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Garcia-Irigoyen O, Bovenga F, Piglionica M, Piccinin E, Cariello M, Arconzo M, Peres C, Corsetto PA, Rizzo AM, Ballanti M, Menghini R, Mingrone G, Lefebvre P, Staels B, Shirasawa T, Sabbà C, Villani G, Federici M, Moschetta A. Enterocyte superoxide dismutase 2 deletion drives obesity. iScience 2022; 25:103707. [PMID: 35036884 PMCID: PMC8753186 DOI: 10.1016/j.isci.2021.103707] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 10/19/2021] [Accepted: 12/23/2021] [Indexed: 02/07/2023] Open
Abstract
Compelling evidence support an involvement of oxidative stress and intestinal inflammation as early events in the predisposition and development of obesity and its related comorbidities. Here, we show that deficiency of the major mitochondrial antioxidant enzyme superoxide dismutase 2 (SOD2) in the gastrointestinal tract drives spontaneous obesity. Intestinal epithelium-specific Sod2 ablation in mice induced adiposity and inflammation via phospholipase A2 (PLA2) activation and increased release of omega-6 polyunsaturated fatty acid arachidonic acid. Remarkably, this obese phenotype was rescued when fed an essential fatty acid-deficient diet, which abrogates de novo biosynthesis of arachidonic acid. Data from clinical samples revealed that the negative correlation between intestinal Sod2 mRNA levels and obesity features appears to be conserved between mice and humans. Collectively, our findings suggest a role of intestinal Sod2 levels, PLA2 activity, and arachidonic acid in obesity presenting new potential targets of therapeutic interest in the context of this metabolic disorder.
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Affiliation(s)
- Oihane Garcia-Irigoyen
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Fabiola Bovenga
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Marilidia Piglionica
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Elena Piccinin
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.,Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Marica Cariello
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Maria Arconzo
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Claudia Peres
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Paola Antonia Corsetto
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via D. Trentacoste 2, 20133 Milan, Italy
| | - Angela Maria Rizzo
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via D. Trentacoste 2, 20133 Milan, Italy
| | - Marta Ballanti
- Center for Atherosclerosis, Policlinico Tor Vergata, 00133 Rome, Italy
| | - Rossella Menghini
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Geltrude Mingrone
- Department of Internal Medicine, Catholic University, Rome, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Diabetes and Nutritional Sciences, Hodgkin Building, Guy's Campus, King's College London, London, UK
| | - Philippe Lefebvre
- Université Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011-EGID, F-59000 Lille, France
| | - Bart Staels
- Université Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011-EGID, F-59000 Lille, France
| | - Takuji Shirasawa
- Department of Molecular Gerontology, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan
| | - Carlo Sabbà
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Gaetano Villani
- Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Massimo Federici
- Center for Atherosclerosis, Policlinico Tor Vergata, 00133 Rome, Italy.,Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Antonio Moschetta
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.,IRCCS Istituto Tumori "Giovanni Paolo II", Viale O. Flacco 65, 70124 Bari, Italy
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Hernández MC, Rojas P, Carrasco F, Basfi-Fer K, Valenzuela R, Codoceo J, Inostroza J, Ruz M. Fatty acid desaturation in red blood cell membranes of patients with type 2 diabetes is improved by zinc supplementation. J Trace Elem Med Biol 2020; 62:126571. [PMID: 32534376 DOI: 10.1016/j.jtemb.2020.126571] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/14/2020] [Accepted: 05/26/2020] [Indexed: 12/26/2022]
Abstract
