxy-glucose uptake by peripheral tissues was enhanced. mRNA levels of glucose transporters (Gluts) in the liver were determined by real-time PCR analysis. Glut-3 mRNA levels were up-regulated by IL-1beta. Glut-1 and Glut-4 mRNA levels in IL-1beta mice were similar to mRNA levels in pair-fed mice bearing nonsecreting tumor. mRNA level of Glut-2, the major Glut of the liver, was down-regulated by IL-1beta. We concluded that both decreased glucose production by the liver and enhanced glucose disposal lead to the development of hypoglycemia in mice bearing IL-1beta-secreting tumor. The observed changes in expression of hepatic Gluts that are not dependent on insulin may contribute to the increased glucose uptake.
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Affiliation(s)
- Shulamit Metzger
- Department of Medicine, Hadassah University Hospital, Mount Scopus, P.O. Box 24035, Jerusalem 91240, Israel
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43
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Csala M, Staines AG, Bánhegyi G, Mandl J, Coughtrie MWH, Burchell B. Evidence for multiple glucuronide transporters in rat liver microsomes. Biochem Pharmacol 2004; 68:1353-62. [PMID: 15345325 DOI: 10.1016/j.bcp.2004.05.055] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Accepted: 05/26/2004] [Indexed: 12/01/2022]
Abstract
The transport of glucuronides across the endoplasmic reticulum membrane is an important step in the overall process of biotransformation, although the mechanism remains unclear and the participating transporters are unidentified. Using a rapid filtration assay in combination with liquid chromatography-mass spectrometry, we measured the transport of a variety of beta-D-glucuronides in rat liver microsomes and investigated the substrate specificity of the participating transporter(s) by inhibition studies. Time-dependent and bi-directional transport of phenolphthalein glucuronide was detected and the kinetic parameters for transport were determined. The K(m) and V(max) values of high affinity transport were 26microM and 3.9nmol/min/mg protein, respectively. Phenolphthalein glucuronide transport was inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and N-ethylmaleimide. Transport inhibition studies revealed competition between three glucuronides: phenolphthalein glucuronide, estradiol 17-glucuronide and naphthol AS-BI glucuronide indicating that they share a common transporter in the endoplasmic reticulum membrane. Their transport was inhibited by phenolphthalein, but was not affected by p-nitrophenyl glucuronide, naphthyl glucuronide or d-glucuronate. Morphine 3-glucuronide transport was not inhibited by any of the latter four compounds or by phenolphthalein glucuronide. This novel experimental approach has produced data consistent with the presence of multiple (at least three) transporters catalyzing the transport of glucuronides through the endoplasmic reticulum membrane. These data also indicate that the size and/or shape of the aglycone rather than the glucuronic acid moiety per se is an important determinant of transporter specificity.
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Affiliation(s)
- Miklós Csala
- Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland.
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44
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Heled Y, Shapiro Y, Shani Y, Moran DS, Langzam L, Barash V, Sampson SR, Meyerovitch J. Physical exercise enhances hepatic insulin signaling and inhibits phosphoenolpyruvate carboxykinase activity in diabetes-prone Psammomys obesus. Metabolism 2004; 53:836-41. [PMID: 15254873 DOI: 10.1016/j.metabol.2004.02.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We have shown that physical exercise enhances insulin sensitivity of skeletal muscle in diabetes-prone Psammomys-obesus. In this study, we examined the effect of physical exercise on the liver of these animals. Three groups of animals were exposed to a 4-week protocol; high-energy diet (CH), high-energy diet and exercising (EH), and low-energy diet (CL). Different groups were studied either in a fed state or after an overnight fast, 30 minutes after intraperitoneal (IP) injection of 1 U insulin. Hepatic phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) activity was measured. Insulin signaling response was examined after insulin injection in the fast state by analyzing tyrosine phosphorylation of insulin receptor (IR) and the association between insulin receptor substrate-1 (IRS-1) and IRS-2 with phosphatidylinositol 3 kinase (PI3-K). After 4 weeks, none of the EH animals became diabetic, whereas all the CH animals became diabetic. PEPCK activity in the fed state was higher in the CH group compared with the CL and EH groups (480 +/- 28 nmol/min/mg protein, 280 +/- 30 nmol/min/mg protein, and 208 +/- 13 nmol/min/mg protein, respectively) (P < .02). G6Pase activity was higher in the CH and EH groups compared with the CL group (261 +/- 54 nmol/min/mg protein, 251 +/- 34 nmol/min/mg protein, and 75 +/- 32 nmol/min/mg protein, respectively) (P < .01). After insulin administration in the fast state, tyrosine phosphorylation of IR and association of IRS-2 with PI3-K were higher in the EH and CL groups than in the CH group. We conclude that exercise improves in vivo hepatic insulin sensitivity in diabetes-prone Psammomys-obesus.
