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Amelioration of Hepatic Steatosis by the Androgen Receptor Inhibitor EPI-001 in Mice and Human Hepatic Cells Is Associated with the Inhibition of CYP2E1. Int J Mol Sci 2022; 23:ijms232416063. [PMID: 36555703 PMCID: PMC9785868 DOI: 10.3390/ijms232416063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/05/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is recognized as a metabolic disease characterized by hepatic steatosis. Despite the growing burden of NAFLD, approved pharmacological treatment is lacking. As an inhibitor of androgen receptor (AR), EPI-001 is being explored for the treatment of prostate cancer. This study aimed to investigate the potential of EPI-001 for treating NAFLD in free fatty acids (FFAs)-induced human hepatic cells and high-fat-high-sugar (HFHS)-feeding mice. Our results showed that EPI-001 reduced lipid accumulation in hepatic cells and ameliorated hepatic steatosis in mouse livers. Further exploration suggested that the effect of EPI-001 was associated with CYP2E1-mediated reduction of reactive oxygen species (ROS). This provides encouraging evidence for further studies on EPI-001 therapy for NAFLD.
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2
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Karabulut Uzuncakmak S, Dirican E, Naldan ME, Kesmez Can F, Halıcı Z. Investigation of CYP2E1 and Caspase-3 Gene Expressions in COVID-19 patients. GENE REPORTS 2022; 26:101497. [PMID: 35071821 PMCID: PMC8760173 DOI: 10.1016/j.genrep.2022.101497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 12/29/2021] [Accepted: 01/10/2022] [Indexed: 11/27/2022]
Abstract
Background COVID-19 pandemic spread around the world like an infectious disease that presents waved effects on patients. Some patients needed ICU and respiratory support. Some patients only had flu-like symptoms. Cytokine storm and elevated ROS were serious problems for treatment. Apoptotic genes and CYP Family are part of these mechanisms. Aim In this study, our aim was to examine the gene expression CYP2E1 and Caspase-3 in patients with COVID-19 infection. Method 60 COVID-19(+) patients (ICU and non-ICU patients) and 30 healthy volunteers were enrolled to study. To measure the level of gene expression qPCR was used. The 2-ΔΔCt method was utilized to analyze gene expression. Results The expression of CYP2E1 and Caspase-3 genes showed a significant discrepancy between patients and healthy individuals. Caspase-3 expression increased (p=0,0041) but CYP2E1 expression decreased (p=0,0214) in COVID-19 patients compared to healthy individuals. Both levels of gene expression were lower in patients with affected lungs than patients with unaffected lungs (p<0,05). Laboratory findings including d-Dimer, LDH, platelet count, lymphocyte count were related to both gene expressions (p<0,05). We found no correlation between CYP2E1 and Caspase-3 expressions. Conclusion The expression of Caspase-3 demonstrated apoptotic situations of patients but was not related to the CYP2E1 expression level. CYP2E1 gene expression is an important actor to metabolize endogens and xenobiotics however, COVID-19 patients demonstrated decreased CYP2E1 expression. CYP2E1 and Caspase-3 gene expression levels may be used as a diagnostic tool for COVID-19 patients.
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Affiliation(s)
| | - E Dirican
- Health Services Vocational School, Bayburt University, Bayburt 69000, Turkey
| | - M E Naldan
- Department of Anesthesia, Regional Education and Research Hospital, Erzurum 25240, Turkey
| | - F Kesmez Can
- Faculty of Medicine, Department of Infectious and Clinical Microbiology Diseases, Atatürk University, Erzurum 25240, Turkey
| | - Z Halıcı
- Faculty of Medicine, Department of Pharmacology, Atatürk University, Erzurum 25240, Turkey
- Clinical Research, Development and Design Application and Research Center, Ataturk University, 25240 Erzurum, Turkey
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3
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Lamboley CR, Pearce L, Seng C, Meizoso-Huesca A, Singh DP, Frankish BP, Kaura V, Lo HP, Ferguson C, Allen PD, Hopkins PM, Parton RG, Murphy RM, van der Poel C, Barclay CJ, Launikonis BS. Ryanodine receptor leak triggers fiber Ca 2+ redistribution to preserve force and elevate basal metabolism in skeletal muscle. SCIENCE ADVANCES 2021; 7:eabi7166. [PMID: 34705503 PMCID: PMC8550231 DOI: 10.1126/sciadv.abi7166] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Muscle contraction depends on tightly regulated Ca2+ release. Aberrant Ca2+ leak through ryanodine receptor 1 (RyR1) on the sarcoplasmic reticulum (SR) membrane can lead to heatstroke and malignant hyperthermia (MH) susceptibility, as well as severe myopathy. However, the mechanism by which Ca2+ leak drives these pathologies is unknown. Here, we investigate the effects of four mouse genotypes with increasingly severe RyR1 leak in skeletal muscle fibers. We find that RyR1 Ca2+ leak initiates a cascade of events that cause precise redistribution of Ca2+ among the SR, cytoplasm, and mitochondria through altering the Ca2+ permeability of the transverse tubular system membrane. This redistribution of Ca2+ allows mice with moderate RyR1 leak to maintain normal function; however, severe RyR1 leak with RYR1 mutations reduces the capacity to generate force. Our results reveal the mechanism underlying force preservation, increased ATP metabolism, and susceptibility to MH in individuals with gain-of-function RYR1 mutations.
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Affiliation(s)
- Cedric R. Lamboley
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Luke Pearce
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Crystal Seng
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Aldo Meizoso-Huesca
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Daniel P. Singh
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Barnaby P. Frankish
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Vikas Kaura
- Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | - Harriet P. Lo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Charles Ferguson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Paul D. Allen
- Leeds Institute of Medical Research, University of Leeds, Leeds, UK
| | | | - Robert G. Parton
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD, Australia
| | - Robyn M. Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
- Department of Physiology Anatomy and Microbiology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Chris van der Poel
- Department of Physiology Anatomy and Microbiology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Christopher J. Barclay
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Bradley S. Launikonis
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Corresponding author.