BACKGROUND/OBJECTIVE Membrane flexibility can be a determining factor in pathophysiological mechanisms of type 2 diabetes (T2D). As a cofactor of delta-5 desaturase (D5D) and delta-6 desaturase (D6D), and gene expression regulator, zinc may play a role modulating membrane flexibility by increasing membrane polyunsaturated fatty acids (PUFA) abundance. The objective of this study was to evaluate the effect of a 24-month zinc supplementation (30 mg elemental zinc) on membrane fatty acid composition in patients with T2D. SUBJECTS/METHODS Sixty patients with T2D were evaluated. Thirty were randomly assigned to the zinc supplemented group and thirty to the placebo group. Fatty acid composition in red blood cell (RBC) membranes was determined by gas chromatography. Expression of gene encoding for D5D (FADS1), and D6D (FADS2) were evaluated in peripheral blood mononuclear cells by real-time polymerase chain reaction. RESULTS After 24 months of supplementation, a greater abundance of docosapentaenoic acid (C22:5 n-3), arachidonic acid (C20:4 n-6), adrenic acid (C22:4 n-6), and total n-6 PUFA was found (p = 0.001, p = 0.007, p = 0.033, p = 0.048, respectively). The unsaturated fatty acids/saturated fatty acids ratio, and unsaturation index was increased in the zinc supplemented group at month 24 (p = 0.003 and p = 0.000, respectively). FADS1 gene was upregulated in the zinc group in relation to placebo at month 12 (p = 0.020). CONCLUSIONS Supplementation with 30 mg/d elemental zinc during 24 months in patients with T2D had an effect on the composition of RBC membranes increasing PUFA abundance and in turn, improving membrane flexibility. This effect may be mediated by induction of D5D gene expression.
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Affiliation(s)
| | - Pamela Rojas
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Fernando Carrasco
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Karen Basfi-Fer
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Rodrigo Valenzuela
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Juana Codoceo
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Jorge Inostroza
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Manuel Ruz
- From the Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile.
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Arzouni AA, Vargas-Seymour A, Dhadda PK, Rackham CL, Huang GC, Choudhary P, King AJF, Jones PM. Characterization of the Effects of Mesenchymal Stromal Cells on Mouse and Human Islet Function. Stem Cells Transl Med 2019; 8:935-944. [PMID: 31066521 PMCID: PMC6708063 DOI: 10.1002/sctm.19-0023] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/13/2019] [Indexed: 12/19/2022] Open
Abstract
Islet transplantation has the potential to cure type 1 diabetes, but current transplantation protocols are not optimal and there is extensive loss of islet β‐cell insulin secretory function during the immediate post‐transplantation period. Studies using experimental models of diabetes have shown that the coculture of islets with mesenchymal stromal cells (MSCs) prior to transplantation improves graft function, but several variables differed among research groups (e.g., type of MSCs used and the treatment conditions). We have therefore assessed the effects of MSCs on mouse and human islets by investigating the importance of tissue source for MSCs, the coculture protocol configuration and length, the effect of activated MSCs, and different β‐cell secretory stimuli. MSCs derived from adipose tissue (aMSCs) were the most effective at supporting β‐cell insulin secretion in both mouse and human islets, in a direct contact coculture configuration. Preculture with aMSCs enhanced both phases of glucose‐induced insulin secretion and further enhanced secretory responses to the non‐nutrients carbachol and arginine. These effects required a coculture period of 48–72 hours and were not dependent on activation of the MSCs. Thus, direct contact coculture with autologous, adipose‐derived MSCs for a minimum of 48 hours before implantation is likely to be an effective addition to human islet transplantation protocols. stem cells translational medicine2019;8:935&944
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Affiliation(s)
- Ahmed A Arzouni
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Andreia Vargas-Seymour
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Paramjeet K Dhadda
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Chloe L Rackham
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Guo-Cai Huang
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Pratik Choudhary
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Aileen J F King
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
| | - Peter M Jones
- Department of Diabetes, School of Life Course Sciences, King's College London, London, United Kingdom
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Fatty acid consumption and incident type 2 diabetes: an 18-year follow-up in the female E3N (Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale) prospective cohort study. Br J Nutr 2016; 116:1807-1815. [DOI: 10.1017/s0007114516003883] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
