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Jeyarajan S, Zhang IX, Arvan P, Lentz SI, Satin LS. Simultaneous Measurement of Changes in Mitochondrial and Endoplasmic Reticulum Free Calcium in Pancreatic Beta Cells. BIOSENSORS 2023; 13:382. [PMID: 36979594 PMCID: PMC10046164 DOI: 10.3390/bios13030382] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/28/2023] [Accepted: 03/08/2023] [Indexed: 05/28/2023]
Abstract
The free calcium (Ca2+) levels in pancreatic beta cell organelles have been the subject of many recent investigations. Under pathophysiological conditions, disturbances in these pools have been linked to altered intracellular communication and cellular dysfunction. To facilitate studies of subcellular Ca2+ signaling in beta cells and, particularly, signaling between the endoplasmic reticulum (ER) and mitochondria, we designed a novel dual Ca2+ sensor which we termed DS-1. DS-1 encodes two stoichiometrically fluorescent proteins within a single plasmid, G-CEPIA-er, targeted to the ER and R-CEPIA3-mt, targeted to mitochondria. Our goal was to simultaneously measure the ER and mitochondrial Ca2+ in cells in real time. The Kds of G-CEPIA-er and R-CEPIA3-mt for Ca2+ are 672 and 3.7 μM, respectively. Confocal imaging of insulin-secreting INS-1 832/13 expressing DS-1 confirmed that the green and red fluorophores correctly colocalized with organelle-specific fluorescent markers as predicted. Further, we tested whether DS-1 exhibited the functional properties expected by challenging an INS-1 cell to glucose concentrations or drugs having well-documented effects on the ER and mitochondrial Ca2+ handling. The data obtained were consistent with those seen using other single organelle targeted probes. These results taken together suggest that DS-1 is a promising new approach for investigating Ca2+ signaling within multiple organelles of the cell.
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Affiliation(s)
- Sivakumar Jeyarajan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; (S.J.)
| | - Irina X Zhang
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; (S.J.)
| | - Peter Arvan
- Department of Internal Medicine, Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105, USA
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Stephen I. Lentz
- Department of Internal Medicine, Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Leslie S. Satin
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; (S.J.)
- Department of Internal Medicine, Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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2
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Stacpoole PW, McCall CE. The pyruvate dehydrogenase complex: Life's essential, vulnerable and druggable energy homeostat. Mitochondrion 2023; 70:59-102. [PMID: 36863425 DOI: 10.1016/j.mito.2023.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/30/2023] [Accepted: 02/13/2023] [Indexed: 03/04/2023]
Abstract
Found in all organisms, pyruvate dehydrogenase complexes (PDC) are the keystones of prokaryotic and eukaryotic energy metabolism. In eukaryotic organisms these multi-component megacomplexes provide a crucial mechanistic link between cytoplasmic glycolysis and the mitochondrial tricarboxylic acid (TCA) cycle. As a consequence, PDCs also influence the metabolism of branched chain amino acids, lipids and, ultimately, oxidative phosphorylation (OXPHOS). PDC activity is an essential determinant of the metabolic and bioenergetic flexibility of metazoan organisms in adapting to changes in development, nutrient availability and various stresses that challenge maintenance of homeostasis. This canonical role of the PDC has been extensively probed over the past decades by multidisciplinary investigations into its causal association with diverse physiological and pathological conditions, the latter making the PDC an increasingly viable therapeutic target. Here we review the biology of the remarkable PDC and its emerging importance in the pathobiology and treatment of diverse congenital and acquired disorders of metabolic integration.
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Affiliation(s)
- Peter W Stacpoole
- Department of Medicine (Division of Endocrinology, Metabolism and Diabetes), and Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL, United States.
| | - Charles E McCall
- Department of Internal Medicine and Translational Sciences, and Department of Microbiology and Immunology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
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3
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Yang ML, Kibbey RG, Mamula MJ. Biomarkers of autoimmunity and beta cell metabolism in type 1 diabetes. Front Immunol 2022; 13:1028130. [PMID: 36389721 PMCID: PMC9647083 DOI: 10.3389/fimmu.2022.1028130] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/13/2022] [Indexed: 09/10/2023] Open
Abstract
Posttranslational protein modifications (PTMs) are an inherent response to physiological changes causing altered protein structure and potentially modulating important biological functions of the modified protein. Besides cellular metabolic pathways that may be dictated by PTMs, the subtle change of proteins also may provoke immune attack in numerous autoimmune diseases. Type 1 diabetes (T1D) is a chronic autoimmune disease destroying insulin-producing beta cells within the pancreatic islets, a result of tissue inflammation to specific autoantigens. This review summarizes how PTMs arise and the potential pathological consequence of PTMs, with particular focus on specific autoimmunity to pancreatic beta cells and cellular metabolic dysfunction in T1D. Moreover, we review PTM-associated biomarkers in the prediction, diagnosis and in monitoring disease activity in T1D. Finally, we will discuss potential preventive and therapeutic approaches of targeting PTMs in repairing or restoring normal metabolic pathways in pancreatic islets.
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Affiliation(s)
- Mei-Ling Yang
- Section of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Yale University, New Haven, CT, United States
| | - Richard G. Kibbey
- Section of Endocrinology, Department of Internal Medicine, Yale University, New Haven, CT, United States
| | - Mark J. Mamula
- Section of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Yale University, New Haven, CT, United States
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Gelbach PE, Zheng D, Fraser SE, White KL, Graham NA, Finley SD. Kinetic and data-driven modeling of pancreatic β-cell central carbon metabolism and insulin secretion. PLoS Comput Biol 2022; 18:e1010555. [PMID: 36251711 PMCID: PMC9612825 DOI: 10.1371/journal.pcbi.1010555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/27/2022] [Accepted: 09/08/2022] [Indexed: 11/06/2022] Open
Abstract
Pancreatic β-cells respond to increased extracellular glucose levels by initiating a metabolic shift. That change in metabolism is part of the process of glucose-stimulated insulin secretion and is of particular interest in the context of diabetes. However, we do not fully understand how the coordinated changes in metabolic pathways and metabolite products influence insulin secretion. In this work, we apply systems biology approaches to develop a detailed kinetic model of the intracellular central carbon metabolic pathways in pancreatic β-cells upon stimulation with high levels of glucose. The model is calibrated to published metabolomics datasets for the INS1 823/13 cell line, accurately capturing the measured metabolite fold-changes. We first employed the calibrated mechanistic model to estimate the stimulated cell's fluxome. We then used the predicted network fluxes in a data-driven approach to build a partial least squares regression model. By developing the combined kinetic and data-driven modeling framework, we gain insights into the link between β-cell metabolism and glucose-stimulated insulin secretion. The combined modeling framework was used to predict the effects of common anti-diabetic pharmacological interventions on metabolite levels, flux through the metabolic network, and insulin secretion. Our simulations reveal targets that can be modulated to enhance insulin secretion. The model is a promising tool to contextualize and extend the usefulness of metabolomics data and to predict dynamics and metabolite levels that are difficult to measure in vitro. In addition, the modeling framework can be applied to identify, explain, and assess novel and clinically-relevant interventions that may be particularly valuable in diabetes treatment.
