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Campolo A, Maria Z, Lacombe VA. Diabetes Causes Significant Alterations in Pulmonary Glucose Transporter Expression. Metabolites 2024; 14:267. [PMID: 38786744 PMCID: PMC11123172 DOI: 10.3390/metabo14050267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 04/26/2024] [Accepted: 04/30/2024] [Indexed: 05/25/2024] Open
Abstract
Diabetes has been identified as a significant and independent risk factor for the development or increased severity of respiratory infections. However, the role of glucose transport in the healthy and diseased lung has received little attention. Specifically, the protein expression of the predominant glucose transporter (GLUT) isoforms in the adult lung remains largely to be characterized in both healthy and diabetic states. Type 1 diabetes was induced via streptozotocin and rescued via subcutaneous semi-osmotic insulin pump for 8 weeks. The gene and/or protein expression of the most predominant GLUT isoforms from Classes I and III, including the major insulin-sensitive isoform (i.e., GLUT4) and novel isoforms (i.e., GLUT-8 and GLUT-12), was quantified in the lung of healthy and diabetic mice via qRT-PCR and/or Western blotting. Pulmonary cell surface GLUT protein was measured using a biotinylated photolabeling assay, as a means to evaluate GLUT trafficking. Diabetic mice demonstrated significant alterations of total pulmonary GLUT protein expression, which were isoform- and location-dependent. Long-term insulin treatment rescued the majority of GLUT protein expression alterations in the lung during diabetes, as well as GLUT-4 and -8 trafficking to the pulmonary cell surface. These alterations in glucose homeostasis during diabetes may contribute to an increased severity of pulmonary infection during diabetes and may point to novel metabolic therapeutic strategies for diabetic patients with concurrent respiratory infections.
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Affiliation(s)
| | | | - Véronique A. Lacombe
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA; (A.C.); (Z.M.)
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Al Otaibi A, Al Shaikh Mubarak S, Al Hejji F, Almasaud A, Al Jami H, Iqbal J, Al Qarni A, Harbi NKA, Bakillah A. Thapsigargin and Tunicamycin Block SARS-CoV-2 Entry into Host Cells via Differential Modulation of Unfolded Protein Response (UPR), AKT Signaling, and Apoptosis. Cells 2024; 13:769. [PMID: 38727305 PMCID: PMC11083125 DOI: 10.3390/cells13090769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/05/2024] [Accepted: 04/27/2024] [Indexed: 05/13/2024] Open
Abstract
BACKGROUND SARS-Co-V2 infection can induce ER stress-associated activation of unfolded protein response (UPR) in host cells, which may contribute to the pathogenesis of COVID-19. To understand the complex interplay between SARS-Co-V2 infection and UPR signaling, we examined the effects of acute pre-existing ER stress on SARS-Co-V2 infectivity. METHODS Huh-7 cells were treated with Tunicamycin (TUN) and Thapsigargin (THA) prior to SARS-CoV-2pp transduction (48 h p.i.) to induce ER stress. Pseudo-typed particles (SARS-CoV-2pp) entry into host cells was measured by Bright GloTM luciferase assay. Cell viability was assessed by cell titer Glo® luminescent assay. The mRNA and protein expression was evaluated by RT-qPCR and Western Blot. RESULTS TUN (5 µg/mL) and THA (1 µM) efficiently inhibited the entry of SARS-CoV-2pp into host cells without any cytotoxic effect. TUN and THA's attenuation of virus entry was associated with differential modulation of ACE2 expression. Both TUN and THA significantly reduced the expression of stress-inducible ER chaperone GRP78/BiP in transduced cells. In contrast, the IRE1-XBP1s and PERK-eIF2α-ATF4-CHOP signaling pathways were downregulated with THA treatment, but not TUN in transduced cells. Insulin-mediated glucose uptake and phosphorylation of Ser307 IRS-1 and downstream p-AKT were enhanced with THA in transduced cells. Furthermore, TUN and THA differentially affected lipid metabolism and apoptotic signaling pathways. CONCLUSIONS These findings suggest that short-term pre-existing ER stress prior to virus infection induces a specific UPR response in host cells capable of counteracting stress-inducible elements signaling, thereby depriving SARS-Co-V2 of essential components for entry and replication. Pharmacological manipulation of ER stress in host cells might provide new therapeutic strategies to alleviate SARS-CoV-2 infection.
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Affiliation(s)
- Abeer Al Otaibi
- King Abdullah International Medical Research Center (KAIMRC), Eastern Region, Al Ahsa 31982, Saudi Arabia; (A.A.O.); (S.A.S.M.); (F.A.H.); (J.I.); (A.A.Q.)
- Biomedical Research Department, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Al Ahsa 36428, Saudi Arabia
- King Abdulaziz Hospital, Ministry of National Guard-Health Affairs (MNG-HA), Al Ahsa 36428, Saudi Arabia
| | - Sindiyan Al Shaikh Mubarak
- King Abdullah International Medical Research Center (KAIMRC), Eastern Region, Al Ahsa 31982, Saudi Arabia; (A.A.O.); (S.A.S.M.); (F.A.H.); (J.I.); (A.A.Q.)
- Biomedical Research Department, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Al Ahsa 36428, Saudi Arabia
- King Abdulaziz Hospital, Ministry of National Guard-Health Affairs (MNG-HA), Al Ahsa 36428, Saudi Arabia
| | - Fatimah Al Hejji
- King Abdullah International Medical Research Center (KAIMRC), Eastern Region, Al Ahsa 31982, Saudi Arabia; (A.A.O.); (S.A.S.M.); (F.A.H.); (J.I.); (A.A.Q.)
| | - Abdulrahman Almasaud
- Vaccine Development Unit, Department of Infectious Disease Research, King Abdullah International Medical Research Center, Riyadh 11481, Saudi Arabia; (A.A.); (H.A.J.); (N.K.A.H.)
| | - Haya Al Jami
- Vaccine Development Unit, Department of Infectious Disease Research, King Abdullah International Medical Research Center, Riyadh 11481, Saudi Arabia; (A.A.); (H.A.J.); (N.K.A.H.)
| | - Jahangir Iqbal
- King Abdullah International Medical Research Center (KAIMRC), Eastern Region, Al Ahsa 31982, Saudi Arabia; (A.A.O.); (S.A.S.M.); (F.A.H.); (J.I.); (A.A.Q.)
- Biomedical Research Department, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Al Ahsa 36428, Saudi Arabia
- King Abdulaziz Hospital, Ministry of National Guard-Health Affairs (MNG-HA), Al Ahsa 36428, Saudi Arabia
| | - Ali Al Qarni
- King Abdullah International Medical Research Center (KAIMRC), Eastern Region, Al Ahsa 31982, Saudi Arabia; (A.A.O.); (S.A.S.M.); (F.A.H.); (J.I.); (A.A.Q.)