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Affiliation(s)
- Yuval Heled
- Heller Institute of Medical Research and Pediatric Division, Sheba Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Shieh JJ, Pan CJ, Mansfield BC, Chou JY. A Potential New Role for Muscle in Blood Glucose Homeostasis. J Biol Chem 2004; 279:26215-9. [PMID: 15087461 DOI: 10.1074/jbc.m402036200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The breakdown of tissue glycogen into glucose is critical for blood glucose homeostasis between meals. In the final steps of glycogenolysis, intracellular glucose 6-phosphate (Glc-6-P) is transported into the endoplasmic reticulum where it is hydrolyzed to glucose by glucose-6-phosphatase (Glc-6-Pase). Although the majority of body glycogen is stored in the muscle, the current dogma holds that Glc-6-Pase (now named Glc-6-Pase-alpha) is expressed only in the liver, kidney, and intestine, implying that muscle glycogen cannot contribute to interprandial blood glucose homeostasis. Recently we reported a second Glc-6-P hydrolase, Glc-6-Pase-beta. Glc-6-Pase-beta shares kinetic and structural similarities to Glc-6-Pase-alpha and couples with the Glc-6-P transporter to form an active Glc-6-Pase complex (Shieh, J.-J., Pan, C.-J., Mansfield, B. C., and Chou, J. Y. (2003) J. Biol. Chem. 278, 47098-47103). Here we demonstrate that muscle expresses both Glc-6-Pase-beta and Glc-6-P transporter and that they can couple to form an active Glc-6-Pase complex. Our data suggest that muscle may have a previously unrecognized role in interprandial glucose homeostasis.
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Affiliation(s)
- Jeng-Jer Shieh
- Section on Cellular Differentiation, Heritable Disorders Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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Huang A, Chen Y, Wang X, Zhao S, Su N, White DW. Functional silencing of hepatic microsomal glucose-6-phosphatase gene expression in vivo by adenovirus-mediated delivery of short hairpin RNA. FEBS Lett 2004; 558:69-73. [PMID: 14759518 DOI: 10.1016/s0014-5793(03)01499-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Revised: 11/21/2003] [Accepted: 12/15/2003] [Indexed: 12/12/2022]
Abstract
An expression cassette containing mouse U6 polymerase III promoter directing expression of short hairpin RNA (shRNA) targeting murine microsomal glucose-6-phosphatase (G6P) transcript was generated. This construct was packaged into an adenoviral (AdV) backbone and viral stocks generated. Mice injected intravenously with AdV-G6PshRNA exhibited a significant reduction in postprandial glucose levels and had significantly elevated steady-state hepatic glycogen stores. Target gene silencing was confirmed by measurements demonstrating a significant reduction in both hepatic G6P transcript level and phosphohydrolase activity. These findings provide evidence that AdV delivery of expressed shRNA can be a productive tool to explore gene function in vivo.
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Affiliation(s)
- Alan Huang
- Millennium Pharmaceuticals, 75 Sidney St., Cambridge, MA 02139, USA
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Salgueiro-Pagadigorria CL, Kelmer-Bracht AM, Bracht A, Ishii-Iwamoto EL. Naproxen affects Ca2+ fluxes in mitochondria, microsomes and plasma membrane vesicles. Chem Biol Interact 2004; 147:49-63. [PMID: 14726152 DOI: 10.1016/j.cbi.2003.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
There is substantial evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) affect cellular processes regulated by Ca(2+) ions, including the metabolic responses of the liver to Ca(2+)-dependent hormones. The aim of the present study was to determine whether the effects of naproxen are mediated by a direct action on cellular Ca(2+) fluxes. The effects of naproxen on 45Ca(2+) fluxes in mitochondria, microsomes and inside-out plasma membrane vesicles were examined. Naproxen strongly impaired the mitochondrial capacity to retain 45Ca(2+) and inhibited also ATP-dependent 45Ca(2+) uptake by microsomes. Naproxen did not modify 45Ca(2+) uptake by inside-out plasma membrane vesicles, but it inhibited the hexokinase/glucose-induced Ca(2+) efflux from preloaded vesicles. Additional assays performed in isolated mitochondria revealed that naproxen causes mitochondrial uncoupling and swelling in the presence of Ca(2+) ions. These effects were prevented by EGTA, ruthenium red and cyclosporin A, indicating that naproxen acts synergistically with Ca(2+) ions by promoting the mitochondrial permeability transition. The experimental results suggest that naproxen may impair the metabolic responses to Ca(2+)-dependent hormones acting by at least two mechanisms: (1) by interfering with the supply of external Ca(2+) through a direct action on the plasma membrane Ca(2+) influx, and (2) by affecting the refilling of the agonist-sensitive internal stores, including endoplasmic reticulum and mitochondria.