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Affiliation(s)
- Patrick E. Gelbach
- Department of Biomedical Engineering, USC, Los Angeles, California, United States of America
| | - Dongqing Zheng
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
| | - Scott E. Fraser
- Translational Imaging Center, University of Southern California, Los Angeles, California, United States of America
| | - Kate L. White
- Departments of Biological Sciences and Chemistry, Bridge Institute, USC Michelson Center, USC, Los Angeles, California, United States of America
| | - Nicholas A. Graham
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
| | - Stacey D. Finley
- Department of Biomedical Engineering, USC, Los Angeles, California, United States of America
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
- Department of Quantitative and Computational Biology, USC, Los Angeles, California, United States of America
- * E-mail:
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5
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Wang Y, Li J, Lu D, Meng Q, Song N, Zhou H, Xiao X, Sun L, Zhu H. Integrated proteome and phosphoproteome analysis of interscapular brown adipose and subcutaneous white adipose tissues upon high fat diet feeding in mouse. J Proteomics 2022; 255:104500. [DOI: 10.1016/j.jprot.2022.104500] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 01/10/2022] [Accepted: 01/22/2022] [Indexed: 11/17/2022]
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6
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Perazza LR, Mitchell PL, Lizotte F, Jensen BAH, St-Pierre P, Trottier J, Barbier O, Mathieu P, Geraldes PM, Marette A. Fish oil replacement prevents, while docosahexaenoic acid-derived protectin DX mitigates end-stage-renal-disease in atherosclerotic diabetic mice. FASEB J 2021; 35:e21559. [PMID: 33835594 DOI: 10.1096/fj.202100073r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/04/2021] [Accepted: 03/15/2021] [Indexed: 12/31/2022]
Abstract
Diabetic nephropathy (DN) remains the major cause of end-stage renal disease (ESRD). We used high-fat/high-sucrose (HFHS)-fed LDLr-/- /ApoB100/100 mice with transgenic overexpression of IGFII in pancreatic β-cells (LRKOB100/IGFII) as a model of ESRD to test whether dietary long chain omega-3 polyunsaturated fatty acids LCω3FA-rich fish oil (FO) could prevent ESRD development. We further evaluated the potential of docosahexaenoic acid (DHA)-derived pro-resolving lipid mediators, 17-hydroxy-DHA (17-HDHA) and Protectin DX (PDX), to reverse established ESRD damage. HFHS-fed vehicle-treated LRKOB100/IGFII mice developed severe kidney dysfunction leading to ESRD, as revealed by advanced glomerular fibrosis and mesangial expansion along with reduced percent survival. The kidney failure outcome was associated with cardiac dysfunction, revealed by reduced heart rate and prolonged diastolic and systolic time. Dietary FO prevented kidney damage, lean mass loss, cardiac dysfunction, and death. 17-HDHA reduced podocyte foot process effacement while PDX treatment alleviated kidney fibrosis and mesangial expansion as compared to vehicle treatment. Only PDX therapy was effective at preserving the heart function and survival rate. These results show that dietary LCω3FA intake can prevent ESRD and cardiac dysfunction in LRKOB100/IGFII diabetic mice. Our data further reveals that PDX can protect against renal failure and cardiac dysfunction, offering a potential new therapeutic strategy against ESRD.
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Affiliation(s)
- Laís R Perazza
- Quebec Heart and Lung Institute, Laval University, Quebec, QC, Canada.,Institute of Nutrition and Functional Foods, Laval University, Quebec, QC, Canada
| | - Patricia L Mitchell
- Quebec Heart and Lung Institute, Laval University, Quebec, QC, Canada.,Institute of Nutrition and Functional Foods, Laval University, Quebec, QC, Canada
| | - Farah Lizotte
- Faculty of Medicine and Health Sciences, University of Sherbrook, Sherbrooke, QC, Canada
| | - Benjamin A H Jensen
- Quebec Heart and Lung Institute, Laval University, Quebec, QC, Canada.,Novo Nordisk Foundation Center for Basic Metabolic Research, Section for Human Genomics and Metagenomics in Metabolism, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philippe St-Pierre
- Quebec Heart and Lung Institute, Laval University, Quebec, QC, Canada.,Institute of Nutrition and Functional Foods, Laval University, Quebec, QC, Canada
| | - Jocelyn Trottier
- CHU-Québec Research Centre, Laval University, Québec, QC, Canada
| | - Olivier Barbier
- CHU-Québec Research Centre, Laval University, Québec, QC, Canada
| | - Patrick Mathieu
- Quebec Heart and Lung Institute, Laval University, Quebec, QC, Canada
| | - Pedro M Geraldes
- Faculty of Medicine and Health Sciences, University of Sherbrook, Sherbrooke, QC, Canada
| | - André Marette
- Quebec Heart and Lung Institute, Laval University, Quebec, QC, Canada.,Institute of Nutrition and Functional Foods, Laval University, Quebec, QC, Canada
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Patel MS, Mahmood S, Jung J, Rideout TC. Reprogramming of aerobic glycolysis in non-transformed mouse liver with pyruvate dehydrogenase complex deficiency. Physiol Rep 2021; 9:e14684. [PMID: 33400855 PMCID: PMC7785054 DOI: 10.14814/phy2.14684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/19/2022] Open
Abstract
The Pyruvate Dehydrogenase Complex (PDC), a key enzyme in glucose metabolism, catalyzes an irreversible oxidative decarboxylation reaction of pyruvate to acetyl‐CoA, linking the cytosolic glycolytic pathway to mitochondrial tricarboxylic acid cycle and oxidative phosphorylation. Earlier we reported a down‐regulation of several key hepatic lipogenic enzymes and their upstream regulators in liver‐specific PDC‐deficient mouse (L‐PDCKO model by deleting the Pdha1 gene). In this study we investigated gene expression profiles of key glycolytic enzymes and other proteins that respond to various metabolic stresses in liver from L‐PDCKO mice. Transcripts of several, such as hexokinase 2, phosphoglycerate kinase 1, pyruvate kinase muscle‐type 2, and lactate dehydrogenase B as well as those for the nonglycolysis‐related proteins, CD‐36, C/EBP homologous protein, and peroxisome proliferator‐activated receptor γ, were up‐regulated in L‐PDCKO liver whereas hypoxia‐induced factor‐1α, pyruvate dehydrogenase kinase 1 and Sirtuin 1 transcripts were down‐regulated. The protein levels of pyruvate kinase muscle‐type 2 and lactate dehydrogenase B were increased whereas that of lactate dehydrogenase A was decreased in PDC‐deficient mouse liver. Analysis of endoplasmic reticulum and oxidative stress indicators suggests that the L‐PDCKO liver showed evidence of the former but not the latter. These findings indicate that (i) liver‐specific PDC deficiency is sufficient to induce “aerobic glycolysis characteristic” in mouse liver, and (ii) the mechanism(s) responsible for these changes appears distinct from that which induces the Warburg effect in some cancer cells.