- Biomedical Research Department, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Al Ahsa 36428, Saudi Arabia
- King Abdulaziz Hospital, Ministry of National Guard-Health Affairs (MNG-HA), Al Ahsa 36428, Saudi Arabia
| | - Naif Khalaf Al Harbi
- Vaccine Development Unit, Department of Infectious Disease Research, King Abdullah International Medical Research Center, Riyadh 11481, Saudi Arabia; (A.A.); (H.A.J.); (N.K.A.H.)
| | - Ahmed Bakillah
- King Abdullah International Medical Research Center (KAIMRC), Eastern Region, Al Ahsa 31982, Saudi Arabia; (A.A.O.); (S.A.S.M.); (F.A.H.); (J.I.); (A.A.Q.)
- Biomedical Research Department, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), Al Ahsa 36428, Saudi Arabia
- King Abdulaziz Hospital, Ministry of National Guard-Health Affairs (MNG-HA), Al Ahsa 36428, Saudi Arabia
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Mendez Garcia MF, Matsuzaki S, Batushansky A, Newhardt R, Kinter C, Jin Y, Mann SN, Stout MB, Gu H, Chiao YA, Kinter M, Humphries KM. Increased cardiac PFK-2 protects against high-fat diet-induced cardiomyopathy and mediates beneficial systemic metabolic effects. iScience 2023; 26:107131. [PMID: 37534142 PMCID: PMC10391959 DOI: 10.1016/j.isci.2023.107131] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 04/27/2023] [Accepted: 06/10/2023] [Indexed: 08/04/2023] Open
Abstract
A healthy heart adapts to changes in nutrient availability and energy demands. In metabolic diseases like type 2 diabetes (T2D), increased reliance on fatty acids for energy production contributes to mitochondrial dysfunction and cardiomyopathy. A principal regulator of cardiac metabolism is 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2), which is a central driver of glycolysis. We hypothesized that increasing PFK-2 activity could mitigate cardiac dysfunction induced by high-fat diet (HFD). Wild type (WT) and cardiac-specific transgenic mice expressing PFK-2 (GlycoHi) were fed a low fat or HFD for 16 weeks to induce metabolic dysfunction. Metabolic phenotypes were determined by measuring mitochondrial bioenergetics and performing targeted quantitative proteomic and metabolomic analysis. Increasing cardiac PFK-2 had beneficial effects on cardiac and mitochondrial function. Unexpectedly, GlycoHi mice also exhibited sex-dependent systemic protection from HFD, including increased glucose homeostasis. These findings support improving glycolysis via PFK-2 activity can mitigate mitochondrial and functional changes that occur with metabolic syndrome.
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Affiliation(s)
- Maria F. Mendez Garcia
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Satoshi Matsuzaki
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Albert Batushansky
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
- Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Ryan Newhardt
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Caroline Kinter
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Yan Jin
- Center for Translational Science, Florida International University, Port St. Lucie, FL, USA
| | - Shivani N. Mann
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Michael B. Stout
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Haiwei Gu
- Center for Translational Science, Florida International University, Port St. Lucie, FL, USA
| | - Ying Ann Chiao
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Michael Kinter
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Kenneth M. Humphries
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Bauzá-Thorbrügge M, Banke E, Chanclón B, Peris E, Wu Y, Musovic S, Jönsson C, Strålfors P, Rorsman P, Olofsson CS, Asterholm IW. Adipocyte-specific ablation of the Ca 2+ pump SERCA2 impairs whole-body metabolic function and reveals the diverse metabolic flexibility of white and brown adipose tissue. Mol Metab 2022; 63:101535. [PMID: 35760318 PMCID: PMC9287368 DOI: 10.1016/j.molmet.2022.101535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) transports Ca2+ from the cytosol into the ER and is essential for appropriate regulation of intracellular Ca2+ homeostasis. The objective of this study was to test the hypothesis that SERCA pumps are involved in the regulation of white adipocyte hormone secretion and other aspects of adipose tissue function and that this control is disturbed in obesity-induced type-2 diabetes. METHODS SERCA expression was measured in isolated human and mouse adipocytes as well as in whole mouse adipose tissue by Western blot and RT-qPCR. To test the significance of SERCA2 in adipocyte functionality and whole-body metabolism, we generated adipocyte-specific SERCA2 knockout mice. The mice were metabolically phenotyped by glucose tolerance and tracer studies, histological analyses, measurements of glucose-stimulated insulin release in isolated islets, and gene/protein expression analyses. We also tested the effect of pharmacological SERCA inhibition and genetic SERCA2 ablation in cultured adipocytes. Intracellular and mitochondrial Ca2+ levels were recorded with dual-wavelength ratio imaging and mitochondrial function was assessed by Seahorse technology. RESULTS We demonstrate that SERCA2 is downregulated in white adipocytes from patients with obesity and type-2 diabetes as well as in adipocytes from diet-induced obese mice. SERCA2-ablated adipocytes display disturbed Ca2+ homeostasis associated with upregulated ER stress markers and impaired hormone release. These adipocyte alterations are linked to mild lipodystrophy, reduced adiponectin levels, and impaired glucose tolerance. Interestingly, adipocyte-specific SERCA2 ablation leads to increased glucose uptake in white adipose tissue while glucose uptake is reduced in brown adipose tissue. This dichotomous effect on glucose uptake is due to differently regulated mitochondrial function. In white adipocytes, SERCA2 deficiency triggers an adaptive increase in FGF21, increased mitochondrial UCP1 levels, and increased oxygen consumption rate (OCR). In contrast, brown SERCA2 null adipocytes display reduced OCR despite increased mitochondrial content and UCP1 levels compared to wild type controls. CONCLUSIONS Our data suggest causal links between reduced white adipocyte SERCA2 levels, deranged adipocyte Ca2+ homeostasis, adipose tissue dysfunction and type-2 diabetes.
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Affiliation(s)
- Marco Bauzá-Thorbrügge
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Elin Banke
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Belén Chanclón
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Eduard Peris
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Yanling Wu
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Saliha Musovic
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Cecilia Jönsson
- Department of Biomedical and Clinical Sciences, Linköping University, SE-58185 Linköping, Sweden.
| | - Peter Strålfors
- Department of Biomedical and Clinical Sciences, Linköping University, SE-58185 Linköping, Sweden.
| | - Patrik Rorsman
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden; Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX4 7LE, UK.
| | - Charlotta S Olofsson
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
| | - Ingrid Wernstedt Asterholm
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 11, SE-405 30 Göteborg, Sweden.
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Czapiewski R, Batrakou DG, de Las Heras JI, Carter RN, Sivakumar A, Sliwinska M, Dixon CR, Webb S, Lattanzi G, Morton NM, Schirmer EC. Genomic loci mispositioning in Tmem120a knockout mice yields latent lipodystrophy. Nat Commun 2022; 13:321. [PMID: 35027552 PMCID: PMC8758788 DOI: 10.1038/s41467-021-27869-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 12/19/2021] [Indexed: 12/13/2022] Open
Abstract
Little is known about how the observed fat-specific pattern of 3D-spatial genome organisation is established. Here we report that adipocyte-specific knockout of the gene encoding nuclear envelope transmembrane protein Tmem120a disrupts fat genome organisation, thus causing a lipodystrophy syndrome. Tmem120a deficiency broadly suppresses lipid metabolism pathway gene expression and induces myogenic gene expression by repositioning genes, enhancers and miRNA-encoding loci between the nuclear periphery and interior. Tmem120a-/- mice, particularly females, exhibit a lipodystrophy syndrome similar to human familial partial lipodystrophy FPLD2, with profound insulin resistance and metabolic defects that manifest upon exposure to an obesogenic diet. Interestingly, similar genome organisation defects occurred in cells from FPLD2 patients that harbour nuclear envelope protein encoding LMNA mutations. Our data indicate TMEM120A genome organisation functions affect many adipose functions and its loss may yield adiposity spectrum disorders, including a miRNA-based mechanism that could explain muscle hypertrophy in human lipodystrophy.