AbstractWe evaluated the association between dietary estimates of fatty acid (FA) consumption and type 2 diabetes (T2D) risk in the French E3N (Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale) cohort. In total, 71 334 women without diabetes at baseline were followed up from 1993 to 2011. Diabetes was identified using questionnaires and drug-reimbursement claims, and incident cases were validated. FA consumption in 1993 was estimated from a validated dietary questionnaire. Cox regression estimated hazard ratios (HR) and 95 % CI of diabetes risk, comparing the upper tertile group with the lowest. High n-3 PUFA consumption was associated with T2D even after adjustment for confounders, including other FA and BMI (HR 1·26; 95 % CI 1·13, 1·41; upper tertile compared with lowest). Upon stratification by overweight (BMI≥25 kg/m2)/non-overweight, a positive association between total PUFA consumption and T2D was observed, but it was restricted to non-overweight women (HR 1·22; 95 % CI 1·05, 1·42), whereas n-3 PUFA consumption was associated with increased T2D risk in both BMI strata (BMI<25 kg/m2: HR 1·19; 95 % CI 1·01, 1·40 and BMI≥25 kg/m2: HR 1·38; 95 % CI 1·20, 1·59). Within the n-3 PUFA, high DPA (HR 1·41; 95 % CI 1·23, 1·63) and α-linolenic acid (ALA) intakes were associated with increased T2D risk, but the effects of ALA were restricted to overweight women (HR 1·17; 95 % CI 1·01, 1·36). Within the n-6 PUFA, only arachidonic acid (AA) intake was associated with T2D risk (HR 1·49; 95 % CI 1·33, 1·66). The associations with DPA and AA persisted even after adjustment of their principal source in this cohort, the consumption of meat. The effects of PUFA are heterogeneous within the FA group. Intake of DPA and AA may contribute to T2D development.
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Karakas SE, Perroud B, Kind T, Palazoglu M, Fiehn O. Changes in plasma metabolites and glucose homeostasis during omega-3 polyunsaturated fatty acid supplementation in women with polycystic ovary syndrome. BBA CLINICAL 2016; 5:179-85. [PMID: 27182493 PMCID: PMC4857160 DOI: 10.1016/j.bbacli.2016.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/04/2016] [Accepted: 04/11/2016] [Indexed: 01/22/2023]
Abstract
Background Both fish (FO) and flaxseed oils (FLX) are n-3 polyunsaturated fatty acids (PUFA). Fish oil contains long chain while FLX contains essential n-3 PUFA. We demonstrated that FO altered insulin secretion and resistance in polycystic ovary syndrome (PCOS) women but FLX did not. Surprisingly, the effects of FO were similar to those of the n-6 PUFA-rich soybean oil (SBO). Since increased branched chain (BCAA) and aromatic amino acids (AA) affect insulin secretion and resistance, we investigated whether FO, FLX and /or SBO affect plasma metabolites, especially AA. Methods and findings In this six-week, randomized, 3-parallel arm, double-blinded study, 54 women received 3.5 g/day FO, FLX or SBO. In 51 completers (17 from each arm), fasting plasma metabolites were measured at the beginning and at the end. As compared to FLX, FO and SBO increased insulin response and resistance as well as several BCAA and aromatic AA. Pathway analysis indicated that FO exerted the largest biochemical impact, affecting AA degradation and biosynthesis, amine, polyamine degradation and alanine, glycine, l-carnitine biosynthesis and TCA cycle, while FLX had minimal impact affecting only alanine biosynthesis and l-cysteine degradation. Conclusion Effects of FO and SBO on plasma AA were similar and differed significantly from those of the FLX. The primary target of dietary PUFA is not known. Dietary PUFA may influence insulin secretion and resistance directly and alter plasma AA indirectly. Alternatively, as a novel concept, dietary PUFA may directly affect AA metabolism and the changes in insulin secretion and resistance may be secondary. Increased serum branched chain amino acids (BCAA) and aromatic amino acids are associated with insulin resistance and type 2 diabetes. Although both fish oil (FO) and flaxseed oil (FLX) are n-3 PUFA, FO contains the long chain, while FLX contains the essential n-3 PUFA. We compared the effects of different PUFAs on plasma metabolites in women with insulin resistance. Fish oil, but not FLX, increased plasma BCAA, and insulin resistance and secretion, indicating differential effects of essential vs. long chain n-3 PUFA. It is possible that effects of FO on insulin resistance and secretion may have been indirect, through its actions on BCAA metabolism.