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Affiliation(s)
- Mulchand S Patel
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Saleh Mahmood
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Jiwon Jung
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Todd C Rideout
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, USA
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Metabolic Effects of Selective Deletion of Group VIA Phospholipase A 2 from Macrophages or Pancreatic Islet Beta-Cells. Biomolecules 2020; 10:biom10101455. [PMID: 33080873 PMCID: PMC7602969 DOI: 10.3390/biom10101455] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/08/2020] [Accepted: 10/13/2020] [Indexed: 12/11/2022] Open
Abstract
To examine the role of group VIA phospholipase A2 (iPLA2β) in specific cell lineages in insulin secretion and insulin action, we prepared mice with a selective iPLA2β deficiency in cells of myelomonocytic lineage, including macrophages (MØ-iPLA2β-KO), or in insulin-secreting β-cells (β-Cell-iPLA2β-KO), respectively. MØ-iPLA2β-KO mice exhibited normal glucose tolerance when fed standard chow and better glucose tolerance than floxed-iPLA2β control mice after consuming a high-fat diet (HFD). MØ-iPLA2β-KO mice exhibited normal glucose-stimulated insulin secretion (GSIS) in vivo and from isolated islets ex vivo compared to controls. Male MØ-iPLA2β-KO mice exhibited enhanced insulin responsivity vs. controls after a prolonged HFD. In contrast, β-cell-iPLA2β-KO mice exhibited impaired glucose tolerance when fed standard chow, and glucose tolerance deteriorated further when introduced to a HFD. β-Cell-iPLA2β-KO mice exhibited impaired GSIS in vivo and from isolated islets ex vivo vs. controls. β-Cell-iPLA2β-KO mice also exhibited an enhanced insulin responsivity compared to controls. These findings suggest that MØ iPLA2β participates in HFD-induced deterioration in glucose tolerance and that this mainly reflects an effect on insulin responsivity rather than on insulin secretion. In contrast, β-cell iPLA2β plays a role in GSIS and also appears to confer some protection against deterioration in β-cell functions induced by a HFD.
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9
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Wang X, Lai S, Ye Y, Hu Y, Pan D, Bai X, Shen J. Conditional knockout of pyruvate dehydrogenase in mouse pancreatic β‑cells causes morphological and functional changes. Mol Med Rep 2020; 21:1717-1726. [PMID: 32319629 PMCID: PMC7057776 DOI: 10.3892/mmr.2020.10993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/12/2019] [Indexed: 12/14/2022] Open
Abstract
Diabetes mellitus is a metabolic disorder predominantly caused by the dysfunction of pancreatic β-cells. This dysfunction is partly caused by the dysregulation of pyruvate dehydrogenase (PDH), which acts as an important mediator of pyruvate oxidation after glycolysis and fuels the tricarboxylic acid cycle. Previous studies have reported decreased PDH expression in rodent models and humans with type 2 diabetes mellitus (T2DM), suggesting that PDH may play an important role in the development of T2DM. However, the mechanism by which PDH affects insulin secretion and β-cell development is poorly understood. Using immunofluorescence staining, the present study found that the expression of pyruvate dehydrogenase E1-α subunit (PDHA1; encoded by the PDHA1 gene) in the islets of type 2 diabetic mice (db/db mice) was lower than in wild-type mice, which indicated the possible association between PDHA1and diabetes. To further understand this mechanism, an inducible, islet-specific PDHA1 knockout mouse (βKO) model was established. The phenotype was authenticated, and the blood glucose levels and islet function between the βKO and control mice were compared. Though no changes were found in food intake, development status, fasting blood glucose or weight between the groups, the level of insulin secretion at 30 min after glucose injection in the βKO group was significantly lower compared with the control group. Furthermore, the performed of the βKO mice on the intraperitoneal glucose tolerance test was visibly impaired when compared with the control mice. Pancreatic tissues were collected for hematoxylin and eosin staining, immunohistochemical and confocal laser-scanning microscopy analysis. Examination of the islets from the βKO mouse model indicated that abolishing the expression of PDH caused a compensatory islet enlargement and impaired insulin secretion.
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Affiliation(s)
- Xiao Wang
- Shunde Hospital of Southern Medical University, Foshan, Guangdong 528308, P.R. China
| | - Shuchang Lai
- The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan 570100, P.R. China
| | - Yanshi Ye
- Department of Endocrinology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong 510000, P.R. China
| | - Yuanyuan Hu
- Shenzhen Nan Shan Hospital, Shenzhen, Guangdong 518052, P.R. China
| | - Daoyan Pan
- Department of Endocrinology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong 510000, P.R. China
| | - Xiaochun Bai
- Department of Endocrinology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong 510000, P.R. China
| | - Jie Shen
- Department of Endocrinology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong 510000, P.R. China
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10
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Hori S, Hiramuki Y, Nishimura D, Sato F, Sehara-Fujisawa A. PDH‐mediated metabolic flow is critical for skeletal muscle stem cell differentiation and myotube formation during regeneration in mice. FASEB J 2019; 33:8094-8109. [DOI: 10.1096/fj.201802479r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Shimpei Hori
- Department of Growth RegulationInstitute for Frontier Life and Medical SciencesKyoto University Kyoto Japan
| | - Yosuke Hiramuki
- Department of Growth RegulationInstitute for Frontier Life and Medical SciencesKyoto University Kyoto Japan
- Human Biology DivisionFred Hutchinson Cancer Research Center Seattle Washington USA
| | - Daigo Nishimura
- Department of Growth RegulationInstitute for Frontier Life and Medical SciencesKyoto University Kyoto Japan
| | - Fuminori Sato
- Department of Growth RegulationInstitute for Frontier Life and Medical SciencesKyoto University Kyoto Japan
| | - Atsuko Sehara-Fujisawa
- Department of Growth RegulationInstitute for Frontier Life and Medical SciencesKyoto University Kyoto Japan
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11
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Svensson K, Dent JR, Tahvilian S, Martins VF, Sathe A, Ochala J, Patel MS, Schenk S. Defining the contribution of skeletal muscle pyruvate dehydrogenase α1 to exercise performance and insulin action. Am J Physiol Endocrinol Metab 2018; 315:E1034-E1045. [PMID: 30153068 PMCID: PMC6293170 DOI: 10.1152/ajpendo.00241.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The pyruvate dehydrogenase complex (PDC) converts pyruvate to acetyl-CoA and is an important control point for carbohydrate (CHO) oxidation. However, the importance of the PDC and CHO oxidation to muscle metabolism and exercise performance, particularly during prolonged or high-intensity exercise, has not been fully defined especially in mature skeletal muscle. To this end, we determined whether skeletal muscle-specific loss of pyruvate dehydrogenase alpha 1 ( Pdha1), which is a critical subunit of the PDC, impacts resting energy metabolism, exercise performance, or metabolic adaptation to high-fat diet (HFD) feeding. For this, we generated a tamoxifen (TMX)-inducible Pdha1 knockout (PDHmKO) mouse, in which PDC activity is temporally and specifically ablated in adult skeletal muscle. We assessed energy expenditure, ex vivo muscle contractile performance, and endurance exercise capacity in PDHmKO mice and wild-type (WT) littermates. Additionally, we studied glucose homeostasis and insulin sensitivity in muscle after 12 wk of HFD feeding. TMX administration largely ablated PDHα in skeletal muscle of adult PDHmKO mice but did not impact energy expenditure, muscle contractile function, or low-intensity exercise performance. Additionally, there were no differences in muscle insulin sensitivity or body composition in PDHmKO mice fed a control or HFD, as compared with WT mice. However, exercise capacity during high-intensity exercise was severely impaired in PDHmKO mice, in parallel with a large increase in plasma lactate concentration. In conclusion, although skeletal muscle PDC is not a major contributor to resting energy expenditure or long-duration, low-intensity exercise performance, it is necessary for optimal performance during high-intensity exercise.