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Affiliation(s)
- Rafal Czapiewski
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Dzmitry G Batrakou
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | | | - Roderick N Carter
- Molecular Metabolism Group, University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK
| | | | | | - Charles R Dixon
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Shaun Webb
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Giovanna Lattanzi
- CNR - National Research Council of Italy, Institute of Molecular Genetics "Luigi Luca Cavalli-Sforza", Unit of Bologna, Bologna, 40136, Italy
- IRCCS, Istituto Ortopedico Rizzoli, Bologna, 40136, Italy
| | - Nicholas M Morton
- Molecular Metabolism Group, University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK
| | - Eric C Schirmer
- Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3BF, UK.
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Mendez DA, Ortiz RM. Thyroid hormones and the potential for regulating glucose metabolism in cardiomyocytes during insulin resistance and T2DM. Physiol Rep 2021; 9:e14858. [PMID: 34405550 PMCID: PMC8371345 DOI: 10.14814/phy2.14858] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 12/30/2022] Open
Abstract
In order for the heart to maintain its continuous mechanical work and provide the systolic movement to uphold coronary blood flow, substantial synthesis of adenosine triphosphate (ATP) is required. Under normal conditions cardiac tissue utilizes roughly 70% fatty acids (FA), and 30% glucose for the production of ATP; however, during impaired metabolic conditions like insulin resistance and diabetes glucose metabolism is dysregulated and FA account for 99% of energy production. One of the major consequences of a shift in FA metabolism in cardiac tissue is an increase in reactive oxygen species (ROS) and lipotoxicity, which ultimately lead to mitochondrial dysfunction. Thyroid hormones (TH) have direct effects on cardiac function and glucose metabolism during impaired metabolic conditions suggesting that TH may improve glucose metabolism in an insulin resistant condition. None-classical TH signaling in the heart has shown to phosphorylate protein kinase B (Akt) and increase activity of phosphoinositide-3-kinase (PI3K), which are critical mediators in the insulin-stimulated glucose uptake pathway. Studies on peripheral tissues such as skeletal muscle and adipocytes have demonstrated TH treatment improved glucose intolerance in a diabetic model and increased insulin-regulated glucose transporter (GLUT4) mRNA levels. GLUT4 is a downstream target of thyroid response element (TRE), which demonstrates that THs regulate glucose via GLUT4. Elevated 3,5,3'-triiodothyronine (T3) increased glucose oxidation rate and decreased the glycolytic intermediate, fructose 6-phosphate (F6P) in cardiomyocytes, in addition to increasing mitochondrial biogenesis and pyruvate transport across the mitochondrial membrane. These findings along with a few other studies on T3 treatment in cardiac tissue suggest TH may improve glucose metabolism in an insulin resistant model and ameliorate the effects of diabetes and metabolic syndrome. This review highlights the potential benefits of exogenous TH on ameliorating metabolic dysfunction in the heart.
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Affiliation(s)
- Dora A. Mendez
- Department of Molecular & Cell BiologySchool of Natural SciencesUniversity of CaliforniaMercedCAUSA
| | - Rudy M. Ortiz
- Department of Molecular & Cell BiologySchool of Natural SciencesUniversity of CaliforniaMercedCAUSA
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Yang HW, Jiang YF, Lee HG, Jeon YJ, Ryu B. Ca 2+-Dependent Glucose Transport in Skeletal Muscle by Diphlorethohydroxycarmalol, an Alga Phlorotannin: In Vitro and In Vivo Study. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:8893679. [PMID: 33628395 PMCID: PMC7889350 DOI: 10.1155/2021/8893679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/21/2020] [Accepted: 01/13/2021] [Indexed: 12/31/2022]
Abstract
Diphlorethohydroxycarmalol (DPHC), a type of phlorotannin isolated from the marine alga Ishige okamurae, reportedly alleviates impaired glucose tolerance. However, the molecular mechanisms of DPHC regulatory activity and by which it exerts potential beneficial effects on glucose transport into skeletal myotubes to control glucose homeostasis remain largely unexplored. The aim of this study was to evaluate the effect of DPHC on cytosolic Ca2+ levels and its correlation with blood glucose transport in skeletal myotubes in vitro and in vivo. Cytosolic Ca2+ levels upon DPHC treatment were evaluated in skeletal myotubes and zebrafish larvae by Ca2+ imaging using Fluo-4. We investigated the effect of DPHC on the blood glucose level and glucose transport pathway in a hyperglycemic zebrafish. DPHC was shown to control blood glucose levels by accelerating glucose transport; this effect was associated with elevated cytosolic Ca2+ levels in skeletal myotubes. Moreover, the increased cytosolic Ca2+ level caused by DPHC can facilitate the Glut4/AMPK pathways of the skeletal muscle in activating glucose metabolism, thereby regulating muscle contraction through the regulation of expression of troponin I/C, CaMKII, and ATP. Our findings provide insights into the mechanism of DPHC activity in skeletal myotubes, suggesting that increased cytosolic Ca2+ levels caused by DPHC can promote glucose transport into skeletal myotubes to modulate blood glucose levels, thus indicating the potential use of DPHC in the prevention of diabetes.
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Affiliation(s)
- Hye-Won Yang
- Department of Marine Life Science, Jeju National University, Jeju 63243, Republic of Korea
| | - Yun-Fei Jiang
- Department of Marine Life Science, Jeju National University, Jeju 63243, Republic of Korea
| | - Hyo-Geun Lee
- Department of Marine Life Science, Jeju National University, Jeju 63243, Republic of Korea
| | - You-Jin Jeon
- Department of Marine Life Science, Jeju National University, Jeju 63243, Republic of Korea
- Marine Science Institute, Jeju National University, Jeju 63333, Republic of Korea
| | - BoMi Ryu
- Department of Marine Life Science, Jeju National University, Jeju 63243, Republic of Korea
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8
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Dejos C, Gkika D, Cantelmo AR. The Two-Way Relationship Between Calcium and Metabolism in Cancer. Front Cell Dev Biol 2020; 8:573747. [PMID: 33282859 PMCID: PMC7691323 DOI: 10.3389/fcell.2020.573747] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 10/12/2020] [Indexed: 12/14/2022] Open
Abstract
Calcium ion (Ca2+) signaling is critical to many physiological processes, and its kinetics and subcellular localization are tightly regulated in all cell types. All Ca2+ flux perturbations impact cell function and may contribute to various diseases, including cancer. Several modulators of Ca2+ signaling are attractive pharmacological targets due to their accessibility at the plasma membrane. Despite this, the number of specific inhibitors is still limited, and to date there are no anticancer drugs in the clinic that target Ca2+ signaling. Ca2+ dynamics are impacted, in part, by modifications of cellular metabolic pathways. Conversely, it is well established that Ca2+ regulates cellular bioenergetics by allosterically activating key metabolic enzymes and metabolite shuttles or indirectly by modulating signaling cascades. A coordinated interplay between Ca2+ and metabolism is essential in maintaining cellular homeostasis. In this review, we provide a snapshot of the reciprocal interaction between Ca2+ and metabolism and discuss the potential consequences of this interplay in cancer cells. We highlight the contribution of Ca2+ to the metabolic reprogramming observed in cancer. We also describe how the metabolic adaptation of cancer cells influences this crosstalk to regulate protumorigenic signaling pathways. We suggest that the dual targeting of these processes might provide unprecedented opportunities for anticancer strategies. Interestingly, promising evidence for the synergistic effects of antimetabolites and Ca2+-modulating agents is emerging.