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4
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Nelson ME, Parker BL, Burchfield JG, Hoffman NJ, Needham EJ, Cooke KC, Naim T, Sylow L, Ling NXY, Francis D, Norris DM, Chaudhuri R, Oakhill JS, Richter EA, Lynch GS, Stöckli J, James DE. Phosphoproteomics reveals conserved exercise-stimulated signaling and AMPK regulation of store-operated calcium entry. EMBO J 2019; 38:e102578. [PMID: 31381180 PMCID: PMC6912027 DOI: 10.15252/embj.2019102578] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/27/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
Exercise stimulates cellular and physiological adaptations that are associated with widespread health benefits. To uncover conserved protein phosphorylation events underlying this adaptive response, we performed mass spectrometry-based phosphoproteomic analyses of skeletal muscle from two widely used rodent models: treadmill running in mice and in situ muscle contraction in rats. We overlaid these phosphoproteomic signatures with cycling in humans to identify common cross-species phosphosite responses, as well as unique model-specific regulation. We identified > 22,000 phosphosites, revealing orthologous protein phosphorylation and overlapping signaling pathways regulated by exercise. This included two conserved phosphosites on stromal interaction molecule 1 (STIM1), which we validate as AMPK substrates. Furthermore, we demonstrate that AMPK-mediated phosphorylation of STIM1 negatively regulates store-operated calcium entry, and this is beneficial for exercise in Drosophila. This integrated cross-species resource of exercise-regulated signaling in human, mouse, and rat skeletal muscle has uncovered conserved networks and unraveled crosstalk between AMPK and intracellular calcium flux.
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Affiliation(s)
- Marin E Nelson
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Benjamin L Parker
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
- Present address:
Department of PhysiologyThe University of MelbourneMelbourneVic.Australia
| | - James G Burchfield
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Nolan J Hoffman
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
- Present address:
Exercise and Nutrition Research ProgramMary MacKillop Institute for Health ResearchAustralian Catholic UniversityMelbourneVic.Australia
| | - Elise J Needham
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Kristen C Cooke
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Timur Naim
- Centre for Muscle ResearchDepartment of PhysiologySchool of Biomedical SciencesThe University of MelbourneMelbourneVicAustralia
| | - Lykke Sylow
- Department of Nutrition, Exercise and SportsFaculty of ScienceThe University of CopenhagenCopenhagenDenmark
| | - Naomi XY Ling
- Metabolic Signalling LaboratorySt. Vincent's Institute of Medical ResearchMelbourneVic.Australia
| | - Deanne Francis
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Dougall M Norris
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Rima Chaudhuri
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Jonathan S Oakhill
- Metabolic Signalling LaboratorySt. Vincent's Institute of Medical ResearchMelbourneVic.Australia
- Exercise and Nutrition Research ProgramMary MacKillop Institute for Health ResearchAustralian Catholic UniversityMelbourneVic.Australia
| | - Erik A Richter
- Department of Nutrition, Exercise and SportsFaculty of ScienceThe University of CopenhagenCopenhagenDenmark
| | - Gordon S Lynch
- Centre for Muscle ResearchDepartment of PhysiologySchool of Biomedical SciencesThe University of MelbourneMelbourneVicAustralia
| | - Jacqueline Stöckli
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - David E James
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
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5
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Components of activation heat in skeletal muscle. J Muscle Res Cell Motil 2019; 42:1-16. [PMID: 31346851 DOI: 10.1007/s10974-019-09547-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/21/2019] [Indexed: 10/26/2022]
Abstract
Activation heat (qA) production by muscle is the thermal accompaniment of the release of Ca2+ from the sarcoplasmic reticulum (SR) into the cytoplasm, its interactions with regulatory proteins and other cytoplasmic Ca2+ buffers and its return to the SR. The contribution of different Ca2+-related reactions to qA is difficult to determine empirically and therefore, for this study, a mathematical model was developed to describe Ca2+ movements and accompanying thermal changes in muscle fibres in response to stimulation. The major sources of heat within a few milliseconds of the initiation of Ca2+ release are Ca2+ binding to Tn and Pv. Ca2+ binding to ATP produces a relatively small amount of heat. Ca2+ dissociation from ATP and Tn, with heat absorption, are of similar time course to the decline of force. In muscle lacking Pv (e.g. mouse soleus), Ca2+ is then rapidly pumped into the SR. In muscles with Pv, Ca2+ that dissociates from Tn and ATP binds to Pv and then dissociates slowly (over 10 s of seconds) and is then pumped into the SR; the net effect of these two processes is heat absorption. It is proposed that this underlies Hill's "negative delayed heat". After all the Ca2+ is returned to the SR, qA is proportional to the amount of Ca2+ released into the cytoplasm. In muscles with Pv this is 20-60 s after Ca2+ release; in muscles without Pv, all Ca2+ is returned to the SR soon after the end of force relaxation.
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6
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Abdelmegeed MA, Ha SK, Choi Y, Akbar M, Song BJ. Role of CYP2E1 in Mitochondrial Dysfunction and Hepatic Injury by Alcohol and Non-Alcoholic Substances. Curr Mol Pharmacol 2019; 10:207-225. [PMID: 26278393 DOI: 10.2174/1874467208666150817111114] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/07/2015] [Accepted: 08/07/2015] [Indexed: 12/17/2022]
Abstract
Alcoholic fatty liver disease (AFLD) and non-alcoholic fatty liver disease (NAFLD) are two pathological conditions that are spreading worldwide. Both conditions are remarkably similar with regard to the pathophysiological mechanism and progression despite different causes. Oxidative stressinduced mitochondrial dysfunction through post-translational protein modifications and/or mitochondrial DNA damage has been a major risk factor in both AFLD and NAFLD development and progression. Cytochrome P450-2E1 (CYP2E1), a known important inducer of oxidative radicals in the cells, has been reported to remarkably increase in both AFLD and NAFLD. Interestingly, CYP2E1 isoforms expressed in both endoplasmic reticulum (ER) and mitochondria, likely lead to the deleterious consequences in response to alcohol or in conditions of NAFLD after exposure to high fat diet (HFD) and in obesity and diabetes. Whether CYP2E1 in both ER and mitochondria work simultaneously or sequentially in various conditions and whether mitochondrial CYP2E1 may exert more pronounced effects on mitochondrial dysfunction in AFLD and NAFLD are unclear. The aims of this review are to briefly describe the role of CYP2E1 and resultant oxidative stress in promoting mitochondrial dysfunction and the development or progression of AFLD and NAFLD, to shed a light on the function of the mitochondrial CYP2E1 as compared with the ER-associated CYP2E1. We finally discuss translational research opportunities related to this field.