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Affiliation(s)
- Kristoffer Svensson
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California
| | - Jessica R Dent
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California
| | - Shahriar Tahvilian
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California
| | - Vitor F Martins
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California
| | - Abha Sathe
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California
| | - Julien Ochala
- School of Basic and Medical Biosciences, Faculty of Life Sciences & Medicine, King's College London , London , United Kingdom
| | - Mulchand S Patel
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Simon Schenk
- Department of Orthopaedic Surgery, University of California San Diego , La Jolla, California
- Biomedical Sciences Graduate Program, University of California San Diego , La Jolla, California
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12
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Esguerra JLS, Nagao M, Ofori JK, Wendt A, Eliasson L. MicroRNAs in islet hormone secretion. Diabetes Obes Metab 2018; 20 Suppl 2:11-19. [PMID: 30230181 DOI: 10.1111/dom.13382] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/10/2018] [Accepted: 05/23/2018] [Indexed: 12/12/2022]
Abstract
Pancreatic islet hormone secretion is central in the maintenance of blood glucose homeostasis. During development of hyperglycaemia, the β-cell is under pressure to release more insulin to compensate for increased insulin resistance. Failure of the β-cells to secrete enough insulin results in type 2 diabetes (T2D). MicroRNAs (miRNAs) are short non-coding RNA molecules suitable for rapid regulation of the changes in target gene expression needed in β-cell adaptations. Moreover, miRNAs are involved in the maintenance of α-cell and β-cell phenotypic identities via cell-specific, or cell-enriched expression. Although many of the abundant miRNAs are highly expressed in both cell types, recent research has focused on the role of miRNAs in β-cells. It has been shown that highly abundant miRNAs, such as miR-375, are involved in several cellular functions indispensable in maintaining β-cell phenotypic identity, almost acting as "housekeeping genes" in the context of hormone secretion. Despite the abundance and importance of miR-375, it has not been shown to be differentially expressed in T2D islets. On the contrary, the less abundant miRNAs such as miR-212/miR-132, miR-335, miR-130a/b and miR-152 are deregulated in T2D islets, wherein the latter three miRNAs were shown to play key roles in regulating β-cell metabolism. In this review, we focus on β-cell function and describe miRNAs involved in insulin biosynthesis and processing, glucose uptake and metabolism, electrical activity and Ca2+ -influx and exocytosis of the insulin granules. We present current status on miRNA regulation in α-cells, and finally we discuss the involvement of miRNAs in β-cell dysfunction underlying T2D pathogenesis.
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Affiliation(s)
- Jonathan L S Esguerra
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Mototsugu Nagao
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Jones K Ofori
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
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13
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Kirkley AG, Carmean CM, Ruiz D, Ye H, Regnier SM, Poudel A, Hara M, Kamau W, Johnson DN, Roberts AA, Parsons PJ, Seino S, Sargis RM. Arsenic exposure induces glucose intolerance and alters global energy metabolism. Am J Physiol Regul Integr Comp Physiol 2018; 314:R294-R303. [PMID: 29118024 PMCID: PMC5867677 DOI: 10.1152/ajpregu.00522.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 12/15/2022]
Abstract
Environmental pollutants acting as endocrine-disrupting chemicals (EDCs) are recognized as potential contributors to metabolic disease pathogenesis. One such pollutant, arsenic, contaminates the drinking water of ~100 million people globally and has been associated with insulin resistance and diabetes in epidemiological studies. Despite these observations, the precise metabolic derangements induced by arsenic remain incompletely characterized. In the present study, the impact of arsenic on in vivo metabolic physiology was examined in 8-wk-old male C57BL/6J mice exposed to 50 mg/l inorganic arsenite in their drinking water for 8 wk. Glucose metabolism was assessed via in vivo metabolic testing, and feeding behavior was analyzed using indirect calorimetry in metabolic cages. Pancreatic islet composition was assessed via immunofluorescence microscopy. Arsenic-exposed mice exhibited impaired glucose tolerance compared with controls; however, no difference in peripheral insulin resistance was noted between groups. Instead, early insulin release during glucose challenge was attenuated relative to the rise in glycemia. Despite decreased insulin secretion, pancreatic β-cell mass was not altered, suggesting that arsenic primarily disrupts β-cell function. Finally, metabolic cage analyses revealed that arsenic exposure induced novel alterations in the diurnal rhythm of food intake and energy metabolism. Taken together, these data suggest that arsenic exposure impairs glucose tolerance through functional impairments in insulin secretion from β-cells rather than by augmenting peripheral insulin resistance. Further elucidation of the mechanisms underlying arsenic-induced behavioral and β-cell-specific metabolic disruptions will inform future intervention strategies to address this ubiquitous environmental contaminant and novel diabetes risk factor.
