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Dedert CJ, Bagdady KR, Fisher JS. Prior Treatment with AICAR Causes the Selective Phosphorylation of mTOR Substrates in C2C12 Cells. Curr Issues Mol Biol 2023; 45:8040-8052. [PMID: 37886951 PMCID: PMC10605383 DOI: 10.3390/cimb45100508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/05/2023] [Accepted: 09/27/2023] [Indexed: 10/28/2023] Open
Abstract
Metabolic stress in skeletal muscle cells causes sustained metabolic changes, but the mechanisms of the prolonged effects are not fully known. In this study, we tested C2C12 cells with the AMP-activated protein kinase (AMPK) stimulator AICAR and measured the changes in the metabolic pathways and signaling kinases. AICAR caused an acute increase in the phosphorylation of the AMPK target ULK1, the mTORC1 substrate S6K, and the mTORC2 target Akt. Intriguingly, prior exposure to AICAR only decreased glucose-6 phosphate dehydrogenase activity when it underwent three-hour recovery after exposure to AICAR in a bicarbonate buffer containing glucose (KHB) instead of Dulbecco's Minimum Essential Medium (DMEM). The phosphorylation of the mTORC1 target S6K was increased after recovery in DMEM but not KHB, although this appeared to be specific to S6K, as the phosphorylation of the mTORC1 target site on ULK1 was not altered when the cells recovered in DMEM. The phosphorylation of mTORC2 target sites was also heterogenous under these conditions, with Akt increasing at serine 473 while other targets (SGK1 and PKCα) were unaffected. The exposure of cells to rapamycin (an mTORC1 inhibitor) and PP242 (an inhibitor of both mTOR complexes) revealed the differential phosphorylation of mTORC2 substrates. Taken together, the data suggest that prior exposure to AICAR causes the selective phosphorylation of mTOR substrates, even after prolonged recovery in a nutrient-replete medium.
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2
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Schneider T, Tan Y, Li H, Fisher JS, Zhang D. Photoglobin, a distinct family of non-heme binding globins, defines a potential photosensor in prokaryotic signal transduction systems. Comput Struct Biotechnol J 2022; 20:261-273. [PMID: 35024098 PMCID: PMC8717448 DOI: 10.1016/j.csbj.2021.12.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 11/17/2022] Open
Abstract
Globins constitute an ancient superfamily of proteins, exhibiting enormous structural and functional diversity, as demonstrated by many heme-binding families and two non-heme binding families that were discovered in bacterial stressosome component RsbR and in light-harvesting phycobiliproteins (phycocyanin) in cyanobacteria and red algae. By comprehensively exploring the globin repertoire using sensitive computational analyses of sequences, structures, and genomes, we present the identification of the third family of non-heme binding globins—the photoglobin. By conducting profile-based comparisons, clustering analyses, and structural modeling, we demonstrate that photoglobin is related to, but distinct from, the phycocyanin family. Photoglobin preserves a potential ligand-binding pocket, whose residue configuration closely resembles that of phycocyanin, indicating that photoglobin potentially binds to a comparable linear tetrapyrrole. By exploring the contextual information provided by the photoglobin’s domain architectures and gene-neighborhoods, we found that photoglobin is frequently associated with the B12-binding light sensor domain and many domains typical of prokaryotic signal transduction systems. Structural modeling using AlphaFold2 demonstrated that photoglobin and B12-binding domains form a structurally conserved hub among different domain architecture contexts. Based on these strong associations, we predict that the coupled photoglobin and B12-binding domains act as a light-sensing regulatory bundle, with each domain sensing different wavelengths of light resulting in switch-like regulation of downstream signaling effectors. Thus, based on the above lines of evidence, we present a distinct non-heme binding globin family and propose that it may define a new type of light sensor, by means of a linear tetrapyrrole, in complex prokaryotic signal transduction systems.
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Affiliation(s)
- Theresa Schneider
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63105, United States
| | - Yongjun Tan
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63105, United States
| | - Huan Li
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63105, United States
| | - Jonathan S Fisher
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63105, United States
| | - Dapeng Zhang
- Department of Biology, College of Arts & Sciences, Saint Louis University, Saint Louis, MO 63105, United States.,Program of Bioinformatics and Computational Biology, College of Arts & Sciences, Saint Louis University, MO 63103, United States
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3
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Decoteau MA, Steuterman S, Kurian SM, Case J, Lewis PR, Fisher JS, Schaffer RL, Marsh CL. Mitigation of radiation exposure during surgical hepatectomy after yttrium-90 radioembolization. J Radiol Prot 2021; 41:N1-N11. [PMID: 34107455 DOI: 10.1088/1361-6498/ac09c0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/09/2021] [Indexed: 06/12/2023]
Abstract
Yttrium-90 (Y-90) radioembolization for the treatment of hepatocellular carcinoma can present safety challenges when transplanting recently treated Y-90 patients. To reduce surgeons' contact with radioactive tissue and remain within occupational dose limits, current guidelines recommend delaying transplants at least 14 days, if possible. We wanted to determine the level of radiation exposure to the transplant surgeon when explanting an irradiated liver before the recommended decay period. Anex-vivoradiation exposure analysis was conducted on the explanted liver of a patient who received Y-90 therapy 46 h prior to orthotopic liver transplant. To estimate exposure to the surgeon's hands, radiation dosimeter rings were placed inside three different surgical glove configurations and exposed to the explanted liver. Estimated radiation doses corrected for Y-90 decay were calculated. Radiation safety gloves performed best, with an average radiation exposure rate of 5.36 mSV h-1in the static hand position, an 83% reduction in exposure over controls with no glove (31.31 mSv h-1). Interestingly, non-radiation safety gloves also demonstrated reduced exposure rates, well below occupational regulation limits. Handling of Y-90 radiated organs within the immediate post-treatment period can be done safely and does not exceed federal occupational dose limits if appropriate gloves and necessary precautions are exercised.