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Affiliation(s)
- Camille Dejos
- Univ. Lille, Inserm, U1003 - PHYCEL - Physiologie Cellulaire, Lille, France
| | - Dimitra Gkika
- Univ. Lille, CNRS, INSERM, CHU Lille, Centre Oscar Lambret, UMR 9020-UMR 1277-Canther-Cancer Heterogeneity, Plasticity and Resistance to Therapies, Lille, France.,Institut Universitaire de France (IUF), Paris, France
| | - Anna Rita Cantelmo
- Univ. Lille, Inserm, U1003 - PHYCEL - Physiologie Cellulaire, Lille, France
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Maria Z, Campolo AR, Scherlag BJ, Ritchey JW, Lacombe VA. Insulin Treatment Reduces Susceptibility to Atrial Fibrillation in Type 1 Diabetic Mice. Front Cardiovasc Med 2020; 7:134. [PMID: 32903422 PMCID: PMC7434932 DOI: 10.3389/fcvm.2020.00134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 06/30/2020] [Indexed: 12/19/2022] Open
Abstract
Diabetes has been identified as an independent risk factor for atrial fibrillation (AF), the most common chronic cardiac arrhythmia. Whether or not glucose and insulin disturbances observed during diabetes enhance arrhythmogenicity of the atria, potentially leading to AF, is not well-known. We hypothesized that insulin deficiency and impaired glucose transport provide a metabolic substrate for the development and maintenance of AF during diabetes. Transesophageal atrial pacing was used to induce AF in healthy, streptozotocin-induced insulin-deficient type 1 diabetic, and insulin-treated diabetic mice. Translocation of insulin-sensitive glucose transporters (GLUTs) to the atrial cell surface was measured using a biotinylated photolabeling assay in the perfused heart. Fibrosis and glycogen accumulation in the atrium were measured using histological analysis. Diabetic mice displayed mild hyperglycemia, increased duration and frequency of AF episodes vs. age-matched controls (e.g., AF duration: 19.7 ± 6.8 s vs. 1.8 ± 1.1 s, respectively, p = 0.032), whereas insulin-treated diabetic animals did not. The translocation of insulin-sensitive GLUT-4 and -8 to the atrial cell surface was significantly downregulated in the diabetic mice (by 67 and 79%, respectively; p ≤ 0.001), and rescued by insulin treatment. We did not observe fibrosis or glycogen accumulation in the atria of diabetic mice. Therefore, these data suggest that insulin and glucose disturbances were sufficient to induce AF susceptibility during mild diabetes.
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Affiliation(s)
- Zahra Maria
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States
- Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Allison R. Campolo
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States
- Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Benjamin J. Scherlag
- Department of Internal Medicine, University of Oklahoma College of Medicine, Oklahoma City, OK, United States
| | - Jerry W. Ritchey
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK, United States
| | - Véronique A. Lacombe
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States
- Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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10
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Ren Y, Ribas HT, Heath K, Wu S, Ren J, Shriwas P, Chen X, Johnson ME, Cheng X, Burdette JE, Kinghorn AD. Na +/K +-ATPase-Targeted Cytotoxicity of (+)-Digoxin and Several Semisynthetic Derivatives. JOURNAL OF NATURAL PRODUCTS 2020; 83:638-648. [PMID: 32096998 PMCID: PMC7243443 DOI: 10.1021/acs.jnatprod.9b01060] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
(+)-Digoxin (1) is a well-known cardiac glycoside long used to treat congestive heart failure and found more recently to show anticancer activity. Several known cardenolides (2-5) and two new analogues, (+)-8(9)-β-anhydrodigoxigenin (6) and (+)-17-epi-20,22-dihydro-21α-hydroxydigoxin (7), were synthesized from 1 and evaluated for their cytotoxicity toward a small panel of human cancer cell lines. A preliminary structure-activity relationship investigation conducted indicated that the C-12 and C-14 hydroxy groups and the C-17 unsaturated lactone unit are important for 1 to mediate its cytotoxicity toward human cancer cells, but the C-3 glycosyl residue seems to be less critical for such an effect. Molecular docking profiles showed that the cytotoxic 1 and the noncytotoxic derivative 7 bind differentially to Na+/K+-ATPase. The HO-12β, HO-14β, and HO-3'aα hydroxy groups of (+)-digoxin (1) may form hydrogen bonds with the side-chains of Asp121 and Asn122, Thr797, and Arg880 of Na+/K+-ATPase, respectively, but the altered lactone unit of 7 results in a rotation of its steroid core, which depotentiates the binding between this compound and Na+/K+-ATPase. Thus, 1 was found to inhibit Na+/K+-ATPase, but 7 did not. In addition, the cytotoxic 1 did not affect glucose uptake in human cancer cells, indicating that this cardiac glycoside mediates its cytotoxicity by targeting Na+/K+-ATPase but not by interacting with glucose transporters.