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Affiliation(s)
- Andrew G Kirkley
- Committee on Molecular Pathogenesis and Molecular Medicine, University of Chicago , Chicago, Illinois
- University of Chicago , Chicago, Illinois
| | - Christopher M Carmean
- Division of Molecular and Metabolic Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine , Kobe , Japan
| | - Daniel Ruiz
- Committee on Molecular Metabolism and Nutrition, University of Chicago , Chicago, Illinois
- University of Chicago , Chicago, Illinois
| | - Honggang Ye
- Section of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Chicago , Chicago, Illinois
- University of Chicago , Chicago, Illinois
| | - Shane M Regnier
- Committee on Molecular Metabolism and Nutrition, University of Chicago , Chicago, Illinois
- University of Chicago , Chicago, Illinois
| | - Ananta Poudel
- Section of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Chicago , Chicago, Illinois
- University of Chicago , Chicago, Illinois
| | - Manami Hara
- Section of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Chicago , Chicago, Illinois
- University of Chicago , Chicago, Illinois
| | | | | | - Austin A Roberts
- Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health , Albany, New York
- Department of Environmental Health Sciences, The University at Albany, State University of New York , Albany, New York
| | - Patrick J Parsons
- Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health , Albany, New York
- Department of Environmental Health Sciences, The University at Albany, State University of New York , Albany, New York
| | - Susumu Seino
- Division of Molecular and Metabolic Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine , Kobe , Japan
| | - Robert M Sargis
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Illinois at Chicago , Chicago, Illinois
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14
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Abstract
The pancreatic β-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Research on Aging, Novato, California; and Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmo, Sweden
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15
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Ofori JK, Salunkhe VA, Bagge A, Vishnu N, Nagao M, Mulder H, Wollheim CB, Eliasson L, Esguerra JLS. Elevated miR-130a/miR130b/miR-152 expression reduces intracellular ATP levels in the pancreatic beta cell. Sci Rep 2017; 7:44986. [PMID: 28332581 PMCID: PMC5362944 DOI: 10.1038/srep44986] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 02/17/2017] [Indexed: 12/16/2022] Open
Abstract
MicroRNAs have emerged as important players of gene regulation with significant impact in diverse disease processes. In type-2 diabetes, in which impaired insulin secretion is a major factor in disease progression, dysregulated microRNA expression in the insulin-secreting pancreatic beta cell has been widely-implicated. Here, we show that miR-130a-3p, miR-130b-3p, and miR-152-3p levels are elevated in the pancreatic islets of hyperglycaemic donors, corroborating previous findings about their upregulation in the islets of type-2 diabetes model Goto-Kakizaki rats. We demonstrated negative regulatory effects of the three microRNAs on pyruvate dehydrogenase E1 alpha (PDHA1) and on glucokinase (GCK) proteins, which are both involved in ATP production. Consequently, we found both proteins to be downregulated in the Goto-Kakizaki rat islets, while GCK mRNA expression showed reduced trend in the islets of type-2 diabetes donors. Overexpression of any of the three microRNAs in the insulin-secreting INS-1 832/13 cell line resulted in altered dynamics of intracellular ATP/ADP ratio ultimately perturbing fundamental ATP-requiring beta cell processes such as glucose-stimulated insulin secretion, insulin biosynthesis and processing. The data further strengthen the wide-ranging influence of microRNAs in pancreatic beta cell function, and hence their potential as therapeutic targets in type-2 diabetes.
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Affiliation(s)
- Jones K Ofori
- Islet Cell Exocytosis, Department of Clinical Sciences-Malmö, Lund University, Malmö, 205 02, Sweden.,Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Vishal A Salunkhe
- Islet Cell Exocytosis, Department of Clinical Sciences-Malmö, Lund University, Malmö, 205 02, Sweden.,Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Annika Bagge
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden.,Molecular Metabolism, Department of Clinical Sciences-Malmö, Lund University, Malmö, 20502, Sweden
| | - Neelanjan Vishnu
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden.,Molecular Metabolism, Department of Clinical Sciences-Malmö, Lund University, Malmö, 20502, Sweden
| | - Mototsugu Nagao
- Islet Cell Exocytosis, Department of Clinical Sciences-Malmö, Lund University, Malmö, 205 02, Sweden.,Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Hindrik Mulder
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden.,Molecular Metabolism, Department of Clinical Sciences-Malmö, Lund University, Malmö, 20502, Sweden
| | - Claes B Wollheim
- Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden.,Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, 1211, Switzerland
| | - Lena Eliasson
- Islet Cell Exocytosis, Department of Clinical Sciences-Malmö, Lund University, Malmö, 205 02, Sweden.,Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Jonathan L S Esguerra
- Islet Cell Exocytosis, Department of Clinical Sciences-Malmö, Lund University, Malmö, 205 02, Sweden.,Lund University Diabetes Centre, Skåne University Hospital, Lund and Malmö, Sweden
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16
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Abu Bakar Sajak A, Mediani A, Maulidiani, Ismail A, Abas F. Metabolite Variation in Lean and Obese Streptozotocin (STZ)-Induced Diabetic Rats via 1H NMR-Based Metabolomics Approach. Appl Biochem Biotechnol 2016; 182:653-668. [PMID: 27995574 DOI: 10.1007/s12010-016-2352-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/28/2016] [Indexed: 12/25/2022]
Abstract
Diabetes mellitus (DM) is considered as a complex metabolic disease because it affects the metabolism of glucose and other metabolites. Although many diabetes studies have been conducted in animal models throughout the years, the pathogenesis of this disease, especially between lean diabetes (ND + STZ) and obese diabetes (OB + STZ), is still not fully understood. In this study, the urine from ND + STZ, OB + STZ, lean/control (ND), and OB + STZ rats were collected and compared by using 1H NMR metabolomics. The results from multivariate data analysis (MVDA) showed that the diabetic groups (ND + STZ and OB + STZ) have similarities and dissimilarities for a certain level of metabolites. Differences between ND + STZ and OB + STZ were particularly noticeable in the synthesis of ketone bodies, branched-chain amino acid (BCAA), and sensitivity towards the oral T2DM diabetes drug metformin. This finding suggests that the ND + STZ group was more similar to the T1DM model and OB + STZ to the T2DM model. In addition, we also managed to identify several pathways and metabolism aspects shared by obese (OB) and OB + STZ. The results from this study are useful in developing drug target-based research as they can increase understanding regarding the cause and effect of DM.
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Affiliation(s)
- Azliana Abu Bakar Sajak
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Ahmed Mediani
- Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Maulidiani
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Amin Ismail
- Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Faridah Abas
- Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia. .,Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
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17
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McCommis KS, Hodges WT, Bricker DK, Wisidagama DR, Compan V, Remedi MS, Thummel CS, Finck BN. An ancestral role for the mitochondrial pyruvate carrier in glucose-stimulated insulin secretion. Mol Metab 2016; 5:602-614. [PMID: 27656398 PMCID: PMC5021712 DOI: 10.1016/j.molmet.2016.06.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 06/24/2016] [Accepted: 06/30/2016] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE Transport of pyruvate into the mitochondrial matrix by the Mitochondrial Pyruvate Carrier (MPC) is an important and rate-limiting step in its metabolism. In pancreatic β-cells, mitochondrial pyruvate metabolism is thought to be important for glucose sensing and glucose-stimulated insulin secretion. METHODS To evaluate the role that the MPC plays in maintaining systemic glucose homeostasis, we used genetically-engineered Drosophila and mice with loss of MPC activity in insulin-producing cells. RESULTS In both species, MPC deficiency results in elevated blood sugar concentrations and glucose intolerance accompanied by impaired glucose-stimulated insulin secretion. In mouse islets, β-cell MPC-deficiency resulted in decreased respiration with glucose, ATP-sensitive potassium (KATP) channel hyperactivity, and impaired insulin release. Moreover, treatment of pancreas-specific MPC knockout mice with glibenclamide, a sulfonylurea KATP channel inhibitor, improved defects in islet insulin secretion and abnormalities in glucose homeostasis in vivo. Finally, using a recently-developed biosensor for MPC activity, we show that the MPC is rapidly stimulated by glucose treatment in INS-1 insulinoma cells suggesting that glucose sensing is coupled to mitochondrial pyruvate carrier activity. CONCLUSIONS Altogether, these studies suggest that the MPC plays an important and ancestral role in insulin-secreting cells in mediating glucose sensing, regulating insulin secretion, and controlling systemic glycemia.