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Affiliation(s)
- Sidika E Karakas
- The University of California at Davis, Department of Internal Medicine, Division of Endocrinology, Clinical Nutrition and Vascular Medicine, Davis, CA, United States; Department of Veterans Affairs Northern California Health Care System, Mather, CA, United States
| | - Bertrand Perroud
- University of California at Davis Genome Center, Davis, CA, United States
| | - Tobias Kind
- University of California at Davis Genome Center, Davis, CA, United States
| | - Mine Palazoglu
- University of California at Davis Genome Center, Davis, CA, United States
| | - Oliver Fiehn
- University of California at Davis Genome Center, Davis, CA, United States
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Al-Romaiyan A, Liu B, Docherty R, Huang GC, Amiel S, Persaud SJ, Jones PM. Investigation of intracellular signalling cascades mediating stimulatory effect of a Gymnema sylvestre extract on insulin secretion from isolated mouse and human islets of Langerhans. Diabetes Obes Metab 2012; 14:1104-13. [PMID: 22775778 DOI: 10.1111/j.1463-1326.2012.01660.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 05/27/2012] [Accepted: 07/02/2012] [Indexed: 01/02/2023]
Abstract
AIM Traditional plant-based remedies such as Gymnema sylvestre (GS) extracts have been used to treat diabetes mellitus for many centuries. We have shown previously that a novel GS extract, OSA®, has a direct effect on insulin secretion but its mode of action has not been studied in detail Thus this study investigated the possible underlying mechanism(s) by which OSA® exerts its action. METHODS The effects of OSA® on [Ca(2+)]i and K(+) conductances were assessed by Ca(2+) microfluorimetry and electrophysiology in dispersed mouse islets and MIN6 β-cells, respectively. Isolated mouse (from 20 to 25 mice) and human (from 3 donors) islets, and MIN6 β-cells, were used to investigate whether the stimulatory effect of OSA® on insulin secretion was dependent on the presence of extracellular calcium and protein kinase activation. RESULTS OSA ®-induced insulin secretion from mouse islets and MIN6 β-cells was inhibited by nifedipine, a voltage-gated Ca(2+) channel blocker, and by the removal of extracellular Ca(2+), respectively. OSA® did not affect the activities of KATP channels or voltage-dependent K(+) channels in MIN6 β-cells but it caused an increase in intracellular Ca(2+) ([Ca(2+)]i) concentrations in Fura-2-loaded mouse islet cells. The insulin secretagogue effect of OSA® was dependent, in part, on protein kinase activation since incubating mouse or human islets with staurosporine, a general protein kinase inhibitor, resulted in partial inhibition of OSA®-induced insulin secretion. Experiments using permeabilized, Ca(2+)-clamped MIN6 β-cells revealed a Ca(2+)-independent component action of OSA® at a late stage in the stimulus-response coupling pathway. OSA®-induced insulin secretion was unexpectedly associated with a decrease in intracellular cAMP levels. CONCLUSIONS These data indicate that the GS isolate OSA® stimulates insulin secretion from mouse and human islets in vitro, at least in part as a consequence of Ca(2+) influx and protein kinase activation.