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Affiliation(s)
- Mary A Decoteau
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
- Department of General Surgery, Naval Medical Center San Diego, San Diego, CA, United States of America
| | - Steven Steuterman
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
- Department of Medical Physics and Radiation Safety, Scripps Clinic and Scripps Green Hospital, La Jolla, CA, United States of America
| | - Sunil M Kurian
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
- Scripps Clinic Bio-Repository and Bio-Informatics Core, Scripps Green Hospital, La Jolla, CA, United States of America
| | - Jamie Case
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
- Scripps Clinic Bio-Repository and Bio-Informatics Core, Scripps Green Hospital, La Jolla, CA, United States of America
| | - Paul R Lewis
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
- Department of General Surgery, Naval Medical Center San Diego, San Diego, CA, United States of America
| | - Jonathan S Fisher
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
| | - Randolph L Schaffer
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
| | - Christopher L Marsh
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic and Scripps Green Hospital, 10666 N Torrey Pines Road, 200N, La Jolla, CA 92037, United States of America
- Scripps Clinic Bio-Repository and Bio-Informatics Core, Scripps Green Hospital, La Jolla, CA, United States of America
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4
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Fisher JS. Intramyofibrillar glycogen drives endurance exercise capacity. J Physiol 2020; 598:4145-4146. [PMID: 32770546 DOI: 10.1113/jp280546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jonathan S Fisher
- Department of Biology and Center for Cardiovascular Research, Saint Louis University, 3507 Laclede Ave, St Louis, MO, 63103, USA
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5
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Eccardt AM, Pelzel RJ, Mattathil L, Moon YA, Mannino MH, Janowiak BE, Fisher JS. A peroxidase mimetic protects skeletal muscle cells from peroxide challenge and stimulates insulin signaling. Am J Physiol Cell Physiol 2020; 318:C1214-C1225. [PMID: 32348172 DOI: 10.1152/ajpcell.00167.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Reactive oxygen species such as hydrogen peroxide have been implicated in causing metabolic dysfunction such as insulin resistance. Heme groups, either by themselves or when incorporated into proteins, have been shown to scavenge peroxide and demonstrate protective effects in various cell types. Thus, we hypothesized that a metalloporphyrin similar in structure to heme, Fe(III)tetrakis(4-benzoic acid)porphyrin (FeTBAP), would be a peroxidase mimetic that could defend cells against oxidative stress. After demonstrating that FeTBAP has peroxidase activity with reduced nicotinamide adenine dinucleotide phosphate (NADPH) and NADH as reducing substrates, we determined that FeTBAP partially rescued C2C12 myotubes from peroxide-induced insulin resistance as measured by phosphorylation of AKT (S473) and insulin receptor substrate 1 (IRS-1, Y612). Furthermore, we found that FeTBAP stimulates insulin signaling in myotubes and mouse soleus skeletal muscle to about the same level as insulin for phosphorylation of AKT, IRS-1, and glycogen synthase kinase 3β (S9). We found that FeTBAP lowers intracellular peroxide levels and protects against carbonyl formation in myotubes exposed to peroxide. Additionally, we found that FeTBAP stimulates glucose transport in myotubes and skeletal muscle to about the same level as insulin. We conclude that a peroxidase mimetic can blunt peroxide-induced insulin resistance and also stimulate insulin signaling and glucose transport, suggesting a possible role of peroxidase activity in regulation of insulin signaling.
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Affiliation(s)
- Amanda M Eccardt
- Department of Biology, Saint Louis University, St. Louis, Missouri
| | - Ross J Pelzel
- Department of Biology, Saint Louis University, St. Louis, Missouri
| | - Lyn Mattathil
- Department of Biology, Saint Louis University, St. Louis, Missouri
| | - Yerin A Moon
- Department of Biology, Saint Louis University, St. Louis, Missouri
| | - Mark H Mannino
- Department of Biology, Saint Louis University, St. Louis, Missouri
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Patel A, Vendrell-Gonzalez S, Haas G, Marcinczyk M, Ziemkiewicz N, Talovic M, Fisher JS, Garg K. Regulation of Myogenic Activity by Substrate and Electrical Stimulation In Vitro. Biores Open Access 2019; 8:129-138. [PMID: 31367477 PMCID: PMC6664826 DOI: 10.1089/biores.2019.0016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Skeletal muscle has a remarkable regenerative capacity in response to mild injury. However, when muscle is severely injured, muscle regeneration is impaired due to the loss of muscle-resident stem cells, known as satellite cells. Fibrotic tissue, primarily comprising collagen I (COL), is deposited with this critical loss of muscle. In recent studies, supplementation of laminin (LM)-111 has been shown to improve skeletal muscle regeneration in several models of disease and injury. Additionally, electrical stimulation (E-stim) has been investigated as a possible rehabilitation therapy to improve muscle's functional recovery. This study investigated the role of E-stim and substrate in regulating myogenic response. C2C12 myoblasts were allowed to differentiate into myotubes on COL- and LM-coated polydimethylsiloxane molds. The myotubes were subjected to E-stim and compared with nonstimulated controls. While E-stim resulted in increased myogenic activity, irrespective of substrate, LM supported increased proliferation and uniform distribution of C2C12 myoblasts. In addition, C2C12 myoblasts cultured on LM showed higher Sirtuin 1, mammalian target of rapamycin, desmin, nitric oxide, and vascular endothelial growth factor expression. Taken together, these results suggest that an LM substrate is more conducive to myoblast growth and differentiation in response to E-stim in vitro.