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Affiliation(s)
- Mohamed A Abdelmegeed
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, 9000 Rockville Pike, Bethesda, MD 20892. United States
| | - Seung-Kwon Ha
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane, Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD. United States
| | - Youngshim Choi
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane, Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD. United States
| | - Mohammed Akbar
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane, Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD. United States
| | - Byoung-Joon Song
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane, Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD. United States
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7
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Morales-Alamo D, Guerra B, Santana A, Martin-Rincon M, Gelabert-Rebato M, Dorado C, Calbet JAL. Skeletal Muscle Pyruvate Dehydrogenase Phosphorylation and Lactate Accumulation During Sprint Exercise in Normoxia and Severe Acute Hypoxia: Effects of Antioxidants. Front Physiol 2018; 9:188. [PMID: 29615918 PMCID: PMC5867337 DOI: 10.3389/fphys.2018.00188] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 02/23/2018] [Indexed: 12/30/2022] Open
Abstract
Compared to normoxia, during sprint exercise in severe acute hypoxia the glycolytic rate is increased leading to greater lactate accumulation, acidification, and oxidative stress. To determine the role played by pyruvate dehydrogenase (PDH) activation and reactive nitrogen and oxygen species (RNOS) in muscle lactate accumulation, nine volunteers performed a single 30-s sprint (Wingate test) on four occasions: two after the ingestion of placebo and another two following the intake of antioxidants, while breathing either hypoxic gas (PIO2 = 75 mmHg) or room air (PIO2 = 143 mmHg). Vastus lateralis muscle biopsies were obtained before, immediately after, 30 and 120 min post-sprint. Antioxidants reduced the glycolytic rate without altering performance or VO2. Immediately after the sprints, Ser293- and Ser300-PDH-E1α phosphorylations were reduced to similar levels in all conditions (~66 and 91%, respectively). However, 30 min into recovery Ser293-PDH-E1α phosphorylation reached pre-exercise values while Ser300-PDH-E1α was still reduced by 44%. Thirty minutes after the sprint Ser293-PDH-E1α phosphorylation was greater with antioxidants, resulting in 74% higher muscle lactate concentration. Changes in Ser293 and Ser300-PDH-E1α phosphorylation from pre to immediately after the sprints were linearly related after placebo (r = 0.74, P < 0.001; n = 18), but not after antioxidants ingestion (r = 0.35, P = 0.15). In summary, lactate accumulation during sprint exercise in severe acute hypoxia is not caused by a reduced activation of the PDH. The ingestion of antioxidants is associated with increased PDH re-phosphorylation and slower elimination of muscle lactate during the recovery period. Ser293 re-phosphorylates at a faster rate than Ser300-PDH-E1α during the recovery period, suggesting slightly different regulatory mechanisms.
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Affiliation(s)
- David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Borja Guerra
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain.,Clinical Genetics Unit, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Marcos Martin-Rincon
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Miriam Gelabert-Rebato
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Cecilia Dorado
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
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8
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Perni S, Close M, Franzini-Armstrong C. Design Principles of Reptilian Muscles: Calcium Cycling Strategies. Anat Rec (Hoboken) 2015; 299:352-60. [PMID: 26663776 DOI: 10.1002/ar.23302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 10/08/2015] [Accepted: 10/29/2015] [Indexed: 11/07/2022]
Abstract
The ultrastructure of the sarcoplasmic reticulum (SR) in skeletal muscles was compared among different reptile species (watersnake, boa constrictor, lizard, and turtle) and a mammal (mouse). Morphometric analysis demonstrates a pattern of increasing calsequestrin (CASQ) content in the lumen of SR from turtle to lizard, watersnake, and boa constrictor, and this content is in all cases higher than in mouse. In all reptiles sampled except turtle, CASQ is not confined to the junctional sarcoplasmic reticulum (jSR) cisternae as it is in other species. It instead fills the entire longitudinal (free) SR (fSR) regions, and in the extreme case of snakes, the shape of the SR is modified around the extra CASQ. We suggest that high CASQ content may represent an ATP-saving adaptation that permits relatively low metabolic rates during prolonged periods of fasting and inactivity, particularly in watersnake and boa constrictor.
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Affiliation(s)
- Stefano Perni
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Matthew Close
- Department of Biological Sciences, Williams Annex., Lehigh University, Bethlehem, Pennsylvania
| | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania
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9
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Dass S, Cochlin LE, Suttie JJ, Holloway CJ, Rider OJ, Carden L, Tyler DJ, Karamitsos TD, Clarke K, Neubauer S, Watkins H. Exacerbation of cardiac energetic impairment during exercise in hypertrophic cardiomyopathy: a potential mechanism for diastolic dysfunction. Eur Heart J 2015; 36:1547-54. [PMID: 25990345 DOI: 10.1093/eurheartj/ehv120] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 03/24/2015] [Indexed: 11/14/2022] Open
Abstract
AIMS Hypertrophic cardiomyopathy (HCM) is the commonest cause of sudden cardiac death in the young, with an excess of exercise-related deaths. The HCM sarcomere mutations increase the energy cost of contraction and impaired resting cardiac energetics has been documented by measurement of phosphocreatine/ATP (PCr/ATP) using (31)Phosphorus MR Spectroscopy ((31)P MRS). We hypothesized that cardiac energetics are further impaired acutely during exercise in HCM and that this would have important functional consequences. METHODS AND RESULTS (31)P MRS was performed in 35 HCM patients and 20 age- and gender-matched normal volunteers at rest and during leg exercise with 2.5 kg ankle weights. Peak left-ventricular filling rates (PFRs) and myocardial perfusion reserve (MPRI) were calculated during adenosine stress. Resting PCr/ATP was significantly reduced in HCM (HCM: 1.71 ± 0.35, normal 2.14 ± 0.35 P < 0.0001). During exercise, there was a further reduction in PCr/ATP in HCM (1.56 ± 0.29, P = 0.02 compared with rest) but not in normals (2.16 ± 0.26, P = 0.98 compared with rest). There was no correlation between PCr/ATP reduction and cardiac mass, wall thickness, MPRI, or late-gadolinium enhancement. PFR and PCr/ATP were significantly correlated at rest (r = 0.48, P = 0.02) and stress (r = 0.53, P = 0.01). CONCLUSION During exercise, the pre-existing energetic deficit in HCM is further exacerbated independent of hypertrophy, perfusion reserve, or degree of fibrosis. This is in keeping with the change at the myofilament level. We offer a potential explanation for exercise-related diastolic dysfunction in HCM.