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Affiliation(s)
- A Al-Romaiyan
- Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College London, London, UK
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Kowluru A. Differential regulation by fatty acids of protein histidine phosphorylation in rat pancreatic islets. Mol Cell Biochem 2005; 266:175-82. [PMID: 15646040 DOI: 10.1023/b:mcbi.0000049157.03855.74] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Long-chain fatty acids (e.g. arachidonic acid) have been implicated in physiological control of insulin secretion. We previously reported histidine phosphorylation of at least two islet proteins (e.g., NDP kinase and the beta subunit of trimeric G-proteins), and suggested that such a signalling step may have regulatory roles in beta cell signal transduction, specifically at the level of G-protein activation. Since our earlier findings also indicated potential regulation by long-chain fatty acids of islet G-proteins, we undertook the current study to verify putative regulation, by fatty acids, of protein histidine phosphorylation of NDP kinase and Gbeta subunit in normal rat islets. The phosphoenzyme formation of NDP kinase was stimulated by various fatty acids in the following rank order: linoleic acid > arachidonic acid > oleic acid > palmitic acid = stearic acid = control. Furthermore, the catalytic activity of NDP kinase was stimulated by these fatty acids in the rank order of: oleic acid > arachidonic acid > linoleic acid > palmitic acid = stearic acid = control. Arachidonic acid methyl ester, an inactive analog of arachidonic acid, did not significantly affect either the phosphoenzyme formation or the catalytic activity of NDP kinase. Interestingly, arachidonic acid exerted dual effects on the histidine phosphorylation of beta subunit; it significantly stimulated the phosphorylation at 33 microM beyond which it was inhibitory. Together, these findings identify additional loci (e.g., NDP kinase and Gbeta subunit) at which unsaturated, but not saturated, fatty acids could exert their intracellular effects leading to exocytotic secretion of insulin.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Wayne State University and beta Cell Biochemistry Laboratory, John D Dingell VA Medical Center, Detroit, MI 48202, USA.
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Song K, Zhang X, Zhao C, Ang NT, Ma ZA. Inhibition of Ca2+-independent phospholipase A2 results in insufficient insulin secretion and impaired glucose tolerance. Mol Endocrinol 2004; 19:504-15. [PMID: 15471944 PMCID: PMC2917620 DOI: 10.1210/me.2004-0169] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Islet Ca2+-independent phospholipase A2 (iPLA2) is postulated to mediate insulin secretion by releasing arachidonic acid in response to insulin secretagogues. However, the significance of iPLA2 signaling in insulin secretion in vivo remains unexplored. Here we investigated the physiological role of iPLA2 in beta-cell lines, isolated islets, and mice. We showed that small interfering RNA-specific silencing of iPLA2 expression in INS-1 cells significantly reduced insulin-secretory responses of INS-1 cells to glucose. Immunohistochemical analysis revealed that mouse islet cells expressed significantly higher levels of iPLA2 than pancreatic exocrine acinar cells. Bromoenol lactone (BEL), a selective inhibitor of iPLA2, inhibited glucose-stimulated insulin secretion from isolated mouse islets; this inhibition was overcome by exogenous arachidonic acid. We also showed that iv BEL administration to mice resulted in sustained hyperglycemia and reduced insulin levels during glucose tolerance tests. Clamp experiments demonstrated that the impaired glucose tolerance was due to insufficient insulin secretion rather than decreased insulin sensitivity. Short-term administration of BEL to mice had no effect on fasting glucose levels and caused no apparent pathological changes of islets in pancreas sections. These results unambiguously demonstrate that iPLA2 signaling plays an important role in glucose-stimulated insulin secretion under physiological conditions.