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Affiliation(s)
- Anjali Patel
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
| | - Sara Vendrell-Gonzalez
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
| | - Gabriel Haas
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
| | - Madison Marcinczyk
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
| | - Natalia Ziemkiewicz
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
| | - Muhamed Talovic
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
| | - Jonathan S Fisher
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, Missouri
| | - Koyal Garg
- Department of Biomedical Engineering, Parks College of Engineering, Aviation, and Technology, Saint Louis University, St. Louis, Missouri
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7
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Mannino MH, Patel RS, Eccardt AM, Perez Magnelli RA, Robinson CLC, Janowiak BE, Warren DE, Fisher JS. Myoglobin as a versatile peroxidase: Implications for a more important role for vertebrate striated muscle in antioxidant defense. Comp Biochem Physiol B Biochem Mol Biol 2019; 234:9-17. [PMID: 31051268 DOI: 10.1016/j.cbpb.2019.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/29/2019] [Accepted: 04/23/2019] [Indexed: 12/17/2022]
Abstract
Myoglobins (Mb) are ubiquitous proteins found in striated muscle of nearly all vertebrate taxa. Although their function is most commonly associated with facilitating oxygen storage and diffusion, Mb has also been implicated in cellular antioxidant defense. The oxidized (Fe3+) form of Mb (metMB) can react with hydrogen peroxide (H2O2) to produce ferrylMb. FerrylMb can be reduced back to metMb for another round of reaction with H2O2. In the present study, we have shown that horse skeletal muscle Mb displays peroxidase activity using 2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB) as reducing substrates, as well as the biologically-relevant substrates NADH/NADPH, ascorbate, caffeic acid, and resveratrol. We have also shown that ferrylMb can be reduced by both ethanol and acetaldehyde, which are known to accumulate in some vertebrate tissues under anaerobic conditions, such as anoxic goldfish and crucian carp, implying a potential mechanism for ethanol detoxification in striated muscle. We found that metMb peroxidase activity is pH-dependent, increasing as pH decreases from 7.4 to 6.1, which is biologically relevant to anaerobic vertebrate muscle when incurring intracellular lactic acidosis. Finally, we found that metMb reacts with hypochlorite in a heme-dependent fashion, indicating that Mb could play a role in hypochlorite detoxification. Taken together, these data suggest that Mb peroxidase activity might be an important antioxidant mechanism in vertebrate cardiac and skeletal muscle under a variety of physiological conditions, such as those that might occur in contracting skeletal muscle or during hypoxia.
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8
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Niederhaus SV, Carrico RJ, Prentice MA, Fox AC, Mujtaba MA, Dunn TB, Olaitan OK, Fisher JS, Stratta RJ, Farney AC, Odorico JS, Fridell JA. C-peptide levels do not correlate with pancreas allograft failure: Multicenter retrospective analysis and discussion of the new OPT definition of pancreas allograft failure. Am J Transplant 2019; 19:1178-1186. [PMID: 30230218 DOI: 10.1111/ajt.15118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 08/24/2018] [Accepted: 09/08/2018] [Indexed: 01/25/2023]
Abstract
The OPTN Pancreas Transplantation Committee performed a multicenter retrospective study to determine if undetectable serum C-peptide levels correspond to center-reported pancreas graft failures. C-peptide data from seven participating centers (n = 415 graft failures for transplants performed from 2002 to 2012) were analyzed pretransplant, at graft failure, and at return to insulin. One hundred forty-nine C-peptide values were submitted at pretransplant, 94 at return to insulin, and 233 at graft failure. There were 77 transplants with two available values (at pretransplant and at graft failure). For recipients in the study with pretransplant C-peptide <0.75 ng/mL who had a posttransplant C-peptide value available (n = 61), graft failure was declared at varying levels of C-peptide. High C-peptide values at graft failure were not explained by nonfasting testing or by individual center bias. Transplant centers declare pancreas graft failure at varying levels of C-peptide and do not consistently report C-peptide data. Until February 28, 2018, OPTN did not require reporting of posttransplant C-peptide levels and it appears that C-peptide levels are not consistently used for evaluating graft function. C-peptide levels should not be used as the sole criterion for the definition of pancreas graft failure.
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Affiliation(s)
- Silke V Niederhaus
- Department of Surgery, University of Maryland Medical Center, Baltimore, Maryland
| | | | | | - Abigail C Fox
- United Network for Organ Sharing, Richmond, Virginia
| | - Muhammad A Mujtaba
- Division of Nephrology and Transplant, Department of Medicine, University of Texas Medical Branch, Galveston, Texas
| | - Ty B Dunn
- Division of Transplantation, Department of Surgery, University of Minnesota, Minneapolis, Minnsota
| | - Oyedolamu K Olaitan
- Section of Abdominal Transplantation, Department of General Surgery, Rush Medical College, Chicago, Illinois
| | - Jonathan S Fisher
- Scripps Center for Organ Transplantation, Scripps Health, La Jolla, California
| | - Robert J Stratta
- Department of Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Alan C Farney
- Department of Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Jon S Odorico
- Department of Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Jonathan A Fridell
- Department of Surgery, Indiana University School of Medicine, Indianapolis, Indiana
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9
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Eccardt AM, Pelzel RJ, Mattathil L, Moon YA, Mannino MH, Janowiak BE, Fisher JS. A Metalloporphyrin that Serves as a Peroxidase and Stimulates Insulin Signaling in Skeletal Muscle. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.543.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Lyn Mattathil
- Department of BiologySaint Louis UniversitySt. LouisMO
| | - Yerin A. Moon
- Department of BiologySaint Louis UniversitySt. LouisMO
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10
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Kelly SC, Patel NN, Eccardt AM, Fisher JS. Glucose-dependent trans-plasma membrane electron transport and p70 S6k phosphorylation in skeletal muscle cells. Redox Biol 2018; 27:101075. [PMID: 30578122 PMCID: PMC6859557 DOI: 10.1016/j.redox.2018.101075] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 11/05/2022] Open
Abstract
The reduction of extracellular oxidants by intracellular electrons is known as trans-plasma membrane electron transport (tPMET). The goal of this study was to characterize a role of tPMET in the sensing of glucose as a physiological signal. tPMET from C2C12 myotubes was monitored using a cell-impermeable extracellular electron acceptor, water-soluble tetrazolium salt-1 (WST-1). Superoxide dismutase in the incubation medium or exposure to an NADPH oxidase (NOX) isoform 1/4 inhibitor suppressed WST-1 reduction by 70%, suggesting a role of NOXs in tPMET. There was a positive correlation between medium glucose concentration and WST-1 reduction, suggesting that tPMET is a glucose-sensing process. WST-1 reduction was also decreased by an inhibitor of the pentose phosphate pathway, dehydroepiandrosterone. In contrast, glycolytic inhibitors, 3PO and sodium fluoride, did not affect WST-1 reduction. Thus, it appears that glucose uptake and processing in the pentose phosphate pathway drives NOX-dependent tPMET. Western blot analysis demonstrated that p70S6k phosphorylation is glucose-dependent, while the phosphorylation of AKT and MAPK did not differ in the presence or absence of glucose. Further, phosphorylation of p70S6k was dependent upon NOX enzymes. Finally, glucose was required for full stimulation of p70S6k by insulin, again in a fashion prevented by NOX inhibition. Taken together, the data suggest that muscle cells have a novel glucose-sensing mechanism dependent on NADPH production and NOX activity, culminating in increased p70S6k phosphorylation.