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Affiliation(s)
- Sairia Dass
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Lowri E Cochlin
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Joseph J Suttie
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Cameron J Holloway
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Oliver J Rider
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Leah Carden
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Theodoros D Karamitsos
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Stefan Neubauer
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Anatomy and Genetics, Oxford University, Oxford, UK
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10
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ALVIM RAFAELO, CHEUHEN MARCELR, MACHADO SILMARAR, SOUSA ANDRÉGUSTAVOP, SANTOS PAULOC. General aspects of muscle glucose uptake. ACTA ACUST UNITED AC 2015; 87:351-68. [DOI: 10.1590/0001-3765201520140225] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/06/2014] [Indexed: 12/25/2022]
Abstract
Glucose uptake in peripheral tissues is dependent on the translocation of GLUT4 glucose transporters to the plasma membrane. Studies have shown the existence of two major signaling pathways that lead to the translocation of GLUT4. The first, and widely investigated, is the insulin activated signaling pathway through insulin receptor substrate-1 and phosphatidylinositol 3-kinase. The second is the insulin-independent signaling pathway, which is activated by contractions. Individuals with type 2 diabetes mellitus have reduced insulin-stimulated glucose uptake in skeletal muscle due to the phenomenon of insulin resistance. However, those individuals have normal glucose uptake during exercise. In this context, physical exercise is one of the most important interventions that stimulates glucose uptake by insulin-independent pathways, and the main molecules involved are adenosine monophosphate-activated protein kinase, nitric oxide, bradykinin, AKT, reactive oxygen species and calcium. In this review, our main aims were to highlight the different glucose uptake pathways and to report the effects of physical exercise, diet and drugs on their functioning. Lastly, with the better understanding of these pathways, it would be possible to assess, exactly and molecularly, the importance of physical exercise and diet on glucose homeostasis. Furthermore, it would be possible to assess the action of drugs that might optimize glucose uptake and consequently be an important step in controlling the blood glucose levels in diabetic patients, in addition to being important to clarify some pathways that justify the development of drugs capable of mimicking the contraction pathway.
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11
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Rider OJ, Ajufo E, Ali MK, Petersen SE, Nethononda R, Francis JM, Neubauer S. Myocardial tissue phase mapping reveals impaired myocardial tissue velocities in obesity. Int J Cardiovasc Imaging 2014; 31:339-47. [DOI: 10.1007/s10554-014-0548-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 10/04/2014] [Indexed: 11/29/2022]
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12
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Frankenberg NT, Lamb GD, Vissing K, Murphy RM. Subcellular fractionation reveals HSP72 does not associate with SERCA in human skeletal muscle following damaging eccentric and concentric exercise. J Appl Physiol (1985) 2014; 116:1503-11. [DOI: 10.1152/japplphysiol.00161.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Through its upregulation and/or translocation, heat shock protein 72 (HSP72) is involved in protection and repair of key proteins after physiological stress. In human skeletal muscle we investigated HSP72 protein after eccentric (ECC1) and concentric (CONC) exercise and repeated eccentric exercise (ECC2; 8 wk later) and whether it translocated from its normal cytosolic location to membranes/myofibrils. HSP72 protein increased ∼2-fold 24 h after ECC1, with no apparent change after CONC or ECC2. In resting (nonstressed) human skeletal muscle the total pool of HSP72 protein was present almost exclusively in the cytosolic fraction, and after each exercise protocol the distribution of HSP72 protein remained unaltered. Overall, the amount of HSP72 protein in the cytosol increased 24 h after ECC1, matching the fold increase that was measured in total HSP72 protein. To better ascertain the capabilities and limitations of HSP72, using quantitative Western blotting we determined the HSP72 protein content to be 11.4 μmol/kg wet weight in resting human vastus lateralis muscle, which is comprised of Type I (slow-twitch) and Type II (fast-twitch) fibers. HSP72 protein content was similar in individual Type I or II fiber segments. After physiological stress, HSP72 content can increase and, although the functional consequences of increased amounts of HSP72 protein are poorly understood, it has been shown to bind to and protect protein pumps like SERCA and Na+-K+-ATPase. Given no translocation of cytosolic HSP72, these findings suggest eccentric contractions, unlike other forms of stress such as heat, do not trigger tight binding of HSP72 to its primary membrane-bound target proteins, in particular SERCA.
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Affiliation(s)
- Noni T. Frankenberg
- Department of Zoology, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Graham D. Lamb
- Department of Zoology, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Kristian Vissing
- Section of Sport Science, Dept. of Public Health, Aarhus University, DK-8000 Aarhus, Denmark
| | - Robyn M. Murphy
- Department of Zoology, La Trobe University, Melbourne, Victoria, 3086, Australia
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13
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Ramírez Ríos S, Lamarche F, Cottet-Rousselle C, Klaus A, Tuerk R, Thali R, Auchli Y, Brunisholz R, Neumann D, Barret L, Tokarska-Schlattner M, Schlattner U. Regulation of brain-type creatine kinase by AMP-activated protein kinase: interaction, phosphorylation and ER localization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1271-83. [PMID: 24727412 DOI: 10.1016/j.bbabio.2014.03.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/25/2014] [Accepted: 03/31/2014] [Indexed: 12/25/2022]
Abstract
AMP-activated protein kinase (AMPK) and cytosolic brain-type creatine kinase (BCK) cooperate under energy stress to compensate for loss of adenosine triphosphate (ATP) by either stimulating ATP-generating and inhibiting ATP-consuming pathways, or by direct ATP regeneration from phosphocreatine, respectively. Here we report on AMPK-dependent phosphorylation of BCK from different species identified by in vitro screening for AMPK substrates in mouse brain. Mass spectrometry, protein sequencing, and site-directed mutagenesis identified Ser6 as a relevant residue with one site phosphorylated per BCK dimer. Yeast two-hybrid analysis revealed interaction of active AMPK specifically with non-phosphorylated BCK. Pharmacological activation of AMPK mimicking energy stress led to BCK phosphorylation in astrocytes and fibroblasts, as evidenced with a highly specific phospho-Ser6 antibody. BCK phosphorylation at Ser6 did not affect its enzymatic activity, but led to the appearance of the phosphorylated enzyme at the endoplasmic reticulum (ER), close to the ER calcium pump, a location known for muscle-type cytosolic creatine kinase (CK) to support Ca²⁺-pumping.