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Affiliation(s)
- Yulin Ren
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210, United States
| | - Hennrique T. Ribas
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210, United States
| | - Kimberly Heath
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Sijin Wu
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210, United States
| | - Jinhong Ren
- Center for Biomolecular Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Pratik Shriwas
- Department of Biological Sciences, Edison Biotechnology Institute, and Molecular and Cellular Biology Program, Ohio University, Athens, OH 45701, United States
| | - Xiaozhuo Chen
- Department of Biological Sciences, Edison Biotechnology Institute, Molecular and Cellular Biology Program, and Department of Biomedical Sciences, Ohio University, Athens, OH 45701, United States
| | - Michael E. Johnson
- Department of Pharmaceutical Sciences and Center for Biomolecular Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Xiaolin Cheng
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210, United States
| | - Joanna E. Burdette
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
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11
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Zheng X, Arias EB, Qi NR, Saunders TL, Cartee GD. In vivo glucoregulation and tissue-specific glucose uptake in female Akt substrate 160 kDa knockout rats. PLoS One 2020; 15:e0223340. [PMID: 32053588 PMCID: PMC7018090 DOI: 10.1371/journal.pone.0223340] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/26/2020] [Indexed: 01/31/2023] Open
Abstract
The Rab GTPase activating protein known as Akt substrate of 160 kDa (AS160 or TBC1D4) regulates insulin-stimulated glucose uptake in skeletal muscle, the heart, and white adipose tissue (WAT). A novel rat AS160-knockout (AS160-KO) was created with CRISPR/Cas9 technology. Because female AS160-KO versus wild type (WT) rats had not been previously evaluated, the primary objective of this study was to compare female AS160-KO rats with WT controls for multiple, important metabolism-related endpoints. Body mass and composition, physical activity, and energy expenditure were not different between genotypes. AS160-KO versus WT rats were glucose intolerant based on an oral glucose tolerance test (P<0.001) and insulin resistant based on a hyperinsulinemic-euglycemic clamp (HEC; P<0.001). Tissue glucose uptake during the HEC of female AS160-KO versus WT rats was: 1) significantly lower in epitrochlearis (P<0.05) and extensor digitorum longus (EDL; P<0.01) muscles of AS160-KO compared to WT rats; 2) not different in soleus, gastrocnemius or WAT; and 3) ~3-fold greater in the heart (P<0.05). GLUT4 protein content was reduced in AS160-KO versus WT rats in the epitrochlearis (P<0.05), EDL (P<0.05), gastrocnemius (P<0.05), soleus (P<0.05), WAT (P<0.05), and the heart (P<0.005). Insulin-stimulated glucose uptake by isolated epitrochlearis and soleus muscles was lower (P<0.001) in AS160-KO versus WT rats. Akt phosphorylation of insulin-stimulated tissues was not different between the genotypes. A secondary objective was to probe processes that might account for the genotype-related increase in myocardial glucose uptake, including glucose transporter protein abundance (GLUT1, GLUT4, GLUT8, SGLT1), hexokinase II protein abundance, and stimulation of the AMP-activated protein kinase (AMPK) pathway. None of these parameters differed between genotypes. Metabolic phenotyping in the current study revealed AS160 deficiency produced a profound glucoregulatory phenotype in female AS160-KO rats that was strikingly similar to the results previously reported in male AS160-KO rats.
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Affiliation(s)
- Xiaohua Zheng
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Edward B. Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Nathan R. Qi
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States of America
| | - Thomas L. Saunders
- Transgenic Animal Model Core, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Gregory D. Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States of America
- Division of Genetic Medicine Genetics, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States of America
- Institute of Gerontology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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12
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Arias EB, Zheng X, Agrawal S, Cartee GD. Whole body glucoregulation and tissue-specific glucose uptake in a novel Akt substrate of 160 kDa knockout rat model. PLoS One 2019; 14:e0216236. [PMID: 31034517 PMCID: PMC6488193 DOI: 10.1371/journal.pone.0216236] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/16/2019] [Indexed: 11/26/2022] Open
Abstract
Akt substrate of 160 kDa (also called AS160 or TBC1D4) is a Rab GTPase activating protein and key regulator of insulin-stimulated glucose uptake which is expressed by multiple tissues, including skeletal muscle, white adipose tissue (WAT) and the heart. This study introduces a novel rat AS160-knockout (AS160-KO) model that was created using CRISPR/Cas9 technology. We compared male AS160-KO versus wildtype (WT) rats for numerous metabolism-related endpoints. Body mass, body composition, energy expenditure and physical activity did not differ between genotypes. Oral glucose intolerance was detected in AS160-KO versus WT rats (P<0.005). A hyperinsulinemic-euglycemic clamp (HEC) revealed insulin resistance for glucose infusion rate (P<0.05) with unaltered hepatic glucose production in AS160-KO versus WT rats. Genotype-effects on glucose uptake during the HEC: 1) was significantly lower in epitrochlearis (P<0.01) and extensor digitorum longus (P<0.05) of AS160-KO versus WT rats, and tended to be lower for AS160-KO versus WT rats in the soleus (P<0.06) and gastrocnemius (P<0.08); 2) tended to be greater for AS160-KO versus WT rats in white adipose tissue (P = 0.09); and 3) was significantly greater in the heart (P<0.005) of AS160-KO versus WT rats. GLUT4 protein abundance was significantly lower for AS160-KO versus WT rats in each tissue analyzed (P<0.01–0.001) except the gastrocnemius. Ex vivo insulin-stimulated glucose uptake was significantly lower (P<0.001) for AS160-KO versus WT rats in isolated epitrochlearis or soleus. Insulin-stimulated Akt phosphorylation (in vivo or ex vivo) did not differ between genotypes for any tissue tested. Ex vivo AICAR-stimulated glucose uptake by isolated epitrochlearis was significantly lower for AS160-KO versus WT rats (P<0.01) without genotype-induced alteration in AMP-activated protein phosphorylation. This unique AS160-KO rat model, which elucidated striking genotype-related modifications in glucoregulation, will enable future research aimed at understanding AS160’s roles in numerous physiological processes in response to various interventions (e.g., diet and/or exercise).
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Affiliation(s)
- Edward B. Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Xiaohua Zheng
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Swati Agrawal
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Gregory D. Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Institute of Gerontology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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13
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Shoop S, Maria Z, Campolo A, Rashdan N, Martin D, Lovern P, Lacombe VA. Glial Growth Factor 2 Regulates Glucose Transport in Healthy Cardiac Myocytes and During Myocardial Infarction via an Akt-Dependent Pathway. Front Physiol 2019; 10:189. [PMID: 30971932 PMCID: PMC6445869 DOI: 10.3389/fphys.2019.00189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 02/14/2019] [Indexed: 12/23/2022] Open
Abstract
Neuregulin (NRG), a paracrine factor in myocytes, promotes cardiac development via the ErbB receptors. NRG-1β also improves cardiac function and cell survival after myocardial infarction (MI), although the mechanisms underlying these cardioprotective effects are not well elucidated. Increased glucose uptake has been shown to be cardio-protective during MI. We hypothesized that treatment with a recombinant version of NRG-1β, glial growth factor 2 (GGF2), will enhance glucose transport in the healthy myocardium and during MI. Cardiac myocytes were isolated from MI and healthy adult rats, and subsequently incubated with or without insulin or GGF2. Glucose uptake was measured using a fluorescent D-glucose analog. The translocation of glucose transporter (GLUT) 4 to the cell surface, the rate-limiting step in glucose uptake, was measured using a photolabeled biotinylation assay in isolated myocytes. Similar to insulin, acute in vitro GGF2 treatment increased glucose uptake in healthy cardiac myocytes (by 40 and 49%, respectively, P = 0.002). GGF2 treatment also increased GLUT4 translocation in healthy myocytes by 184% (P < 0.01), while ErbB 2/4 receptor blockade (by afatinib) abolished these effects. In addition, GGF2 treatment enhanced Akt phosphorylation (at both threonine and serine sites, by 75 and 139%, respectively, P = 0.029 and P = 0.01), which was blunted by ErbB 2/4 receptor blockade. GGF2 treatment increased the phosphorylation of AS160 (an Akt effector) by 72% (P < 0.05), as well as the phosphorylation of PDK-1 and PKC (by 118 and 92%, respectively, P < 0.05). During MI, cardiac GLUT4 translocation was downregulated by 44% (P = 0.004) and was partially rescued by both in vitro insulin and GGF2 treatment. Our data demonstrate that acute GGF2 treatment increased glucose transport in cardiac myocytes by activating the ErbB 2/4 receptors and subsequent key downstream effectors (i.e., PDK-1, Akt, AS160, and PKC). These findings highlight novel mechanisms of action of GGF2, which warrant further investigation in patients with heart failure.