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Affiliation(s)
- Shannon C Kelly
- Department of Biology, Saint Louis University, St. Louis, MO, United States
| | - Neej N Patel
- Department of Biology, Saint Louis University, St. Louis, MO, United States
| | - Amanda M Eccardt
- Department of Biology, Saint Louis University, St. Louis, MO, United States
| | - Jonathan S Fisher
- Department of Biology, Saint Louis University, St. Louis, MO, United States.
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11
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Schutt RJ, Gower JR, Fisher JS. Defining Optimal Immunosuppression after Kidney after Heart Transplant. J Am Coll Surg 2018. [DOI: 10.1016/j.jamcollsurg.2018.08.597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Abstract
Trans-plasma membrane electron transport (tPMET) plays a role in protection of cells from intracellular reductive stress as well as protection from damage by extracellular oxidants. This process of transporting electrons from intracellular reductants to extracellular oxidants is not well defined. Here we present spectrophotometric assays by C2C12 myotubes to monitor tPMET utilizing the extracellular electron acceptors: water-soluble tetrazolium salt-1 (WST-1) and 2,6-dichlorophenolindophenol (DPIP or DCIP). Through reduction of these electron acceptors, we are able to monitor this process in a real-time analysis. With the addition of enzymes such as ascorbate oxidase (AO) and superoxide dismutase (SOD) to the assays, we can determine which portion of tPMET is due to ascorbate export or superoxide production, respectively. While WST-1 was shown to produce stable results with low background, DPIP was able to be re-oxidized after the addition of AO and SOD, which was demonstrated with spectrophotometric analysis. This method demonstrates a real-time, multi-well, quick spectrophotometric assay with advantages over other methods used to monitor tPMET, such as ferricyanide (FeCN) and ferricytochrome c reduction.
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13
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Kelly SC, Patel NN, Fisher JS. Glucose and NADPH Oxidase Dependent Trans‐plasma Membrane Electron Transport. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.771.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Schutt RJ, Case J, Barrick B, Toll AE, Schaffer RL, Fisher JS, Rice JC, Marsh CL. Living Kidney Transplant: The Influence of Intra-Operative Hemodynamics on Delayed Graft Function. ACTA ACUST UNITED AC 2017. [DOI: 10.14302/issn.2576-9359.jot-17-1807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ryan J. Schutt
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
| | - Jamie Case
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
| | - Bethany Barrick
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
| | - Alice E. Toll
- Research Department, United Network for Organ Sharing, 700 North 4th Street, Richmond, Virginia
| | - Randolph L. Schaffer
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
| | - Jonathan S. Fisher
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
| | - James C. Rice
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
| | - Christopher L. Marsh
- Scripps Center for Organ and Cell Transplantation, Scripps Green Hospital, 10666 North Torrey Road, La Jolla, California
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15
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Henderson ML, Clayville KA, Fisher JS, Kuntz KK, Mysel H, Purnell TS, Schaffer RL, Sherman LA, Willock EP, Gordon EJ. Social media and organ donation: Ethically navigating the next frontier. Am J Transplant 2017; 17:2803-2809. [PMID: 28744966 DOI: 10.1111/ajt.14444] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/30/2017] [Accepted: 07/17/2017] [Indexed: 01/25/2023]
Abstract
As the organ shortage continues to grow, the creation of social media communities by transplant hospitals and the public is rapidly expanding to increase the number of living donors. Social media communities are arranged in myriad ways and without standardization, raising concerns about transplant candidates' and potential donors' autonomy and quality of care. Social media communities magnify and modify extant ethical issues in deceased and living donation related to privacy, confidentiality, professionalism, and informed consent, and increase the potential for undue influence and coercion for potential donors and transplant candidates. Currently, no national ethical guidelines have been developed in the United States regarding the use of social media to foster organ transplantation. We provide an ethical framework to guide transplant stakeholders in using social media for public and patient communication about transplantation and living donation, and offer recommendations for transplant clinical practice and future research.
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Affiliation(s)
- M L Henderson
- Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - J S Fisher
- Scripps Clinic/Green Hospital, La Jolla, CA, USA
| | - K K Kuntz
- The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - H Mysel
- The Living Kidney Donors Network, Chicago, IL, USA
| | - T S Purnell
- Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - R L Schaffer
- Scripps Clinic/Green Hospital, La Jolla, CA, USA
| | - L A Sherman
- Medical College of Wisconsin Milwaukee, WI, USA
| | - E P Willock
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - E J Gordon
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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Brill JB, Schutt RJ, Wallace JD, Case J, Moore N, Marsh CL, Schaffer RL, Fisher JS. Cannabis and Other Substance Use in Solid Organ Transplant Patients. J Am Coll Surg 2017. [DOI: 10.1016/j.jamcollsurg.2017.07.981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Schutt RJ, Case J, Barrick B, Harper AM, Quigley M, Fisher JS, Schaffer RL, Marsh CL. Donor-Specific Antibodies in the Steroid-Free Renal Transplant Population. J Am Coll Surg 2017. [DOI: 10.1016/j.jamcollsurg.2017.07.983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
IMPORTANCE Patients in the United States waiting for kidney transplantation die in increasing numbers owing to the severe kidney shortage, which might be alleviated by compensating living kidney donors. OBJECTIVE To determine the willingness of voting US citizens to become living kidney donors and to ascertain the potential influence of compensation for donation. DESIGN, SETTING, AND PARTICIPANTS A professionally designed quantitative survey was administered by an international polling firm in June 2014. Information was collected on willingness to donate a kidney and the potential influence of compensation ($50 000); survey data included respondent age, income, education level, sex, US region, race/ethnicity, marital status, political affiliation, likelihood to vote, and employment status. The survey was performed via a random-digit dialing process that selected respondents via both landlines and mobile telephones to improve population representation. The survey included 1011 registered US voters likely to vote. MAIN OUTCOMES AND MEASURES The degree to which the US voting public is willing to donate a kidney and the perceptions of current voters toward paying living kidney donors. RESULTS Of the 1011 respondents, 427 were male and 584 were female, with 43% of participants between ages 45 and 64 years. With respondents grouped by willingness to donate, we found that 689 (68%) would donate a kidney to anyone and 235 (23%) only to certain persons; 87 (9%) would not donate. Most (59%) indicated that payment of $50 000 would make them even more likely to donate a kidney, 32% were unmoved by compensation, and 9% were negatively influenced by payment. CONCLUSIONS AND RELEVANCE Most US voters view living kidney donation positively, and most would be motivated toward donor nephrectomy if offered a payment of $50 000. Because most registered voters favor such payments, and because thousands of lives might be saved should compensation increase the number of transplantable kidneys, laws and regulations prohibiting donor compensation should be modified to allow pilot studies of financial incentives for living kidney donors. Outcomes of such trials could then result in evidence-based policies, which would incorporate fair and just compensation to those persons willing to undergo donor nephrectomy.