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Affiliation(s)
- Sacnicte Ramírez Ríos
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France
| | - Frédéric Lamarche
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France
| | - Cécile Cottet-Rousselle
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France
| | - Anna Klaus
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France
| | - Roland Tuerk
- Institute of Cell Biology, ETH Zurich, Switzerland
| | - Ramon Thali
- Institute of Cell Biology, ETH Zurich, Switzerland
| | - Yolanda Auchli
- Functional Genomics Center Zurich, ETH Zurich/University of Zurich, Switzerland
| | - René Brunisholz
- Functional Genomics Center Zurich, ETH Zurich/University of Zurich, Switzerland
| | | | - Luc Barret
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France
| | - Malgorzata Tokarska-Schlattner
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France
| | - Uwe Schlattner
- Univ. Grenoble Alpes, Laboratory of Fundamental and Applied Bioenergetics, Grenoble, France; Inserm, U1055, Grenoble, France.
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14
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Rider OJ, Lewis AJ, Neubauer S. Structural and Metabolic Effects of Obesity on the Myocardium and the Aorta. Obes Facts 2014; 7:329-338. [PMID: 25342107 PMCID: PMC5644846 DOI: 10.1159/000368429] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/08/2013] [Indexed: 12/12/2022] Open
Abstract
Obesity per se is a recognized risk factor for cardiovascular disease exerting independent adverse effects on the cardiovascular system. Despite this well documented link, the mechanisms by which obesity modulates cardiovascular risk are not well understood. Obesity is linked to a wide variety of cardiac changes, from subclinical diastolic dysfunction to end stage systolic heart failure. In addition, obesity causes changes in cardiac metabolism that make ATP production and utilization less efficient producing functional consequences that are linked to the increased rate of heart failure in this population. This review focuses on the cardiovascular structural and metabolic remodelling that occurs in obesity with and without co-morbidities and the potential links to increased mortality in this population. © 2014 S. Karger GmbH, Freiburg.
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Affiliation(s)
- Oliver J. Rider
- *Dr. Oliver J Rider, University of Oxford Centre for Clinical Magnetic Resonance Research, Level 0, John Radcliffe Hospital, Oxford OX3 9DU (UK),
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15
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Breckner A, Ganz M, Marcellin D, Richter J, Gerwin N, Rausch M. Effect of Calstabin1 depletion on calcium transients and energy utilization in muscle fibers and treatment opportunities with RyR1 stabilizers. PLoS One 2013; 8:e81277. [PMID: 24303040 PMCID: PMC3841141 DOI: 10.1371/journal.pone.0081277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 10/21/2013] [Indexed: 11/29/2022] Open
Abstract
Depletion of calstabin1 (FKBP12) from the RyR1 channel and consequential calcium leakage from the sarcoplasmic reticulum (SR) is found in certain disease conditions such as dystrophy, aging or muscle overuse. Here, we first assessed the effect of calstabin1 depletion on resting Ca2+ levels and transients. We found that depletion of calstabin1 with the calstabin1-dissociation compound FK506 increased the release of calcium from the SR by 14 % during tetanic stimulation (50 Hz, 300 ms) and delayed cytosolic calcium removal. However, we did not find a significant increase in resting cytosolic Ca2+ levels. Therefore, we tested if increased SERCA activity could counterbalance calcium leakage. By measuring the energy utilization of muscle fibers with and without FK506 treatment, we observed that FK506-treatment increased oxygen consumption by 125% compared to baseline levels. Finally, we found that pretreatment of muscle fibers with the RyR1 stabilizer JTV-519 led to an almost complete normalization of calcium flux dynamics and energy utilization. We conclude that cytosolic calcium levels are mostly preserved in conditions with leaky RyR1 channels due to increased SERCA activity. Therefore, we suggest that RyR1 leakiness might lead to chronic metabolic stress, followed by cellular damage, and RyR1 stabilizers could potentially protect diseased muscle tissue.
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Affiliation(s)
- Anke Breckner
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Magdalena Ganz
- Bioimaging Center, University of Konstanz, Konstanz, Germany
| | - David Marcellin
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Jens Richter
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Nicole Gerwin
- Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Martin Rausch
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
- * E-mail:
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16
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Abstract
Glucose is an important fuel for contracting muscle, and normal glucose metabolism is vital for health. Glucose enters the muscle cell via facilitated diffusion through the GLUT4 glucose transporter which translocates from intracellular storage depots to the plasma membrane and T-tubules upon muscle contraction. Here we discuss the current understanding of how exercise-induced muscle glucose uptake is regulated. We briefly discuss the role of glucose supply and metabolism and concentrate on GLUT4 translocation and the molecular signaling that sets this in motion during muscle contractions. Contraction-induced molecular signaling is complex and involves a variety of signaling molecules including AMPK, Ca(2+), and NOS in the proximal part of the signaling cascade as well as GTPases, Rab, and SNARE proteins and cytoskeletal components in the distal part. While acute regulation of muscle glucose uptake relies on GLUT4 translocation, glucose uptake also depends on muscle GLUT4 expression which is increased following exercise. AMPK and CaMKII are key signaling kinases that appear to regulate GLUT4 expression via the HDAC4/5-MEF2 axis and MEF2-GEF interactions resulting in nuclear export of HDAC4/5 in turn leading to histone hyperacetylation on the GLUT4 promoter and increased GLUT4 transcription. Exercise training is the most potent stimulus to increase skeletal muscle GLUT4 expression, an effect that may partly contribute to improved insulin action and glucose disposal and enhanced muscle glycogen storage following exercise training in health and disease.