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Affiliation(s)
- Keying Song
- Division of Experimental Diabetes and Aging, Department of Geriatrics and Adult Development, Mount Sinai School of Medicine, New York, New York 10029, USA
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Jones PM, Burns CJ, Belin VD, Roderigo-Milne HM, Persaud SJ. The role of cytosolic phospholipase A(2) in insulin secretion. Diabetes 2004; 53 Suppl 1:S172-8. [PMID: 14749284 DOI: 10.2337/diabetes.53.2007.s172] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cytosolic phospholipase A(2) (cPLA(2)) comprises a widely expressed family of enzymes, some members of which have the properties required of signal transduction elements in electrically excitable cells. Thus, alpha- and beta-isoforms of cPLA(2) are activated by the increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) achieved in depolarized cells. Activation is associated with a redistribution of the enzyme within the cell; activation of cPLA(2) generates arachidonic acid (AA), a biologically active unsaturated fatty acid that can be further metabolized to generate a plethora of biologically active molecules. Studies using relatively nonselective pharmacological inhibitors have implicated cPLA(2) in insulin secretory responses to stimuli that elevate beta-cell [Ca(2+)](i); therefore, we have investigated the role of cPLA(2) in beta-cell function by generating beta-cell lines that under- or overexpress the alpha-isoform of cPLA(2). The functional phenotype of the modified cells was assessed by observation of cellular ultrastructure, by measuring insulin gene expression and insulin protein content, and by measuring the effects of insulin secretagogues on cPLA(2) distribution, on changes in [Ca(2+)](i), and on the rate and pattern of insulin secretion. Our results suggest that cPLA(2) is not required for the initiation of insulin secretion from beta-cells, but that it plays an important role in the maintenance of beta-cell insulin stores. Our data also demonstrate that excessive production of, or exposure to, AA is deleterious to normal beta-cell secretory function through metabolic dysfunction.
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Affiliation(s)
- Peter M Jones
- Centre for Reproduction, Endocrinology and Diabetes, GKT School of Biomedical Sciences, King's College London, London, UK.
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Dunne MJ, Ämmälä C, Straub SG, Sharp GWG. Electrophysiology of the β Cell and Mechanisms of Inhibition of Insulin Release. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Gilon P, Henquin JC. Mechanisms and physiological significance of the cholinergic control of pancreatic beta-cell function. Endocr Rev 2001; 22:565-604. [PMID: 11588141 DOI: 10.1210/edrv.22.5.0440] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acetylcholine (ACh), the major parasympathetic neurotransmitter, is released by intrapancreatic nerve endings during the preabsorptive and absorptive phases of feeding. In beta-cells, ACh binds to muscarinic M(3) receptors and exerts complex effects, which culminate in an increase of glucose (nutrient)-induced insulin secretion. Activation of PLC generates diacylglycerol. Activation of PLA(2) produces arachidonic acid and lysophosphatidylcholine. These phospholipid-derived messengers, particularly diacylglycerol, activate PKC, thereby increasing the efficiency of free cytosolic Ca(2+) concentration ([Ca(2+)](c)) on exocytosis of insulin granules. IP3, also produced by PLC, causes a rapid elevation of [Ca(2+)](c) by mobilizing Ca(2+) from the endoplasmic reticulum; the resulting fall in Ca(2+) in the organelle produces a small capacitative Ca(2+) entry. ACh also depolarizes the plasma membrane of beta-cells by a Na(+)- dependent mechanism. When the plasma membrane is already depolarized by secretagogues such as glucose, this additional depolarization induces a sustained increase in [Ca(2+)](c). Surprisingly, ACh can also inhibit voltage-dependent Ca(2+) channels and stimulate Ca(2+) efflux when [Ca(2+)](c) is elevated. However, under physiological conditions, the net effect of ACh on [Ca(2+)](c) is always positive. The insulinotropic effect of ACh results from two mechanisms: one involves a rise in [Ca(2+)](c) and the other involves a marked, PKC-mediated increase in the efficiency of Ca(2+) on exocytosis. The paper also discusses the mechanisms explaining the glucose dependence of the effects of ACh on insulin release.
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Affiliation(s)
- P Gilon
- Unité d'Endocrinologie et Métabolisme, University of Louvain Faculty of Medicine, B-1200 Brussels, Belgium.