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Affiliation(s)
- Shanell Shoop
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States.,Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, United States
| | - Zahra Maria
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma, Oklahoma City, OK, United States
| | - Allison Campolo
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma, Oklahoma City, OK, United States
| | - Nabil Rashdan
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Dominic Martin
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, United States
| | - Pamela Lovern
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Véronique A Lacombe
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, United States.,Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma, Oklahoma City, OK, United States
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14
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Parriman M, Campolo A, Waller AP, Lacombe VA. Adverse Metabolic Effects of Diltiazem Treatment During Diabetic Cardiomyopathy. J Cardiovasc Pharmacol Ther 2018; 24:193-203. [PMID: 30458627 DOI: 10.1177/1074248418808392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Diabetes is a global epidemic disease, which leads to multiorgan dysfunction, including heart disease. Diabetes results from the limited absorption of glucose into insulin-sensitive tissues. The heart is one of the main organs to utilize glucose as an energy substrate. Glucose uptake into striated muscle is regulated by a family of membrane proteins called glucose transporters (GLUTs). Although calcium channel blockers, including diltiazem, are widely prescribed drugs for cardiovascular diseases, including in patients with diabetes, their pharmacological effects on glucose metabolism are somewhat controversial. We hypothesized that diltiazem treatment will exhibit detrimental effects on whole body glucose homeostasis and glucose transport in the striated muscle of patients with diabetes. Healthy and streptozotocin-treated rats were randomly assigned to receive diltiazem treatment or a placebo for 8 weeks. Blood glucose was significantly increased in the untreated diabetic groups, which worsened after diltiazem treatment. Diabetes decreased protein content of both GLUT4 (the predominate insulin-sensitive glucose transporter) and AS160 (Akt Substrate at 160 kDa, the downstream protein in the signaling cascade that regulates GLUT4 trafficking) in striated muscle of diabetic rats, with a more pronounced alteration after diltiazem treatment. We additionally reported that diabetic rodents displayed marked systolic dysfunction, which was not rescued by diltiazem treatment. In conclusion, diltiazem treatment worsened the effects of diabetes-induced hyperglycemia and diabetes-induced alterations in the regulation of glucose transport in striated muscle.
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Affiliation(s)
- Matt Parriman
- College of Pharmacy, The Ohio State University, OH, USA
| | - Allison Campolo
- Department of Physiological Sciences, Oklahoma State University, OK, USA
| | | | - Véronique A Lacombe
- College of Pharmacy, The Ohio State University, OH, USA.,Department of Physiological Sciences, Oklahoma State University, OK, USA
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15
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Zhao P, Ming Q, Qiu J, Tian D, Liu J, Shen J, Liu QH, Yang X. Ethanolic Extract of Folium Sennae Mediates the Glucose Uptake of L6 Cells by GLUT4 and Ca 2. Molecules 2018; 23:molecules23112934. [PMID: 30424024 PMCID: PMC6278344 DOI: 10.3390/molecules23112934] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/02/2018] [Accepted: 11/08/2018] [Indexed: 02/06/2023] Open
Abstract
In today’s world, diabetes mellitus (DM) is on the rise, especially type 2 diabetes mellitus (T2DM), which is characterized by insulin resistance. T2DM has high morbidity, and therapies with natural products have attracted much attention in the recent past. In this paper, we aimed to study the hypoglycemic effect and the mechanism of an ethanolic extract of Folium Sennae (FSE) on L6 cells. The glucose uptake of L6 cells was investigated using a glucose assay kit. We studied glucose transporter 4 (GLUT4) expression and AMP-activated protein kinase (AMPK), protein kinase B (PKB/Akt), and protein kinase C (PKC) phosphorylation levels using western blot analysis. GLUT4 trafficking and intracellular Ca2+ levels were monitored by laser confocal microscopy in L6 cells stably expressing IRAP-mOrange. GLUT4 fusion with plasma membrane (PM) was observed by myc-GLUT4-mOrange. FSE stimulated glucose uptake; GLUT4 expression and translocation; PM fusion; intracellular Ca2+ elevation; and the phosphorylation of AMPK, Akt, and PKC in L6 cells. GLUT4 translocation was weakened by the AMPK inhibitor compound C, PI3K inhibitor Wortmannin, PKC inhibitor Gö6983, G protein inhibitor PTX/Gallein, and PLC inhibitor U73122. Similarly, in addition to PTX/Gallein and U73122, the IP3R inhibitor 2-APB and a 0 mM Ca2+-EGTA solution partially inhibited the elevation of intracellular Ca2+ levels. BAPTA-AM had a significant inhibitory effect on FSE-mediated GLUT4 activities. In summary, FSE regulates GLUT4 expression and translocation by activating the AMPK, PI3K/Akt, and G protein–PLC–PKC pathways. FSE causes increasing Ca2+ concentration to complete the fusion of GLUT4 vesicles with PM, allowing glucose uptake. Therefore, FSE may be a potential drug for improving T2DM.
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Affiliation(s)
- Ping Zhao
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
- National Demonstration Center for Experimental Ethnopharmacology Education, South-Central University for Nationalities, Wuhan 430074, China.
| | - Qian Ming
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Junying Qiu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Di Tian
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Jia Liu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Jinhua Shen
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Qing-Hua Liu
- Institute for Medical Biology & Hubei Provincial Key Laboratory for Protection and Application of Special Plants in the Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Xinzhou Yang
- National Demonstration Center for Experimental Ethnopharmacology Education, South-Central University for Nationalities, Wuhan 430074, China.
- School of Pharmaceutical Sciences, South-Central University for Nationalities, 182 Min-Zu Road, Wuhan 430074, China.
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16
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Hamilton S, Terentyev D. Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity. Front Physiol 2018. [PMID: 30425651 DOI: 10.3389/fphys.2018.01517, 10.3389/fpls.2018.01517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca2+ transport protein complexes including plasmalemmal L-type Ca2+ channels (LTCC), Na+-Ca2+ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca2+-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca2+ release channels. Here we provide an overview of changes in Ca2+ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca2+ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
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17
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Hamilton S, Terentyev D. Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity. Front Physiol 2018; 9:1517. [PMID: 30425651 PMCID: PMC6218530 DOI: 10.3389/fphys.2018.01517] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/09/2018] [Indexed: 12/28/2022] Open
Abstract
A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca2+ transport protein complexes including plasmalemmal L-type Ca2+ channels (LTCC), Na+-Ca2+ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca2+-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca2+ release channels. Here we provide an overview of changes in Ca2+ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca2+ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
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18
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Zheng J, Cheng J, Zheng S, Zhang L, Guo X, Zhang J, Xiao X. Physical Exercise and Its Protective Effects on Diabetic Cardiomyopathy: What Is the Evidence? Front Endocrinol (Lausanne) 2018; 9:729. [PMID: 30559720 PMCID: PMC6286969 DOI: 10.3389/fendo.2018.00729] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 11/16/2018] [Indexed: 12/25/2022] Open
Abstract
As one of the most serious complications of diabetes, diabetic cardiomyopathy (DCM) imposes a huge burden on individuals and society, and represents a major public health problem. It has long been recognized that physical exercise has important health benefits for patients with type 2 diabetes, and regular physical exercise can delay or prevent the complications of diabetes. Current studies show that physical exercise has been regarded as an importantly non-pharmacological treatment for diabetes and DCM, with high efficacy and low adverse events. It can inhibit the pathological processes of myocardial apoptosis, myocardial fibrosis, and myocardial microvascular diseases through improving myocardial metabolism, enhancing the regulation of Ca2+, and protecting the function of mitochondria. Eventually, it can alleviate the occurrence and development of diabetic complications. Describing the mechanisms of physical exercise on DCM may provide a new theory for alleviating, or even reversing the development of DCM, and prevent it from developing to heart failure.