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Affiliation(s)
- Erik A Richter
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
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17
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Fontes-Oliveira CC, Busquets S, Toledo M, Penna F, Paz Aylwin M, Sirisi S, Silva AP, Orpí M, García A, Sette A, Inês Genovese M, Olivan M, López-Soriano FJ, Argilés JM. Mitochondrial and sarcoplasmic reticulum abnormalities in cancer cachexia: altered energetic efficiency? Biochim Biophys Acta Gen Subj 2013. [PMID: 23200745 DOI: 10.1016/j.bbagen.2012.11.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cachexia is a wasting condition that manifests in several types of cancer, and the main characteristic is the profound loss of muscle mass. METHODS The Yoshida AH-130 tumor model has been used and the samples have been analyzed using transmission electronic microscopy, real-time PCR and Western blot techniques. RESULTS Using in vivo cancer cachectic model in rats, here we show that skeletal muscle loss is accompanied by fiber morphologic alterations such as mitochondrial disruption, dilatation of sarcoplasmic reticulum and apoptotic nuclei. Analyzing the expression of some factors related to proteolytic and thermogenic processes, we observed in tumor-bearing animals an increased expression of genes involved in proteolysis such as ubiquitin ligases Muscle Ring Finger 1 (MuRF-1) and Muscle Atrophy F-box protein (MAFBx). Moreover, an overexpression of both sarco/endoplasmic Ca(2+)-ATPase (SERCA1) and adenine nucleotide translocator (ANT1), both factors related to cellular energetic efficiency, was observed. Tumor burden also leads to a marked decreased in muscle ATP content. CONCLUSIONS In addition to muscle proteolysis, other ATP-related pathways may have a key role in muscle wasting, both directly by increasing energetic inefficiency, and indirectly, by affecting the sarcoplasmic reticulum-mitochondrial assembly that is essential for muscle function and homeostasis. GENERAL SIGNIFICANCE The present study reports profound morphological changes in cancer cachectic muscle, which are visualized mainly in alterations in sarcoplasmic reticulum and mitochondria. These alterations are linked to pathways that can account for energy inefficiency associated with cancer cachexia.
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Affiliation(s)
- Cibely Cristine Fontes-Oliveira
- Cancer Research Group, Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Diagonal 645 08028-Barcelona, Spain
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18
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Wiley SE, Andreyev AY, Divakaruni AS, Karisch R, Perkins G, Wall EA, van der Geer P, Chen YF, Tsai TF, Simon MI, Neel BG, Dixon JE, Murphy AN. Wolfram Syndrome protein, Miner1, regulates sulphydryl redox status, the unfolded protein response, and Ca2+ homeostasis. EMBO Mol Med 2013; 5:904-18. [PMID: 23703906 PMCID: PMC3779451 DOI: 10.1002/emmm.201201429] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 01/21/2023] Open
Abstract
Miner1 is a redox-active 2Fe2S cluster protein. Mutations in Miner1 result in Wolfram Syndrome, a metabolic disease associated with diabetes, blindness, deafness, and a shortened lifespan. Embryonic fibroblasts from Miner1(-/-) mice displayed ER stress and showed hallmarks of the unfolded protein response. In addition, loss of Miner1 caused a depletion of ER Ca(2+) stores, a dramatic increase in mitochondrial Ca(2+) load, increased reactive oxygen and nitrogen species, an increase in the GSSG/GSH and NAD(+)/NADH ratios, and an increase in the ADP/ATP ratio consistent with enhanced ATP utilization. Furthermore, mitochondria in fibroblasts lacking Miner1 displayed ultrastructural alterations, such as increased cristae density and punctate morphology, and an increase in O2 consumption. Treatment with the sulphydryl anti-oxidant N-acetylcysteine reversed the abnormalities in the Miner1 deficient cells, suggesting that sulphydryl reducing agents should be explored as a treatment for this rare genetic disease.
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Affiliation(s)
- Sandra E Wiley
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
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19
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Mahmmoud YA, Gaster M. Uncoupling of sarcoplasmic reticulum Ca²⁺-ATPase by N-arachidonoyl dopamine. Members of the endocannabinoid family as thermogenic drugs. Br J Pharmacol 2012; 166:2060-9. [PMID: 22335600 DOI: 10.1111/j.1476-5381.2012.01899.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND AND PURPOSE The sarcoplasmic reticulum Ca²⁺-ATPase (SERCA) plays a role in thermogenesis. The exogenous compound capsaicin increased SERCA-mediated ATP hydrolysis not coupled to Ca²⁺ transport. Here, we have sought to identify endogenous compounds that may function as SERCA uncoupling agents. EXPERIMENTAL APPROACH Using isolated SR vesicles from rabbits, we have screened for endogenous compounds that uncouple SERCA. We have also studied their ability to deplete cytoplasmic ATP from human skeletal muscle cells in culture. KEY RESULTS Studies on SR vesicles showed that the endogenous lipid metabolite N-arachidonoyl dopamine (NADA) was a potent stimulator of SERCA uncoupling. NADA stabilized an E₁-like pump conformation that had a lower dephosphorylation rate, low affinity for Ca²⁺ at the luminal sites and a specific proteinase K cleavage pattern involving protection of the C-terminal p83C fragment from further cleavage. Moreover, we found a significantly decreased cytoplasmic ATP levels following treatment of skeletal muscle cells with 100 nM NADA. This effect was dependent on the presence of glucose and abolished by pretreatment with the specific SERCA inhibitor thapsigargin, regardless of the presence of glucose. CONCLUSIONS AND IMPLICATIONS NADA is an endogenous molecule that may function as SERCA uncoupling agent in vivo. Members of the endocannabinoid family exert concerted actions on several Ca²⁺-handling proteins. Uncoupling of SERCA by exogenous compounds could be a novel post-mitochondrial strategy for reduction of cellular ATP levels. In addition, signalling networks leading to SERCA uncoupling can be explored to study the importance of this ion pump in pathophysiological conditions related to metabolism.
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Affiliation(s)
- Y A Mahmmoud
- Department of Biomedicine, University of Aarhus, Aarhus C, Denmark.
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20
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The mitochondrial Na+/Ca2+ exchanger upregulates glucose dependent Ca2+ signalling linked to insulin secretion. PLoS One 2012; 7:e46649. [PMID: 23056385 PMCID: PMC3466326 DOI: 10.1371/journal.pone.0046649] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 09/03/2012] [Indexed: 11/25/2022] Open
Abstract
Mitochondria mediate dual metabolic and Ca2+ shuttling activities. While the former is required for Ca2+ signalling linked to insulin secretion, the role of the latter in β cell function has not been well understood, primarily because the molecular identity of the mitochondrial Ca2+ transporters were elusive and the selectivity of their inhibitors was questionable. This study focuses on NCLX, the recently discovered mitochondrial Na+/Ca2+ exchanger that is linked to Ca2+ signalling in MIN6 and primary β cells. Suppression either of NCLX expression, using a siRNA construct (siNCLX) or of its activity, by a dominant negative construct (dnNCLX), enhanced mitochondrial Ca2+ influx and blocked efflux induced by glucose or by cell depolarization. In addition, NCLX regulated basal, but not glucose-dependent changes, in metabolic rate, mitochondrial membrane potential and mitochondrial resting Ca2+. Importantly, NCLX controlled the rate and amplitude of cytosolic Ca2+ changes induced by depolarization or high glucose, indicating that NCLX is a critical and rate limiting component in the cross talk between mitochondrial and plasma membrane Ca2+ signalling. Finally, knockdown of NCLX expression was followed by a delay in glucose-dependent insulin secretion. These findings suggest that the mitochondrial Na+/Ca2+ exchanger, NCLX, shapes glucose-dependent mitochondrial and cytosolic Ca2+ signals thereby regulating the temporal pattern of insulin secretion in β cells.