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Key Words
- DILP2, Drosophila insulin-like peptide 2
- Diabetes
- Drosophila
- GSIS, glucose-stimulated insulin secretion
- GTT, glucose tolerance test
- IMM, inner mitochondrial membrane
- IPCs, Insulin-producing Cells
- ITT, insulin tolerance test
- Insulin
- MPC1 and MPC2, Mitochondrial Pyruvate Carrier 1 and 2
- Mitochondria
- OCR, oxygen consumption rates
- Pdx1, pancreatic and duodenal homeobox 1
- Pyruvate
- RESPYR, REporter Sensitive to PYRuvate
- Stimulus-coupled secretion
- β-Cell
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Affiliation(s)
- Kyle S McCommis
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Wesley T Hodges
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Daniel K Bricker
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dona R Wisidagama
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Vincent Compan
- Institute of Functional Genomics, Labex ICST; INSERM U1191, CNRS UMR5203; University of Montpellier, Montpellier, France
| | - Maria S Remedi
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Carl S Thummel
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Brian N Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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18
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Mahmood S, Birkaya B, Rideout TC, Patel MS. Lack of mitochondria-generated acetyl-CoA by pyruvate dehydrogenase complex downregulates gene expression in the hepatic de novo lipogenic pathway. Am J Physiol Endocrinol Metab 2016; 311:E117-27. [PMID: 27166281 PMCID: PMC4967143 DOI: 10.1152/ajpendo.00064.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/03/2016] [Indexed: 12/20/2022]
Abstract
During the absorptive state, the liver stores excess glucose as glycogen and synthesizes fatty acids for triglyceride synthesis for export as very low density lipoproteins. For de novo synthesis of fatty acids from glucose, the mitochondrial pyruvate dehydrogenase complex (PDC) is the gatekeeper for the generation of acetyl-CoA from glucose-derived pyruvate. Here, we tested the hypothesis that limiting the supply of PDC-generated acetyl-CoA from glucose would have an impact on expression of key genes in the lipogenic pathway. In the present study, although the postnatal growth of liver-specific PDC-deficient (L-PDCKO) male mice was largely unaltered, the mice developed hyperinsulinemia with lower blood glucose levels in the fed state. Serum and liver lipid triglyceride and cholesterol levels remained unaltered in L-PDCKO mice. Expression of several key genes (ACL, ACC1) in the lipogenic pathway and their upstream regulators (LXR, SREBP1, ChREBP) as well as several genes in glucose metabolism (Pklr, G6pd2, Pck1) and fatty acid oxidation (FAT, Cpt1a) was downregulated in livers from L-PDCKO mice. Interestingly, there was concomitant upregulation of lipogenic genes in adipose tissue from L-PDCKO mice. Although, the total hepatic acetyl-CoA content remained unaltered in L-PDCKO mice, modified acetylation profiles of proteins in the nuclear compartment suggested an important role for PDC-generated acetyl-CoA in gene expression in de novo fatty acid synthesis in the liver. This finding has important implications for the regulation of hepatic lipid synthesis in pathological states.
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Affiliation(s)
- Saleh Mahmood
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, and
| | - Barbara Birkaya
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, and
| | - Todd C Rideout
- Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, New York
| | - Mulchand S Patel
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, and
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19
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Liu L, Lou Q, Guo X, Yuan L, Shen L, Sun Z, Zhao F, Dai X, Huang J, Yang H, Mordes JP. Management status and its predictive factors in patients with type 2 diabetes in China: A Nationwide Multicenter Study: A Nationwide Multicenter Study. Diabetes Metab Res Rev 2015; 31:811-6. [PMID: 26455830 DOI: 10.1002/dmrr.2757] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 10/08/2015] [Accepted: 10/08/2015] [Indexed: 02/05/2023]
Abstract
BACKGROUND The prevalence of type 2 diabetes in China is increasing rapidly. Appropriate management of glycemia, blood pressure and dyslipidemia in this population is a major public health concern. OBJECTIVE The aim of this study was to assess metabolic control including glycated hemoglobin A1c (HbA1c ), blood pressure (BP) and low density lipoprotein cholesterol (LDL-c), in a large sample of patients with type 2 diabetes in China and to identify factors that correlated with the achievement of HbA1c, BP and LDL-c goals (ABCs). METHOD A nationwide survey was conducted in 50 medical centres across China from April to July of 2010. Baseline information on demographics, medical history, HbA1c , BP and LDL-c levels were measured in 5961 patients with type 2 diabetes. RESULTS Mean age, body mass index (BMI) and HbA1c were 59.5 ± 1.3 years, 24.5 ± 4.1 kg/m(2) and 8.3 ± 2.2%, respectively. With respect to generally accepted ABC treatment goals, 35.2% of participants had HbA1c <7%; 35.5% had BP < 140/80 mmHg, and 45.1% had LDL-c < 100 mg/dl. The proportion of patients who met all three targets was only 5.4%. Logistic regression revealed that smoking (P=0.000), higher BMI (P=0.001) and insulin use (P=0.000) were statistically significant predictors of failing to meet ABC targets. CONCLUSION The percentage of Chinese patients with type 2 diabetes who met recommended targets for HbA1c , BP and LDL-c in 2010 was low. Smoking, higher BMI and insulin use were the strongest determinants of failing to meet ABC targets.
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Affiliation(s)
- Lin Liu
- Jiangsu Province Hospital on Integration of Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Qingqing Lou
- Jiangsu Province Hospital on Integration of Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Xiaohui Guo
- Department of Endocrinology, Peking University First Hospital, #8 Xishiku Street, Beijing, China
| | - Li Yuan
- Department of Endocrinology, West China Medical School, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Li Shen
- Department of Endocrinology, Peking University First Hospital, Beijing, 100034, China
| | - Zilin Sun
- Institute of Diabetes, Zhongda Hospital, Medical School, Southeast University, Nanjing, Jiangsu, 210009, China
| | - Fang Zhao
- Department of Endocrinology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Xia Dai
- Department of Endocrinology, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Jin Huang
- Nursing Department, Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Huiying Yang
- Department of Endocrinology, Metabolism, First Affiliated Hospital of Kunming Medical College, Kunming, Yunnan, 650032, China
| | - John P Mordes
- UMass Medical School, 364 Plantation Street LRB 222, Worcester
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20
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Mitochondrial pyruvate transport: a historical perspective and future research directions. Biochem J 2015; 466:443-54. [PMID: 25748677 DOI: 10.1042/bj20141171] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pyruvate is the end-product of glycolysis, a major substrate for oxidative metabolism, and a branching point for glucose, lactate, fatty acid and amino acid synthesis. The mitochondrial enzymes that metabolize pyruvate are physically separated from cytosolic pyruvate pools and rely on a membrane transport system to shuttle pyruvate across the impermeable inner mitochondrial membrane (IMM). Despite long-standing acceptance that transport of pyruvate into the mitochondrial matrix by a carrier-mediated process is required for the bulk of its metabolism, it has taken almost 40 years to determine the molecular identity of an IMM pyruvate carrier. Our current understanding is that two proteins, mitochondrial pyruvate carriers MPC1 and MPC2, form a hetero-oligomeric complex in the IMM to facilitate pyruvate transport. This step is required for mitochondrial pyruvate oxidation and carboxylation-critical reactions in intermediary metabolism that are dysregulated in several common diseases. The identification of these transporter constituents opens the door to the identification of novel compounds that modulate MPC activity, with potential utility for treating diabetes, cardiovascular disease, cancer, neurodegenerative diseases, and other common causes of morbidity and mortality. The purpose of the present review is to detail the historical, current and future research investigations concerning mitochondrial pyruvate transport, and discuss the possible consequences of altered pyruvate transport in various metabolic tissues.