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Affiliation(s)
- Jia Zheng
- Key Laboratory of Endocrinology, Department of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- Department of Endocrinology, Peking University First Hospital, Beijing, China
| | - Jing Cheng
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Shandong University Qilu Hospital, Shandong, China
| | - Sheng Zheng
- Department of Orthopedics, XiangYang Hospital of Traditional Chinese Medicine, Hubei, China
| | - Ling Zhang
- Department of Endocrinology, Peking University First Hospital, Beijing, China
| | - Xiaohui Guo
- Department of Endocrinology, Peking University First Hospital, Beijing, China
| | - Junqing Zhang
- Department of Endocrinology, Peking University First Hospital, Beijing, China
- Junqing Zhang
| | - Xinhua Xiao
- Key Laboratory of Endocrinology, Department of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- *Correspondence: Xinhua Xiao
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19
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Maria Z, Campolo AR, Scherlag BJ, Ritchey JW, Lacombe VA. Dysregulation of insulin-sensitive glucose transporters during insulin resistance-induced atrial fibrillation. Biochim Biophys Acta Mol Basis Dis 2017; 1864:987-996. [PMID: 29291943 DOI: 10.1016/j.bbadis.2017.12.038] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/29/2017] [Accepted: 12/23/2017] [Indexed: 11/18/2022]
Abstract
Diabetes has been identified as major risk factor for atrial fibrillation (AF). Although glucose and insulin disturbances during diabetes may affect atrial function, little is known about the potential pathogenic role of glucose metabolism during AF. Glucose transport into the cell via glucose transporters (GLUTs) is the rate-limiting step of glucose utilization. Although GLUT4 is the major isoform, GLUT8 has emerged as a novel insulin-sensitive cardiac isoform. We hypothesized that atrial glucose homeostasis will be impaired during insulin resistance-induced AF. AF was induced by transesophageal atrial pacing in healthy mice and following a long-term high-fat-diet-induced insulin resistance. Active cell surface GLUT content was measured using the biotinylated photolabeling assay in the intact perfused heart. Atrial fibrosis, advanced glycation end products (AGEs) and glycogen were measured in the atria using histological analyses. Animals fed a high-fat-diet were obese and mildly hyperglycemic, and developed insulin resistance compared to controls. Insulin-resistant (IR) animals demonstrated an increased vulnerability to induced AF, as well as spontaneous AF. Insulin-stimulated translocation of GLUT4 and GLUT8 was down-regulated in the atria of IR animals, as well as their total protein expression. We also reported the absence of fibrosis, glycogen and AGE accumulation in the atria of IR animals. In the absence of structural remodeling and atrial fibrosis, these data suggest that insulin signaling dysregulation, resulting in impaired glucose transport in the atria, could provide a metabolic arrhythmogenic substrate and be a novel early pathogenic factor of AF.
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Affiliation(s)
- Zahra Maria
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, USA; Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Allison R Campolo
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, USA; Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Benjamin J Scherlag
- Department of Internal Medicine, University of Oklahoma, Oklahoma City, OK, USA
| | - Jerry W Ritchey
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK, USA
| | - Véronique A Lacombe
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, USA; Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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Quantification of Cell-Surface Glucose Transporters in the Heart Using a Biotinylated Photolabeling Assay. Methods Mol Biol 2017. [PMID: 29218529 DOI: 10.1007/978-1-4939-7507-5_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The biotinylated photolabeling assay enables quantification of cell-surface glucose transporters (GLUTs). This technique has been successfully applied to quantify the cell-surface GLUT protein content in striated muscles and adipose tissue, as a means to evaluate GLUT trafficking. Here, we describe the detailed method of quantifying the cell-surface content of several GLUT isoforms (1, 4, 8, and 12) in isolated cardiac myocytes, as well as in the intact perfused atria and ventricle.
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von Lewinski D, Kolesnik E, Wallner M, Resl M, Sourij H. New Antihyperglycemic Drugs and Heart Failure: Synopsis of Basic and Clinical Data. BIOMED RESEARCH INTERNATIONAL 2017; 2017:1253425. [PMID: 28894748 PMCID: PMC5574229 DOI: 10.1155/2017/1253425] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 07/12/2017] [Indexed: 12/24/2022]
Abstract
The assessment of the cardiovascular safety profile of any newly developed antihyperglycemic drug is mandatory before registration, as a meta-analysis raised alarm describing a significant increase in myocardial infarction with the thiazolidinedione rosiglitazone. The first results from completed cardiovascular outcome trials are already available: TECOS, SAVOR-TIMI, and EXAMINE investigated dipeptidyl peptidase 4 (DPP-4) inhibitors, ELIXA, LEADER, and SUSTAIN-6 investigated glucagon-like peptide 1 (GLP-1) receptor agonists, and EMPA-REG OUTCOME and CANVAS investigated sodium-dependent glucose transporter 2 (SGLT-2) inhibitors. LEADER, SUSTAIN-6, EMPA-REG OUTCOME, and CANVAS showed potential beneficial results, while the SAVOR-TIMI trial had an increased rate of hospitalization for heart failure. Meanwhile, the same drugs are investigated in preclinical experiments mainly using various animal models, which aim to find interactions and elucidate the underlying downstream mechanisms between the antihyperglycemic drugs and the cardiovascular system. Yet the direct link for observed effects, especially for DPP-4 and SGLT-2 inhibitors, is still unknown. Further inquiry into these mechanisms is crucial for the interpretation of the clinical trials' outcome and, vice versa, the clinical trials provide hints for an involvement of the cardiovascular system. The synopsis of preclinical and clinical data is essential for a detailed understanding of benefits and risks of new antihyperglycemic drugs.