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Varsányi M, Szarka A, Papp E, Makai D, Nardai G, Fulceri R, Csermely P, Mandl J, Benedetti A, Bánhegyi G. FAD transport and FAD-dependent protein thiol oxidation in rat liver microsomes. J Biol Chem 2003; 279:3370-4. [PMID: 14612450 DOI: 10.1074/jbc.m307783200] [Citation(s) in RCA: 22] [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
The transport of FAD and its effect on disulfide bond formation was investigated in rat liver microsomal vesicles. By measuring the intravesicular FAD-accessible space, we observed that FAD permeates across the microsomal membrane and accumulates in the lumen. Rapid filtration experiments also demonstrated the uptake and efflux of the compound, which could be inhibited by atractyloside and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. FAD entering the lumen promoted the oxidation of protein thiols and increased the intraluminal oxidation of glucose-6-phosphate. These findings support the notion that, similar to yeast, free FAD may have a decisive role in the mechanism of oxidative protein folding in the endoplasmic reticulum lumen of mammalian cells.
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Affiliation(s)
- Marianne Varsányi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, 1444 Budapest, Hungary
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Guionie O, Clottes E, Stafford K, Burchell A. Identification and characterisation of a new human glucose-6-phosphatase isoform. FEBS Lett 2003; 551:159-64. [PMID: 12965222 DOI: 10.1016/s0014-5793(03)00903-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The liver endoplasmic reticulum glucose-6-phosphatase catalytic subunit (G6PC1) catalyses glucose 6-phosphate hydrolysis during gluconeogenesis and glycogenolysis. The highest glucose-6-phosphatase activities are found in the liver and the kidney; there have been many reports of glucose 6-phosphate hydrolysis in other tissues. We cloned a new G6Pase isoform (G6PC3) from human brain encoded by a six-exon gene (chromosome 17q21). G6PC3 protein was able to hydrolyse glucose 6-phosphate in transfected Chinese hamster ovary cells. The optimal pH for glucose 6-phosphate hydrolysis was lower and the K(m) higher relative to G6PC1. G6PC3 preferentially hydrolyzed other substrates including pNPP and 2-deoxy-glucose-6-phosphate compared to the liver enzyme.
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Affiliation(s)
- Olivier Guionie
- Ninewells Hospital and Medical School, University of Dundee, DD1 9SY Dundee, UK
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50
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Carreras FI, Gradilone SA, Mazzone A, García F, Huang BQ, Ochoa JE, Tietz PS, Larusso NF, Calamita G, Marinelli RA. Rat hepatocyte aquaporin-8 water channels are down-regulated in extrahepatic cholestasis. Hepatology 2003; 37:1026-33. [PMID: 12717383 DOI: 10.1053/jhep.2003.50170] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hepatocytes express the water channel aquaporin-8 (AQP8), which is mainly localized in intracellular vesicles, and its adenosine 3',5'-cyclic monophosphate (cAMP)-induced translocation to the plasma membrane facilitates osmotic water movement during canalicular bile secretion. Thus, defective expression of AQP8 may be associated with secretory dysfunction of hepatocytes caused by extrahepatic cholestasis. We studied the effect of 1, 3, and 7 days of bile duct ligation (BDL) on protein expression, subcellular localization, and messenger RNA (mRNA) levels of AQP8; this was determined in rat livers by immunoblotting in subcellular membranes, light immunohistochemistry, immunogold electron microscopy, and Northern blotting. One day of BDL did not affect expression or subcellular localization of AQP8. Three days of BDL reduced the amount of intracellular AQP8 (75%; P <.001) without affecting its plasma membrane expression. Seven days after BDL, AQP8 was markedly decreased in intracellular (67%; P <.05) and plasma (56%; P <.05) membranes. Dibutyryl cAMP failed to increase AQP8 in plasma membranes from liver slices, suggesting a defective translocation of AQP8 in 7-day BDL rats. Immunohistochemistry and immunoelectron microscopy in liver sections confirmed the BDL-induced decreased expression of hepatocyte AQP8 in intracellular vesicles and canalicular membranes. AQP8 mRNA expression was unaffected by 1-day BDL but was significantly increased by about 200% in 3- and 7-day BDL rats, indicating a posttranscriptional mechanism for protein level reduction. In conclusion, BDL-induced extrahepatic cholestasis caused posttranscriptional down-regulation of hepatocyte AQP8 protein expression. Defective expression of AQP8 water channels may contribute to bile secretory dysfunction of cholestatic hepatocytes.
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Affiliation(s)
- Flavia I Carreras
- Instituto de Fisiología Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Santa Fe, Argentina
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