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Affiliation(s)
- Thomas G Peters
- University of Florida College of Medicine, Jacksonville2FAIR Foundation, Palm Desert, California
| | | | - Robert G Gish
- FAIR Foundation, Palm Desert, California4Liver Transplant Program, Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University Medical Center, Stanford, California
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Mittelman M, Thiessen C, Chon WJ, Clayville K, Cronin DC, Fisher JS, Fry-Revere S, Gross JA, Hanneman J, Henderson ML, Ladin K, Mysel H, Sherman LA, Willock L, Gordon EJ. Miscommunicating NOTA Can Be Costly to Living Donors. Am J Transplant 2017; 17:578-580. [PMID: 27599256 DOI: 10.1111/ajt.14036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M Mittelman
- American Living Organ Donor Network, Philadelphia, PA
| | - C Thiessen
- Yale University School of Medicine, New Haven, CT
| | - W J Chon
- University of Arkansas for Medical Sciences, Little Rock, AR
| | - K Clayville
- Northwestern University Feinberg School of Medicine, Chicago, IL
| | - D C Cronin
- Medical College of Wisconsin, Milwaukee, WI
| | - J S Fisher
- Scripps Clinic/Green Hospital, La Jolla, CA
| | - S Fry-Revere
- American Living Organ Donor Network, Center for Ethical Solutions, Washington, DC
| | | | - J Hanneman
- Northwestern University Feinberg School of Medicine, Chicago, IL
| | | | - K Ladin
- Tufts University, Boston, MA
| | - H Mysel
- Living Kidney Donor Network, Winnetka, IL
| | - L A Sherman
- Northwestern University Feinberg School of Medicine, Chicago, IL
| | - L Willock
- Biomedical Institutional Review Board, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - E J Gordon
- Northwestern University Feinberg School of Medicine, Chicago, IL
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Spears LD, Renth AL, McKuin MR, Kennedy AR, Andrisse S, Briggs NE, Fisher JS. A role for ataxia telangiectasia mutated in insulin-independent stimulation of glucose transport. Trends Cell Mol Biol 2017; 12:49-56. [PMID: 30542240 PMCID: PMC6287632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Literature reports suggest that ataxia telangiectasia mutated (ATM) can activate the AMP-activated protein kinase (AMPK), a protein that can stimulate glucose transport in skeletal muscle. We hypothesized that 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, would increase glucose transport in mouse extensor digitorum longus (EDL) muscles in an ATM-dependent manner. AICAR-stimulated glucose transport was prevented by the ATM inhibitor KU-55933 despite normal stimulation of AMPK phosphorylation. Consistent with this, AICAR caused AMPK phosphorylation but not an increase of glucose transport in ATM-deficient (ATM-/-) muscles. S231 of TBC1D1 matches the sequence motif of ATM substrates, and phosphorylation of this site is known to inhibit TBC1D1 and lead to increased glucose transport. Accordingly, we assessed TBC1D1 phosphorylation and found that AICAR-stimulated phosphorylation of TBC1D1 at S231 did not occur in ATM-/- muscles. However, activation of ATM without activation of AMPK was insufficient to increase TBC1D1 phosphorylation. The data suggest that ATM plays a role in AICAR-stimulated glucose transport downstream of AMPK.
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Affiliation(s)
| | - Allyson L. Renth
- Department of Biology, Saint Louis University, St. Louis, Missouri, USA
| | - Michael R. McKuin
- Department of Biology, Saint Louis University, St. Louis, Missouri, USA
| | - Anne R. Kennedy
- Department of Biology, Saint Louis University, St. Louis, Missouri, USA
| | | | - Nell E. Briggs
- Department of Biology, Saint Louis University, St. Louis, Missouri, USA
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Fisher JS, Butt Z, Friedewald J, Fry-Revere S, Hanneman J, Henderson ML, Ladin K, Mysel H, Preczewski L, Sherman LA, Thiessen C, Gordon EJ. Between Scylla and Charybdis: charting an ethical course for research into financial incentives for living kidney donation. Am J Transplant 2015; 15:1180-6. [PMID: 25833728 DOI: 10.1111/ajt.13234] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 12/15/2014] [Accepted: 12/25/2015] [Indexed: 01/25/2023]
Abstract
New approaches to address the kidney scarcity in the United States are urgently needed. The greatest potential source of kidneys is from living donors. Proposals to offer financial incentives to increase living kidney donation rates remain highly controversial. Despite repeated calls for a pilot study to assess the impact of financial compensation on living kidney donation rates, many fear that financial incentives will exploit vulnerable individuals and cast the field of transplantation in a negative public light, ultimately reducing donation rates. This paper provides an ethical justification for conducting a pilot study of a federally regulated approach to providing financial incentives to living kidney donors, with the goal of assessing donors' perceptions.