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Affiliation(s)
- Dirk von Lewinski
- Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
| | - Ewald Kolesnik
- Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
| | - Markus Wallner
- Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
- Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Michael Resl
- Department of Endocrinology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Department of Internal Medicine, Hospital Barmherzige Brüder Linz, Seilerstätte 2, 4021 Linz, Austria
| | - Harald Sourij
- Department of Endocrinology and Diabetology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
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Guo H, Cao A, Chu S, Wang Y, Zang Y, Mao X, Wang H, Wang Y, Liu C, Zhang X, Peng W. Astragaloside IV Attenuates Podocyte Apoptosis Mediated by Endoplasmic Reticulum Stress through Upregulating Sarco/Endoplasmic Reticulum Ca 2+-ATPase 2 Expression in Diabetic Nephropathy. Front Pharmacol 2016; 7:500. [PMID: 28066247 PMCID: PMC5174081 DOI: 10.3389/fphar.2016.00500] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 12/05/2016] [Indexed: 12/18/2022] Open
Abstract
Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) plays a central role in the pathogenesis of diabetes. This protein has been recognized as a potential target for diabetic therapy. In this study, we identified astragaloside IV (AS-IV) as a potent modulator of SERCA inhibiting renal injury in diabetic status. Increasing doses of AS-IV (2, 6, and 18 mg kg-1 day-1) were administered intragastrically to db/db mice for 8 weeks. Biochemical and histopathological approaches were conducted to evaluate the therapeutic effects of AS-IV. Cultured mouse podocytes were used to further explore the underlying mechanism in vitro. AS-IV dose-dependently increased SERCA activity and SERCA2 expression, and suppressed ER stress-mediated and mitochondria-mediated apoptosis in db/db mouse kidney. AS-IV also normalized glucose tolerance and insulin sensitivity, improved renal function, and ameliorated glomerulosclerosis and renal inflammation in db/db mice. In palmitate stimulated podocytes, AS-IV markedly improved inhibitions of SERCA activity and SERCA2 expression, restored intracellular Ca2+ homeostasis, and attenuated podocyte apoptosis in a dose-dependent manner with a concomitant abrogation of ER stress as evidenced by the downregulation of GRP78, cleaved ATF6, phospho-IRE1α and phospho-PERK, and the inactivation of both ER stress-mediated and mitochondria-mediated apoptotic pathways. Furthermore, SERCA2b knockdown eliminated the effect of AS-IV on ER stress and ER stress-mediated apoptotic pathway, whereas its overexpression exhibited an anti-apoptotic effect. Our data obtained from in vivo and in vitro studies demonstrate that AS-IV attenuates renal injury in diabetes subsequent to inhibiting ER stress-induced podocyte apoptosis through restoring SERCA activity and SERCA2 expression.
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Affiliation(s)
- Hengjiang Guo
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Aili Cao
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Shuang Chu
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Yi Wang
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Yingjun Zang
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Xiaodong Mao
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Hao Wang
- Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Yunman Wang
- Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Cheng Liu
- Experimental Research Center, Putuo Hospital, Shanghai University of Traditional Chinese Medicine Shanghai, China
| | - Xuemei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University Shanghai, China
| | - Wen Peng
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese MedicineShanghai, China; Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese MedicineShanghai, China
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Diabetes Alters the Expression and Translocation of the Insulin-Sensitive Glucose Transporters 4 and 8 in the Atria. PLoS One 2015; 10:e0146033. [PMID: 26720696 PMCID: PMC4697822 DOI: 10.1371/journal.pone.0146033] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/12/2015] [Indexed: 01/14/2023] Open
Abstract
Although diabetes has been identified as a major risk factor for atrial fibrillation, little is known about glucose metabolism in the healthy and diabetic atria. Glucose transport into the cell, the rate-limiting step of glucose utilization, is regulated by the Glucose Transporters (GLUTs). Although GLUT4 is the major isoform in the heart, GLUT8 has recently emerged as a novel cardiac isoform. We hypothesized that GLUT-4 and -8 translocation to the atrial cell surface will be regulated by insulin and impaired during insulin-dependent diabetes. GLUT protein content was measured by Western blotting in healthy cardiac myocytes and type 1 (streptozotocin-induced, T1Dx) diabetic rodents. Active cell surface GLUT content was measured using a biotinylated photolabeled assay in the perfused heart. In the healthy atria, insulin stimulation increased both GLUT-4 and -8 translocation to the cell surface (by 100% and 240%, respectively, P<0.05). Upon insulin stimulation, we reported an increase in Akt (Th308 and s473 sites) and AS160 phosphorylation, which was positively (P<0.05) correlated with GLUT4 protein content in the healthy atria. During diabetes, active cell surface GLUT-4 and -8 content was downregulated in the atria (by 70% and 90%, respectively, P<0.05). Akt and AS160 phosphorylation was not impaired in the diabetic atria, suggesting the presence of an intact insulin signaling pathway. This was confirmed by the rescued translocation of GLUT-4 and -8 to the atrial cell surface upon insulin stimulation in the atria of type 1 diabetic subjects. In conclusion, our data suggest that: 1) both GLUT-4 and -8 are insulin-sensitive in the healthy atria through an Akt/AS160 dependent pathway; 2) GLUT-4 and -8 trafficking is impaired in the diabetic atria and rescued by insulin treatment. Alterations in atrial glucose transport may induce perturbations in energy production, which may provide a metabolic substrate for atrial fibrillation during diabetes.
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Jackson EE, Rendina-Ruedy E, Smith BJ, Lacombe VA. Loss of Toll-Like Receptor 4 Function Partially Protects against Peripheral and Cardiac Glucose Metabolic Derangements During a Long-Term High-Fat Diet. PLoS One 2015; 10:e0142077. [PMID: 26539824 PMCID: PMC4634760 DOI: 10.1371/journal.pone.0142077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023] Open
Abstract
Diabetes is a chronic inflammatory disease that carries a high risk of cardiovascular disease. However, the pathophysiological link between these disorders is not well known. We hypothesize that TLR4 signaling mediates high fat diet (HFD)-induced peripheral and cardiac glucose metabolic derangements. Mice with a loss-of-function mutation in TLR4 (C3H/HeJ) and age-matched control (C57BL/6) mice were fed either a high-fat diet or normal diet for 16 weeks. Glucose tolerance and plasma insulin were measured. Protein expression of glucose transporters (GLUT), AKT (phosphorylated and total), and proinflammatory cytokines (IL-6, TNF-α and SOCS-3) were quantified in the heart using Western Blotting. Both groups fed a long-term HFD had increased body weight, blood glucose and insulin levels, as well as impaired glucose tolerance compared to mice fed a normal diet. TLR4-mutant mice were partially protected against long-term HFD-induced insulin resistance. In control mice, feeding a HFD decreased cardiac crude membrane GLUT4 protein content, which was partially rescued in TLR4-mutant mice. TLR4-mutant mice fed a HFD also had increased expression of GLUT8, a novel isoform, compared to mice fed a normal diet. GLUT8 content was positively correlated with SOCS-3 and IL-6 expression in the heart. No significant differences in cytokine expression were observed between groups, suggesting a lack of inflammation in the heart following a HFD. Loss of TLR4 function partially restored a healthy metabolic phenotype, suggesting that TLR4 signaling is a key mechanism in HFD-induced peripheral and cardiac insulin resistance. Our data further suggest that TLR4 exerts its detrimental metabolic effects in the myocardium through a cytokine-independent pathway.
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Affiliation(s)
- Ellen E. Jackson
- Department of Physiological Sciences, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Elisabeth Rendina-Ruedy
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Brenda J. Smith
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Veronique A. Lacombe
- Department of Physiological Sciences, Oklahoma State University, Stillwater, Oklahoma, United States of America
- Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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