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21
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Matsunaga T, Li S, Adachi T, Joo E, Gu N, Yamazaki H, Yasuda K, Kondoh T, Tsuda K. Hyperoxia reverses glucotoxicity-induced inhibition of insulin secretion in rat INS-1 β cells. Biosci Biotechnol Biochem 2014; 78:843-50. [PMID: 25035988 DOI: 10.1080/09168451.2014.905175] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chronic hyperglycemia has deleterious effects on pancreatic β-cell function, a process known as glucotoxicity. This study examined whether chronic high glucose (CHG) induces cellular hypoxia in rat INS-1 β cells, and whether hyperoxia (35% O2) can reverse glucotoxicity-induced inhibition of insulin secretion. CHG (33.3 mm, 96 h) reduced insulin secretion, and down-regulated insulin and pancreatic duodenal homeobox factor 1 gene expression. CHG also increased intracellular pimonidazole-protein adducts, a marker for hypoxia. CHG also enhanced hypoxia-inducible factor 1α (HIF-1α) protein expression and its DNA-binding activity, which was accompanied by a decrease in mRNA expression of glucose transporter 2 (GLUT2), glucokinase and uncoupling protein-2 and an increase in mRNA expression of GLUT1 and pyruvate dehydrogenase kinase 1. Hyperoxia restored the decrease in insulin secretion and the gene expression except for GLUT2, and suppressed intracellular hypoxia and HIF-1α activation. These results suggest that glucotoxicity may cause β-cell hypoxia. Hyperoxia might prevent glucotoxicity-induced β-cell dysfunction and improve insulin secretion.
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Affiliation(s)
- Tetsuro Matsunaga
- a Faculty of Health and Living Sciences Education , Naruto University of Education , Naruto , Japan
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22
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Patel MS, Srinivasan M, Strutt B, Mahmood S, Hill DJ. Featured Article: Beta cell specific pyruvate dehydrogenase alpha gene deletion results in a reduced islet number and β-cell mass postnatally. Exp Biol Med (Maywood) 2014; 239:975-985. [PMID: 24845368 DOI: 10.1177/1535370214531895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The ability of pancreatic β-cells to undertake glucose-stimulated insulin secretion (GSIS) depends on the generation of adenosine triphosphate (ATP) within the mitochondria from pyruvate, a major rate-limiting enzyme being pyruvate dehydrogenase (PDH) complex (PDC). However, glucose metabolism also controls β-cell mass. To examine the role of PDC in the regulation of pancreatic β-cell development and maturation, we generated β-cell-targeted PDHα subunit knock-out male mice (β-PDHKO) and compared these with control males (β-PDHCT) from birth until 6-8 weeks age. Pancreas morphology, transcription factor expression, pancreatic insulin content, and circulating glucose and insulin values were compared. Compared to β-PDHCT male mice, β-PDHKO animals had significantly reduced pancreatic insulin content from birth, a lower serum insulin content from day 15, and relative hyperglycemia from day 30. Isolated islets from β-PDHKO mice demonstrated a reduced GSIS. The number of islets per pancreatic area, mean islet area, and the proportion of islet cells that were β-cells were all reduced in β-PDHKO animals. Similarly the number of insulin-immunopositive, extra-islet small endocrine cell clusters, a possible source of β-cell progenitors, was lower in β-PDHKO mice. Analysis of pancreatic expression of transcription factors responsible for β-cell lineage commitment, proliferation, and maturation, Pdx1, Neurogenin3, and NeuroD1 showed that mRNA abundance was reduced in the β-PDHKO. This demonstrates that PDC is not only required for insulin expression and glucose-stimulated secretion, but also directly influences β-cell growth and maturity, and positions glucose metabolism as a direct regulator of β-cell mass and plasticity.
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Affiliation(s)
- Mulchand S Patel
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo 14214, NY
| | - Malathi Srinivasan
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo 14214, NY
| | - Brenda Strutt
- Lawson Research Institute, St. Joseph's Health Centre, London, Ontario N6A 4V2, Canada
| | - Saleh Mahmood
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo 14214, NY
| | - David J Hill
- Lawson Research Institute, St. Joseph's Health Centre, London, Ontario N6A 4V2, Canada Department of Medicine, Physiology, and Paediatrics, University of Western Ontario, London, Ontario N6A 3K7, Canada
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23
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Wolden-Kirk H, Rondas D, Bugliani M, Korf H, Van Lommel L, Brusgaard K, Christesen HT, Schuit F, Proost P, Masini M, Marchetti P, Eizirik DL, Overbergh L, Mathieu C. Discovery of molecular pathways mediating 1,25-dihydroxyvitamin D3 protection against cytokine-induced inflammation and damage of human and male mouse islets of Langerhans. Endocrinology 2014; 155:736-47. [PMID: 24424042 DOI: 10.1210/en.2013-1409] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protection against insulitis and diabetes by active vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), in nonobese diabetic mice has until now mainly been attributed to its immunomodulatory effects, but also protective effects of this hormone on inflammation-induced β-cell death have been reported. The aim of this study was to clarify the molecular mechanisms by which 1,25(OH)2D3 contributes to β-cell protection against cytokine-induced β-cell dysfunction and death. Human and mouse islets were exposed to IL-1β and interferon-γ in the presence or absence of 1,25(OH)2D3. Effects on insulin secretion and β-cell survival were analyzed by glucose-stimulated insulin release and electron microscopy or Hoechst/propidium iodide staining, respectively. Gene expression profiles were assessed by Affymetrix microarrays. Nuclear factor-κB activity was tested, whereas effects on secreted chemokines/cytokines were confirmed by ELISA and migration studies. Cytokine exposure caused a significant increase in β-cell apoptosis, which was almost completely prevented by 1,25(OH)2D3. In addition, 1,25(OH)2D3 restored insulin secretion from cytokine-exposed islets. Microarray analysis of murine islets revealed that the expression of approximately 4000 genes was affected by cytokines after 6 and 24 hours (n = 4; >1.3-fold; P < .02), of which nearly 250 genes were modified by 1,25(OH)2D3. These genes belong to functional groups involved in immune response, chemotaxis, cell death, and pancreatic β-cell function/phenotype. In conclusion, these findings demonstrate a direct protective effect of 1,25(OH)2D3 against inflammation-induced β-cell dysfunction and death in human and murine islets, with, in particular, alterations in chemokine production by the islets. These effects may contribute to the beneficial effects of 1,25(OH)2D3 against the induction of autoimmune diabetes.