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Affiliation(s)
- J S Fisher
- Scripps Center for Organ and Cell Transplantation, Scripps Clinic/Green Hospital, La Jolla, CA
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Weiss EP, Royer NK, Fisher JS, Holloszy JO, Fontana L. Postprandial plasma incretin hormones in exercise-trained versus untrained subjects. Med Sci Sports Exerc 2014; 46:1098-103. [PMID: 24576859 DOI: 10.1249/mss.0000000000000204] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
INTRODUCTION After food ingestion, the incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are secreted by the intestines into circulation where they act on the pancreas to promote insulin secretion. We evaluated the hypothesis that low postprandial plasma insulin levels in lean exercise-trained individuals are associated with low concentrations of incretin hormones. METHODS A cross-sectional study was performed to compare postprandial incretin hormone levels in lean endurance exercise-trained individuals (EX; n = 14, ≥40 yr) and age- and sex-matched, nonobese, sedentary control subjects (CON, n = 14). The main outcome measures were GLP-1, GIP, insulin, and glucose incremental areas under the curve (AUC) as measured in plasma samples collected during a 2-h,75-g oral glucose tolerance test (OGTT). RESULTS The EX group had lower body fat percentage (14.6% ± 1.1% vs 23.3% ± 1.7%, P = 0.0002) and higher maximal oxygen uptake (53 ± 2 vs 34 ± 2, P < 0.0001) than CON. Glucose AUC did not differ between groups (P = 0.20). Insulin AUC was lower in EX (2.5 ± 0.5 vs 4.2 ± 1.2 μU·mL·1000 min, P = 0.02). No differences were observed between groups (EX and CON, respectively) for GLP-1 AUC (3.5 ± 0.7 vs 4.1 ± 1.1 pmol·min·100 L, P = 0.61) or GIP AUC (19.2 ± 1.4 vs 18.0 ± 1.4 pg·min·1000 mL; P = 0.56). In CON, insulin AUC was correlated with AUC for GLP-1 (r = 0.53, P = 0.05) and GIP (r = 0.71, P = 0.004), but no such correlations were observed in EX (both P ≥ 0.67). CONCLUSIONS Low postprandial insulin levels in lean exercise-trained individuals are not attributable to lower incretin hormone concentrations. However, exercise may decrease the dependency of postprandial insulin levels on incretin hormones.
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Affiliation(s)
- Edward P Weiss
- 1Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO; 2Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, MO; 3Department of Biology, Saint Louis University, St. Louis, MO; 4Department of Medicine, Salerno University Medical School, Salerno, ITALY; and 5CEINGE Biotecnologie Avanzate, Napoli, ITALY
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Andrisse S, Koehler RM, Chen JE, Patel GD, Vallurupalli VR, Ratliff BA, Warren DE, Fisher JS. Role of GLUT1 in regulation of reactive oxygen species. Redox Biol 2014; 2:764-71. [PMID: 25101238 PMCID: PMC4116627 DOI: 10.1016/j.redox.2014.03.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 03/19/2014] [Indexed: 12/16/2022] Open
Abstract
In skeletal muscle cells, GLUT1 is responsible for a large portion of basal uptake of glucose and dehydroascorbic acid, both of which play roles in antioxidant defense. We hypothesized that conditions that would decrease GLUT1-mediated transport would cause increased reactive oxygen species (ROS) levels in L6 myoblasts, while conditions that would increase GLUT1-mediated transport would result in decreased ROS levels. We found that the GLUT1 inhibitors fasentin and phloretin increased the ROS levels induced by antimycin A and the superoxide generator pyrogallol. However, indinavir, which inhibits GLUT4 but not GLUT1, had no effect on ROS levels. Ataxia telangiectasia mutated (ATM) inhibitors and activators, previously shown to inhibit and augment GLUT1-mediated transport, increased and decreased ROS levels, respectively. Mutation of an ATM target site on GLUT1 (GLUT1-S490A) increased ROS levels and prevented the ROS-lowering effect of the ATM activator doxorubicin. In contrast, expression of GLUT1-S490D lowered ROS levels during challenge with pyrogallol, prevented an increase in ROS when ATM was inhibited, and prevented the pyrogallol-induced decrease in insulin signaling and insulin-stimulated glucose transport. Taken together, the data suggest that GLUT1 plays a role in regulation of ROS and could contribute to maintenance of insulin action in the presence of ROS. Inhibition of GLUT1, but not inhibition of GLUT4, increases ROS levels in myoblasts. Mutation of an ATM target site on GLUT1 to alanine (GLUT1-S490A) increases ROS. The ATM activator doxorubicin decreases ROS except in cells that express GLUT1-S490A. Inhibition of ATM increases ROS except in cells transfected with GLUT1S490D. Expression of GLUT1-S490D protects cells against ROS-mediated insulin resistance.