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Garcia JR, Curi R, Martins EF, Carpinelli AR. Macrophages transfer [14C]-labelled fatty acids to pancreatic islets in culture. Cell Biochem Funct 2001; 19:11-7. [PMID: 11223866 DOI: 10.1002/cbf.887] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Macrophages are able to produce, export, and transfer fatty acids to lymphocytes in culture. The purpose of this study was to examine if labelled fatty acids could be transferred from macrophages to pancreatic islets in co-culture. We found that after 3 h of co-culture the transfer of fatty acids to pancreatic islets was: arachidonic >> oleic > linoleic = palmitic. Substantial amounts of the transferred fatty acids were found in the phospholipid fraction; 87.6% for arachidonic, 59.9% for oleic, 53.1% for palmitic, and 36.9% for linoleic acids. The remaining radioactivity was distributed among the other lipid fractions analysed (namely polar lipids, cholesterol, fatty acids, triacylglycerol and cholesterol ester), varying with the fatty acid used. For linoleic acid, a significant proportion (63.1%) was almost equally distributed in these lipid fractions. Also, it was observed that transfer of fatty acids from macrophages to pancreatic islets is time-dependent up to 24 h, being constant and linear with time for palmitic acid and remaining constant after 12 h for oleic acid. These results lead us to postulate that in addition to the serum, circulating monocytes may also be a source of fatty acids to pancreatic islets, mainly arachidonic acid.
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Affiliation(s)
- J R Garcia
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, Sao Paulo, SP, Brazil
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13
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Fujimoto S, Tsuura Y, Ishida H, Tsuji K, Mukai E, Kajikawa M, Hamamoto Y, Takeda T, Yamada Y, Seino Y. Augmentation of basal insulin release from rat islets by preexposure to a high concentration of glucose. Am J Physiol Endocrinol Metab 2000; 279:E927-40. [PMID: 11001778 DOI: 10.1152/ajpendo.2000.279.4.e927] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have found that preexposure to an elevated concentration of glucose reversibly induces an enhancement of basal insulin release from rat pancreatic islets dependent on glucose metabolism. This basal insulin release augmented by priming was not suppressed by reduction of the intracellular ATP or Ca(2+) concentration, because even in the absence of ATP at low Ca(2+), the augmentation was not abolished from primed electrically permeabilized islets. Moreover, it was not inhibited by an alpha-adrenergic antagonist, clonidine. A threshold level of GTP is required to induce these effects, because together with adenine, mycophenolic acid, a cytosolic GTP synthesis inhibitor, completely abolished the enhancement of basal insulin release due to the glucose-induced priming without affecting the glucose-induced increment in ATP content and ATP-to-ADP ratio. In addition, a GDP analog significantly suppressed the enhanced insulin release due to priming from permeabilized islets in the absence of ATP at low Ca(2+), suggesting that the GTP-sensitive site may play a role in the augmentation of basal insulin release due to the glucose-induced priming effect.
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Affiliation(s)
- S Fujimoto
- Department of Metabolism and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606 - 8507, Japan.
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14
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Jones PM, Persaud SJ. Protein kinases, protein phosphorylation, and the regulation of insulin secretion from pancreatic beta-cells. Endocr Rev 1998; 19:429-61. [PMID: 9715374 DOI: 10.1210/edrv.19.4.0339] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- P M Jones
- Biomedical Sciences Division, King's College London, United Kingdom.
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15
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Abstract
Several agonists including norepinephrine, somatostatin, galanin, and prostaglandins inhibit insulin release. The inhibition is sensitive to pertussis toxin, indicating the involvement of heterotrimeric Gi and/or Go proteins. Receptors for the different agonists have different selectivity for these G proteins. After G protein activation, the alpha- and beta gamma-subunits dissociate and interact with multiple targets to inhibit release. These include 1) the ATP-sensitive K+ channel and perhaps other K+ channels, 2) L-type voltage-dependent Ca2+ channels, 3) adenylyl cyclase, and 4) a "distal" site late in stimulus-secretion coupling. The latter effect, which may be exerted close to the final stage of exocytosis, is the most powerful of the individual inhibitory mechanisms. G protein action on the target molecules is determined by the individual G proteins activated and their specificity for the targets. The L-type Ca2+ channel is inhibited by G(o)-1. Adenylyl cyclase is inhibited by Gi-2 and Gi-3. The distal inhibition can be exerted by Gi-1, Gi-2, Gi-3, and G(o)-2. Thus there is both selectivity and promiscuity in G protein action in the beta-cell. These characteristics allow an inhibitory ligand to be effective at multiple targets and to act differentially from other inhibitory ligands.