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21
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Pietka TA, Sulkin MS, Kuda O, Wang W, Zhou D, Yamada KA, Yang K, Su X, Gross RW, Nerbonne JM, Efimov IR, Abumrad NA. CD36 protein influences myocardial Ca2+ homeostasis and phospholipid metabolism: conduction anomalies in CD36-deficient mice during fasting. J Biol Chem 2012; 287:38901-12. [PMID: 23019328 DOI: 10.1074/jbc.m112.413609] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Sarcolemmal CD36 facilitates myocardial fatty acid (FA) uptake, which is markedly reduced in CD36-deficient rodents and humans. CD36 also mediates signal transduction events involving a number of cellular pathways. In taste cells and macrophages, CD36 signaling was recently shown to regulate store-responsive Ca(2+) flux and activation of Ca(2+)-dependent phospholipases A(2) that cycle polyunsaturated FA into phospholipids. It is unknown whether CD36 deficiency influences myocardial Ca(2+) handling and phospholipid metabolism, which could compromise the heart, typically during stresses. Myocardial function was examined in fed or fasted (18-22 h) CD36(-/-) and WT mice. Echocardiography and telemetry identified conduction anomalies that were associated with the incidence of sudden death in fasted CD36(-/-) mice. No anomalies or death occurred in WT mice during fasting. Optical imaging of perfused hearts from fasted CD36(-/-) mice documented prolongation of Ca(2+) transients. Consistent with this, knockdown of CD36 in cardiomyocytes delayed clearance of cytosolic Ca(2+). Hearts of CD36(-/-) mice (fed or fasted) had 3-fold higher SERCA2a and 40% lower phospholamban levels. Phospholamban phosphorylation by protein kinase A (PKA) was enhanced after fasting reflecting increased PKA activity and cAMP levels in CD36(-/-) hearts. Abnormal Ca(2+) homeostasis in the CD36(-/-) myocardium associated with increased lysophospholipid content and a higher proportion of 22:6 FA in phospholipids suggests altered phospholipase A(2) activity and changes in membrane dynamics. The data support the role of CD36 in coordinating Ca(2+) homeostasis and lipid metabolism and the importance of this role during myocardial adaptation to fasting. Potential relevance of the findings to CD36-deficient humans would need to be determined.
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Affiliation(s)
- Terri A Pietka
- Center for Human Nutrition, Washington University, St. Louis, Missouri 63110, USA
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22
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Larkins NT, Murphy RM, Lamb GD. Influences of temperature, oxidative stress, and phosphorylation on binding of heat shock proteins in skeletal muscle fibers. Am J Physiol Cell Physiol 2012; 303:C654-65. [DOI: 10.1152/ajpcell.00180.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heat shock proteins (HSPs) help maintain cellular function in stressful situations, but the processes controlling their interactions with target proteins are not well defined. This study examined the binding of HSP72, HSP25, and αB-crystallin in skeletal muscle fibers following various stresses. Rat soleus (SOL) and extensor digitorum longus (EDL) muscles were subjected in vitro to heat stress or strongly fatiguing stimulation. Superficial fibers were “skinned” by microdissection and HSP diffusibility assessed from the extent of washout following 10- to 30 min exposure to a physiological intracellular solution. In fibers from nonstressed (control) SOL muscle, >80% of each HSP is readily diffusible. However, after heating a muscle to 40°C for 30 min ∼95% of HSP25 and αB-crystallin becomes tightly bound at nonmembranous myofibrillar sites, whereas HSP72 bound at membranous sites only after heat treatment to ≥44°C. The ratio of reduced to oxidized cytoplasmic glutathione (GSH:GSSG) decreased approximately two- and fourfold after heating muscles to 40° and 45°C, respectively. The reducing agent dithiothreitol reversed HSP72 binding in heated muscles but had no effect on the other HSPs. Intense in vitro stimulation of SOL muscles, sufficient to elicit substantial oxidation-related loss of maximum force and approximately fourfold decrease in the GSH:GSSG ratio, had no effect on diffusibility of any of the HSPs. When skinned fibers from heat-treated muscles were bathed with additional exogenous HSP72, total binding increased approximately two- and 10-fold, respectively, in SOL and EDL fibers, possibly reflective of the relative sarco(endo)plasmic reticulum Ca2+-ATPase pump densities in the two fiber types. Phosphorylation at Ser59 on αB-crystallin and Ser85 on HSP25 increased with heat treatment but did not appear to determine HSP binding. The findings highlight major differences in the processes controlling binding of HSP72 and the two small HSPs. Binding was not directly related to cytoplasmic oxidative status, but oxidation of cysteine residues influenced HSP72 binding.
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Affiliation(s)
- Noni T. Larkins
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
| | - Robyn M. Murphy
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
| | - Graham D. Lamb
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
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23
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Baylor SM, Hollingworth S. Intracellular calcium movements during excitation-contraction coupling in mammalian slow-twitch and fast-twitch muscle fibers. ACTA ACUST UNITED AC 2012; 139:261-72. [PMID: 22450485 PMCID: PMC3315149 DOI: 10.1085/jgp.201210773] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In skeletal muscle fibers, action potentials elicit contractions by releasing calcium ions (Ca2+) from the sarcoplasmic reticulum. Experiments on individual mouse muscle fibers micro-injected with a rapidly responding fluorescent Ca2+ indicator dye reveal that the amount of Ca2+ released is three- to fourfold larger in fast-twitch fibers than in slow-twitch fibers, and the proportion of the released Ca2+ that binds to troponin to activate contraction is substantially smaller.