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Affiliation(s)
- Stanley Andrisse
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Rikki M Koehler
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Joseph E Chen
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Gaytri D Patel
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Vivek R Vallurupalli
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Benjamin A Ratliff
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Daniel E Warren
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
| | - Jonathan S Fisher
- Department of Biology, Saint Louis University, 3507 Laclede Ave, St. Louis, MO 63103, USA
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Andrisse S, Patel GD, Chen JE, Webber AM, Spears LD, Koehler RM, Robinson-Hill RM, Ching JK, Jeong I, Fisher JS. ATM and GLUT1-S490 phosphorylation regulate GLUT1 mediated transport in skeletal muscle. PLoS One 2013; 8:e66027. [PMID: 23776597 PMCID: PMC3679034 DOI: 10.1371/journal.pone.0066027] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 05/04/2013] [Indexed: 12/24/2022] Open
Abstract
Objective The glucose and dehydroascorbic acid (DHA) transporter GLUT1 contains a phosphorylation site, S490, for ataxia telangiectasia mutated (ATM). The objective of this study was to determine whether ATM and GLUT1-S490 regulate GLUT1. Research Design and Methods L6 myoblasts and mouse skeletal muscles were used to study the effects of ATM inhibition, ATM activation, and S490 mutation on GLUT1 localization, trafficking, and transport activity. Results In myoblasts, inhibition of ATM significantly diminished cell surface GLUT1, glucose and DHA transport, GLUT1 externalization, and association of GLUT1 with Gα-interacting protein-interacting protein, C-terminus (GIPC1), which has been implicated in recycling of endosomal proteins. In contrast, ATM activation by doxorubicin (DXR) increased DHA transport, cell surface GLUT1, and the GLUT1/GIPC1 association. S490A mutation decreased glucose and DHA transport, cell surface GLUT1, and interaction of GLUT1 with GIPC1, while S490D mutation increased transport, cell surface GLUT1, and the GLUT1/GIPC1 interaction. ATM dysfunction or ATM inhibition reduced DHA transport in extensor digitorum longus (EDL) muscles and decreased glucose transport in EDL and soleus. In contrast, DXR increased DHA transport in EDL. Conclusions These results provide evidence that ATM and GLUT1-S490 promote cell surface GLUT1 and GLUT1-mediated transport in skeletal muscle associated with upregulation of the GLUT1/GIPC1 interaction.
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Affiliation(s)
- Stanley Andrisse
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Gaytri D. Patel
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Joseph E. Chen
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Andrea M. Webber
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Larry D. Spears
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Rikki M. Koehler
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Rona M. Robinson-Hill
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - James K. Ching
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Imju Jeong
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Jonathan S. Fisher
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
- * E-mail:
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Ching JK, Spears LD, Armon JL, Renth AL, Andrisse S, Collins RL, Fisher JS. Impaired insulin-stimulated glucose transport in ATM-deficient mouse skeletal muscle. Appl Physiol Nutr Metab 2012; 38:589-96. [PMID: 23724874 DOI: 10.1139/apnm-2012-0175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
There are reports that ataxia telangiectasia mutated (ATM) plays a role in insulin-stimulated Akt phosphorylation, although this is not the case in some cell types. Because Akt plays a key role in insulin signaling, which leads to glucose transport in skeletal muscle, the predominant tissue in insulin-stimulated glucose disposal, we examined whether insulin-stimulated Akt phosphorylation and (or) glucose transport would be decreased in skeletal muscle of mice lacking functional ATM, compared with muscle from wild-type mice. We found that in vitro insulin-stimulated Akt phosphorylation was normal in soleus muscle from mice with 1 nonfunctional allele of ATM (ATM+/-) and from mice with 2 nonfunctional alleles (ATM-/-). However, insulin did not stimulate glucose transport or the phosphorylation of AS160 in ATM-/- soleus. ATM protein level was markedly higher in wild-type extensor digitorum longus (EDL) than in wild-type soleus. In EDL from ATM-/- mice, insulin did not stimulate glucose transport. However, in contrast to findings for soleus, insulin-stimulated Akt phosphorylation was blunted in ATM-/- EDL, concomitant with a tendency for insulin-stimulated phosphatidylinositol 3-kinase activity to be decreased. Together, the findings suggest that ATM plays a role in insulin-stimulated glucose transport at the level of AS160 in muscle comprised of slow and fast oxidative-glycolytic fibers (soleus) and at the level of Akt in muscle containing fast glycolytic fibers (EDL).
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Affiliation(s)
- James Kain Ching
- Department of Biology, Saint Louis University, 3507 Laclede Ave., St. Louis, MO 63103, USA
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Ching JK, Luebbert SH, Collins RL, Zhang Z, Marupudi N, Banerjee S, Hurd RD, Ralston L, Fisher JS. Ataxia telangiectasia mutated impacts insulin-like growth factor 1 signalling in skeletal muscle. Exp Physiol 2012; 98:526-35. [PMID: 22941977 DOI: 10.1113/expphysiol.2012.066357] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Reports that ataxia telangiectasia mutated (ATM) is required for full activation of Akt raise the hypothesis that ATM plays a role in insulin-like growth factor 1 (IGF-1) signalling through the Akt/mammalian target of rapamycin (mTOR) pathway. Differentiated C2C12 cells harbouring either ATM-targeting short hairpin RNA (shRNA) or non-targeting shRNA and myotubes from a C2C12 lineage previously exposed to empty vector lentivirus were incubated in the presence or absence of 10 nm IGF-1 followed by Western blot analysis. Parallel experiments were performed in isolated soleus muscles from mice expressing only one functional ATM allele (ATM(+/-)) compared with muscles from wild-type (ATM(+/+)) mice. Insulin-like growth factor 1 increased phosphorylation of Akt S473, Akt T308 and p70 S6 kinase (S6K) in myotubes expressing non-targeting shRNA and in empty vector controls, but the IGF-1 effects were significantly reduced in myotubes with shRNA-mediated ATM knockdown. Likewise, IGF-1-stimulated phosphorylation of Akt S473, Akt T308, mTOR and S6K was lower in isolated soleus muscles from ATM(+/-) mice compared with muscles from ATM(+/+) mice. The ATM inhibitor KU55933 prevented stimulation of S6K phosphorylation in C2C12 myotubes exposed to IGF-1, suggesting that decreased IGF-1 action is not limited to chronic conditions of decreased ATM function. Stimulation of insulin receptor substrate 1 tyrosine 612 phosphorylation by IGF-1 was unaffected by ATM deficiency, though IGF-1 phosphatidylinositol 3-kinase activity tended to be lower in muscle from ATM haploinsufficient mice compared with wild-type muscle. The data suggest that ATM is a modulator of IGF-1 signalling downstream of insulin receptor substrate 1 in skeletal muscle.