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Affiliation(s)
- G W Sharp
- Department of Pharmacology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
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16
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17
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Abstract
We have previously identified expression of multiple protein kinase C (PKC) isoforms in insulinoma-derived beta-cells and whole islets. Both PKC delta and PKC alpha appear to be the more abundantly expressed isoforms. In this report we studied the effects of arachidonic acid (AA) on the subcellular distribution of PKC alpha and PKC delta. AA has been reported to activate both PKC alpha and PKC delta and it is thought to be an important second messenger in beta-cells. Here we report that AA interacted with and altered beta-cell pools of PKC delta preferentially over PKC alpha. AA (100 microM) over the course of 45 min reduced cytosolic levels of PKC delta (to 40 +/- 15%, compared to time zero control) leaving membrane- and cytoskeleton-associated levels near control levels. Analysis of whole cell homogenates showed a slight down-regulation of PKC delta indicating proteolysis. The down-regulation of cytosolic PKC delta appeared to be isoform specific since cytosolic PKC alpha remained at control levels over the time course. The response was dose-dependent and negligible at concentrations below 30 microM and occurred, at least partially, in the cytosolic compartment of the cell. Indomethacin also down-regulated cytosolic PKC delta preferentially over PKC alpha possibly through accumulation of AA. These findings suggest that cytosolic PKC delta may be a downstream target of this beta-cell second messenger.
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Affiliation(s)
- K L Knutson
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA
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18
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Emmerling MR, Dudley DT, Dyer RD, Carroll RT, Doyle PD, Davis RE. The role of arachidonic acid in the secretion of the amyloid precursor protein (APP). Ann N Y Acad Sci 1996; 777:310-5. [PMID: 8624105 DOI: 10.1111/j.1749-6632.1996.tb34438.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have studied the activation of human ml-muscarinic receptors in a genetically engineered Chinese hamster ovary cell line (CHO-ml) to determine which second messenger systems affect the secretion of APP via the non-amyloidogenic route. Carbachol activation of the signaling pathways in CHO-ml cells promotes APP secretion by activation of both protein kinase C (PKC)-dependent or Ca(++)-dependent second messenger pathways. Both pathways converge to increase the enzyme activity of phospholipase A2 (PLA2), the enzyme that releases arachidonic acid from cellular stores. Directly activating PLA2 with melittin, a peptide from bee venom, or by adding arachidonic acid directly to cultured cells increases the secretion of APP. Thus, our results indicate that arachidonic acid is yet another cellular second messenger involved in regulating the metabolism of APP in addition to PKC and cytoplasmic Ca++. Moreover, activation of PLA2 appears to be an obligatory event in increasing the secretion of APP from CHO-ml cells by the various methods of activation that we have tried thus far.
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Affiliation(s)
- M R Emmerling
- Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Co., Ann Arbor, Michigan 48106, USA.
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19
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Cell Surface Receptor Mediated Control of Amyloid Precursor Protein Secretion: Involvement of Pleiotropic Signal Transduction Cascades. ACTA ACUST UNITED AC 1995. [DOI: 10.1007/978-1-4757-9145-7_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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20
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Abstract
This review summarises briefly studies performed in the last 5-6 years concerning the role of second messengers in the regulation of insulin secretion, using intact and electrically permeabilized rat islets of Langerhans. It is concluded that cyclic AMP (through protein kinase A), calcium (through calcium-calmodulin dependent protein kinases) and diacylglycerol (through protein kinase C) may be important second messengers in modulating the effects of specific secretagogues on insulin release. However, recent studies strongly suggest that neither protein kinase A nor protein kinase C are directly involved in the regulation of insulin secretion by glucose. The possible involvement of other second messengers, nitric oxide and arachidonic acid, in the regulation of secretion is also briefly reviewed.
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Affiliation(s)
- S L Howell
- Biomedical Sciences Division, King's College London, UK
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