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Affiliation(s)
- Stephen M Baylor
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
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24
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Rider OJ, Francis JM, Ali MK, Holloway C, Pegg T, Robson MD, Tyler D, Byrne J, Clarke K, Neubauer S. Effects of catecholamine stress on diastolic function and myocardial energetics in obesity. Circulation 2012; 125:1511-9. [PMID: 22368152 DOI: 10.1161/circulationaha.111.069518] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Obesity is characterized by impaired cardiac energetics, which may play a role in the development of diastolic dysfunction and inappropriate shortness of breath. We assessed whether, in obesity, derangement of energetics and diastolic function is further altered during acute cardiac stress. METHODS AND RESULTS Normal-weight (body mass index, 22±2 kg/m(2); n=9-17) and obese (body mass index, 39±7 kg/m(2); n=17-46) subjects underwent assessment of diastolic left ventricular function (cine magnetic resonance imaging volume-time curve analysis) and cardiac energetics (phosphocreatine/ATP ratio; (31)P-magnetic resonance spectroscopy) at rest and during dobutamine stress (heart rate increase, 65±22% and 69±14%, respectively; P=0.61). At rest, obesity was associated with a 22% lower peak filling rate (P<0.001) and a 15% lower phosphocreatine/ATP ratio (1.73±0.40 versus 2.03±0.28; P=0.048). Peak filling rate correlated with fat mass, left ventricular mass, leptin, waist-to-hip ratio, and phosphocreatine/ATP ratio. On multivariable analysis, phosphocreatine/ATP was the only independent predictor of peak filling rate (β=0.50; P=0.03). During stress, a further reduction in phosphocreatine/ATP occurred in obese (from 1.73±0.40 to 1.53±0.50; P=0.03) but not in normal-weight (from 1.98±0.24 to 2.04±0.34; P=0.50) subject. For similar levels of inotropic stress, there were smaller increases in peak filling rate in obesity (38% versus 70%; P=0.01). CONCLUSIONS In obesity, cardiac energetics are further deranged during inotropic stress, in association with continued diastolic dysfunction. Myocardial energetics may play a key role in the impairment of diastolic function in obesity.
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Affiliation(s)
- Oliver J Rider
- Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford, UK.
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25
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Larkins NT, Murphy RM, Lamb GD. Absolute amounts and diffusibility of HSP72, HSP25, and αB-crystallin in fast- and slow-twitch skeletal muscle fibers of rat. Am J Physiol Cell Physiol 2011; 302:C228-39. [PMID: 21975426 DOI: 10.1152/ajpcell.00266.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heat shock proteins (HSPs) are essential for normal cellular stress responses. Absolute amounts of HSP72, HSP25, and αB-crystallin in rat extensor digitorum longus (EDL) and soleus (SOL) muscle were ascertained by quantitative Western blotting to better understand their respective capabilities and limitations. HSP72 content of EDL and SOL muscle was only ∼1.1 and 4.6 μmol/kg wet wt, respectively, and HSP25 content approximately twofold greater (∼3.4 and ∼8.9 μmol/kg, respectively). αB-crystallin content of EDL muscle was ∼4.9 μmol/kg but in SOL muscle was ∼30-fold higher (∼140 μmol/kg). To examine fiber heterogeneity, HSP content was also assessed in individual fiber segments; every EDL type II fiber had less of each HSP than any SOL type I fiber, whereas the two SOL type II fibers examined were indistinguishable from the EDL type II fibers. Sarcolemma removal (fiber skinning) demonstrated that 10-20% of HSP25 and αB-crystallin was sarcolemma-associated in SOL fibers. HSP diffusibility was assessed from the extent and rate of diffusion out of skinned fiber segments. In unstressed SOL fibers, 70-90% of each HSP was readily diffusible, whereas ∼95% remained tightly bound in fibers from SOL muscles heated to 45°C. Membrane disruption with Triton X-100 allowed dispersion of HSP72 and sarco(endo)plasmic reticulum Ca(2+)-ATPase pumps but did not alter binding of HSP25 or αB-crystallin. The amount of HSP72 in unstressed EDL muscle is much less than the number of its putative binding sites, whereas SOL type I fibers contain large amounts of αB-crystallin, suggesting its importance in normal cellular function without upregulation.
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Affiliation(s)
- Noni T Larkins
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
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Sjåland C, Lunde PK, Swift F, Munkvik M, Ericsson M, Lunde M, Boye S, Christensen G, Ellingsen Ø, Sejersted OM, Andersson KB. Slowed relaxation and preserved maximal force in soleus muscles of mice with targeted disruption of the Serca2 gene in skeletal muscle. J Physiol 2011; 589:6139-55. [PMID: 21946846 DOI: 10.1113/jphysiol.2011.211987] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Sarcoplasmic reticulum Ca(2+) ATPases (SERCAs) play a major role in muscle contractility by pumping Ca(2+) from the cytosol into the sarcoplasmic reticulum (SR) Ca(2+) store, allowing muscle relaxation and refilling of the SR with releasable Ca(2+). Decreased SERCA function has been shown to result in impaired muscle function and disease in human and animal models. In this study, we present a new mouse model with targeted disruption of the Serca2 gene in skeletal muscle (skKO) to investigate the functional consequences of reduced SERCA2 expression in skeletal muscle. SkKO mice were viable and basic muscle structure was intact. SERCA2 abundance was reduced in multiple muscles, and by as much as 95% in soleus muscle, having the highest content of slow-twitch fibres (40%). The Ca(2+) uptake rate was significantly reduced in SR vesicles in total homogenates. We did not find any compensatory increase in SERCA1 or SERCA3 abundance, or altered expression of several other Ca(2+)-handling proteins. Ultrastructural analysis revealed generally well-preserved muscle morphology, but a reduced volume of the longitudinal SR. In contracting soleus muscle in vitro preparations, skKO muscles were able to fully relax, but with a significantly slowed relaxation time compared to controls. Surprisingly, the maximal force and contraction rate were preserved, suggesting that skKO slow-twitch fibres may be able to contribute to the total muscle force despite loss of SERCA2 protein. Thus it is possible that SERCA-independent mechanisms can contribute to muscle contractile function.
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Affiliation(s)
- Cecilie Sjåland
- Institute for Experimental Medical Research, Oslo University Hospital, Ullevål, and University of Oslo, Oslo, Norway
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