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Affiliation(s)
- H Wolden-Kirk
- Clinical and Experimental Endocrinology (H.W.-K., D.R., H.K., L.O., C.M.), University Hospital Gasthuisberg, Gene Expression Unit (L.V.L., F.S.), Department of Molecular and Cellular Medicine, Department of Microbiology and Immunology (P.P.), B-3000 Leuven, Belgium; Hans Christian Andersen Children's Hospital (H.W.-K., H.T.C.) and Department of Clinical Genetics (K.B., D.L.E.), Odense University Hospital, DK-5000, Odense, Denmark; Department of Endocrinology and Metabolism (M.B., P.M.), Metabolic Unit, and Department of General Pathology (M.M.), University of Pisa, Pisa, Italy; and Laboratory of Experimental Medicine (D.L.E.), Université Libre de Bruxelles, B-1070 Brussels, Belgium
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24
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Abstract
The pancreatic islet β cell senses circulating levels of calorigenic nutrients to secrete insulin according to the needs of the organism. Altered insulin secretion is linked to various disorders such as diabetes, hypoglycemic states, and cardiometabolic diseases. Fuel stimuli, including glucose, free fatty acids, and amino acids, promote insulin granule exocytosis primarily via their metabolism in β cells and the production of key signaling metabolites. This paper reviews our current knowledge of the pathways involved in both positive and negative metabolic signaling for insulin secretion and assesses the role of established and candidate metabolic coupling factors, keeping recent developments in focus.
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Affiliation(s)
- Marc Prentki
- Molecular Nutrition Unit, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, QC, Canada.
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25
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Akhmedov D, De Marchi U, Wollheim CB, Wiederkehr A. Pyruvate dehydrogenase E1α phosphorylation is induced by glucose but does not control metabolism-secretion coupling in INS-1E clonal β-cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1815-24. [PMID: 22809973 DOI: 10.1016/j.bbamcr.2012.07.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 06/25/2012] [Accepted: 07/09/2012] [Indexed: 12/24/2022]
Abstract
Glucose-induced insulin secretion from pancreatic β-cells depends on mitochondrial activation. In the organelle, glucose-derived pyruvate is metabolised along the oxidative and anaplerotic pathway to generate downstream signals leading to insulin granule exocytosis. Entry into the oxidative pathway is catalysed by pyruvate dehydrogenase (PDH) and controlled in part by phosphorylation of the PDH E1α subunit blocking enzyme activity. We find that glucose but not other nutrient secretagogues induce PDH E1α phosphorylation in INS-1E cells and rat islets. INS-1E cells and primary β-cells express pyruvate dehydrogenase kinase (PDK) 1, 2 and 3, which mediate the observed phosphorylation. In INS-1E cells, suppression of the two main isoforms, PDK1 and PDK3, almost completely prevented PDH E1α phosphorylation. Under basal glucose conditions, phosphorylation was barely detectable and therefore the enzyme almost fully active (90% of maximal). During glucose stimulation, PDH is only partially inhibited (to 78% of maximal). Preventing PDH phosphorylation in situ after suppression of PDK1, 2 and 3 neither enhanced pyruvate oxidation nor insulin secretion. In conclusion, although glucose stimulates E1α phosphorylation and therefore inhibits PDH activity, this control mechanism by itself does not alter metabolism-secretion coupling in INS-1E clonal β-cells.
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Affiliation(s)
- Dmitry Akhmedov
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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26
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Abstract
Considerable research has been conducted on mitochondrial biology as it pertains to aging. However, relatively little attention has been accorded the pyruvate dehydrogenase complex (PDC) relative to how we grow old and acquire age-related diseases. The purpose of this review is threefold: first, to describe the physiological chemistry of the PDC and define its place in normal cellular bioenergetics; second, to compare and contrast the pathogenesis and clinical features of congenital PDC deficiency with discrete examples of age-associated dysfunction of the complex; and third, to summarize recent findings in Caenorhabditis elegans that shed additional new light on the significance of the PDC to the aging process.
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Affiliation(s)
- Peter W Stacpoole
- Departments of Medicine (Division of Endocrinology and Metabolism) and Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
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27
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Sugden MC, Holness MJ. The pyruvate carboxylase-pyruvate dehydrogenase axis in islet pyruvate metabolism: Going round in circles? Islets 2011; 3:302-19. [PMID: 21934355 PMCID: PMC3329512 DOI: 10.4161/isl.3.6.17806] [Citation(s) in RCA: 36] [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] [Indexed: 12/24/2022] Open
Abstract
Pyruvate is the major product of glycolysis in pancreatic β-cells, and its ultimate metabolic fate depends on the relative activities of two enzymes. The first, pyruvate carboxylase (PC) replenishes oxaloacetate withdrawn from the tricarboxylic acid (TCA) cycle via the carboxylation of pyruvate to form oxaloacetate. Flux via PC is also involved in the formation of NADPH, one of several important coupling factors for insulin secretion. In most tissues, PC activity is enhanced by increased acetyl-CoA. The alternative fate of pyruvate is its oxidative decarboxylation to form acetyl-CoA via the pyruvate dehydrogenase complex (PDC). The ultimate fate of acetyl-CoA carbon is oxidation to CO2 via the TCA cycle, and so the PDC reaction results of the irreversible loss of glucose-derived carbon. Thus, PDC activity is stringently regulated. The mechanisms controlling PDC activity include end-product inhibition by increased acetyl-CoA, NADH and ATP, and its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDHKs 1-4). Here we review new developments in the regulation of the activities and expression of PC, PDC and the PDHKs in the pancreatic islet in relation to islet pyruvate disposition and glucose-stimulated insulin secretion (GSIS).
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Affiliation(s)
- Mary C Sugden
- Centre for Diabetes, Blizard Institute, Bart's and the London School of Medicine and Dentistry, London, UK.
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28
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Exercise increases insulin content and basal secretion in pancreatic islets in type 1 diabetic mice. EXPERIMENTAL DIABETES RESEARCH 2011; 2011:481427. [PMID: 21912535 PMCID: PMC3170797 DOI: 10.1155/2011/481427] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 05/17/2011] [Indexed: 11/28/2022]
Abstract
Exercise appears to improve glycemic control for people with type 1 diabetes (T1D). However, the mechanism responsible for this improvement is unknown. We hypothesized that exercise has a direct effect on the insulin-producing islets. Eight-week-old mice were divided into four groups: sedentary diabetic, exercised diabetic, sedentary control, and exercised control. The exercised groups participated in voluntary wheel running for 6 weeks. When compared to the control groups, the islet density, islet diameter, and β-cell proportion per islet were significantly lower in both sedentary and exercised diabetic groups and these alterations were not improved with exercise. The total insulin content and insulin secretion were significantly lower in sedentary diabetics compared to controls. Exercise significantly improved insulin content and insulin secretion in islets in basal conditions. Thus, some improvements in exercise-induced glycemic control in T1D mice may be due to enhancement of insulin content and secretion in islets.
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