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Affiliation(s)
- James Kain Ching
- Department of Biology, Saint Louis University, St Louis, MO 63103, USA
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Andrisse S, Patel GD, Chen JE, Webber AM, Spears LD, Fisher JS. Regulation of GLUT1‐mediated glucose and dehydroascorbic acid (DHA) transport. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1078.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Strickland VJ, Fisher JS, Williams HG, Potts WT, Hepworth GW. Sensory quality of meat from lambs fed garlic. Meat Sci 2011; 88:590-3. [PMID: 21345600 DOI: 10.1016/j.meatsci.2011.01.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 01/18/2011] [Accepted: 01/28/2011] [Indexed: 10/18/2022]
Abstract
The objective of this study was to determine whether the inclusion of garlic in a ration would have a negative impact on the flavour of lamb. The study used meat from 31 Merino wether lambs fed diets with varying levels of garlic (0%, 1.8% and 3.6%) for 10 weeks. Cooked samples of meat from the lambs were assessed for flavour and acceptability as lamb by an untrained consumer panel. There was no difference (P>0.05) between the treatments in flavour score, but the 3.6% garlic treatment group scored significantly higher in terms of acceptability as lamb (P<0.05) and was commented on positively by the panellists more frequently than the meat from any other treatment (P<0.05). These results suggest that the inclusion of garlic into the animals' feed did not have a negative impact on the flavour of the lamb and, at the high rate (3.6%), made the meat more acceptable to the panellists.
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Affiliation(s)
- V J Strickland
- Muresk Campus, School of Agriculture and Environment, Curtin University, Locked Bag 1, Northam, 6401 Western Australia, Australia.
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Abstract
Serum starvation is a common cell culture procedure for increasing cellular response to insulin, though the mechanism for the serum starvation effect is not understood. We hypothesized that factors known to potentiate insulin action [e.g., AMP-activated protein kinase (AMPK) and p38] or to be involved in insulin signaling leading to glucose transport [e.g., Akt, PKCζ, AS160, and ataxia telangiectasia mutated (ATM)] would be phosphorylated during serum starvation and would be responsible for increased insulin action after serum starvation. L6 myotubes were incubated in serum-containing or serum-free medium for 3 h. Levels of phosphorylated AMPK, Akt, and ATM were greater in serum-starved cells than in control cells. Serum starvation did not affect p38, PKCζ, or AS160 phosphorylation or insulin-stimulated Akt or AS160 phosphorylation. Insulin had no effect on glucose transport in control cells but caused an increase in glucose uptake for serum-starved cells that was preventable by compound C (an AMPK inhibitor), by expression of dominant negative AMPK (AMPK-DN), and by KU55933 (an ATM inhibitor). ATM protein levels increased during serum starvation, and this increase in ATM was prevented by compound C and AMPK-DN. Thus, it appears that AMPK is required for the serum starvation-related increase in insulin-stimulated glucose transport, with ATM as a possible downstream effector.
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Affiliation(s)
- James Kain Ching
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103, USA
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McDonald TM, Patel AY, Fisher JS. Decreased aconitase and cytochrome
c
oxidase activity in skeletal muscle of ATM‐deficient mice. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1001.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Robinson‐Hill R, Ching JK, Fisher JS. LiCl causes an acute decrease in ataxia telangiectasia mutated (ATM) protein levels in L6 myotubes. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.lb675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jeong I, Patel AY, Zhang Z, Patil PB, Nadella ST, Nair S, Ralston L, Hoormann JK, Fisher JS. Role of ataxia telangiectasia mutated in insulin signalling of muscle-derived cell lines and mouse soleus. Acta Physiol (Oxf) 2010; 198:465-75. [PMID: 20003097 DOI: 10.1111/j.1748-1716.2009.02069.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIM Ataxia telangiectasia mutated (ATM) reportedly plays a role in insulin-stimulated activation of Akt in some cell types but not in others. The role of ATM in insulin signalling has not been firmly resolved for skeletal muscle cells, for which Akt phosphorylation is a pivotal step in stimulation of glucose transport. Accordingly, our aim was to determine the role of ATM in insulin effects for cell lines derived from skeletal muscle and for skeletal muscle. METHODS We examined insulin effects in L6 myotubes, mouse soleus, C2C12 myotubes and differentiated rhabdomyosarcoma (RD) cells in the presence and absence of a low concentration (1 microm) of the ATM inhibitor KU55933. We also compared insulin signalling in C2C12 cells expressing shRNA against ATM and control cell lines (empty vector; cells expressing non-targeting shRNA). RESULTS In L6 myotubes and mouse soleus muscle, KU55933 inhibited insulin-stimulated phosphorylation of the 160 kDa substrate of Akt (AS160) despite no effect on Akt. In contrast, KU55933 prevented insulin-stimulated Akt phosphorylation in C2C12 myotubes. Furthermore, C2C12 myotubes expressing shRNA against ATM displayed reduced insulin-stimulated Akt phosphorylation compared to controls. KU55933 also decreased insulin-stimulated Akt phosphorylation in differentiated RD cells. CONCLUSION These model-dependent differences in the role of ATM in insulin action demonstrate a role of ATM in insulin-stimulated phosphorylation of Akt (in C2C12 and RD cells) but also allow the elucidation of a novel, Akt-independent role of ATM (in L6 myotubes and mouse soleus, at the level of AS160) in insulin signalling.
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Affiliation(s)
- I Jeong
- Department of Biology, Saint Louis University, MO 63103, USA
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Ching JK, Armon JL, Renth A, Collins RL, Fisher JS. ATM plays a role in insulin‐stimulated phosphorylation of AS160 independent of Akt in mouse soleus muscle. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1046.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Allyson Renth
- Department of BiologySaint Louis UniversitySt. LouisMO
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Spears LD, Qin C, Zhang Z, Ralston L, Fisher JS. The ATM activator chloroquine stimulates phosphorylation of AMP activated protein kinase (AMPK) and acetyl CoA‐carboxylase (ACC) independent of ATM. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.lb674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Charles Qin
- Department of BiologySaint Louis UniversitySt. LouisMO
| | | | - Lyle Ralston
- Research BiotechnologySigma‐AldrichSt. LouisMO
- Currently with Monsanto CompanySt. LouisMO
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Kurian SM, Heilman R, Mondala TS, Nakorchevsky A, Hewel JA, Campbell D, Robison EH, Wang L, Lin W, Gaber L, Solez K, Shidban H, Mendez R, Schaffer RL, Fisher JS, Flechner SM, Head SR, Horvath S, Yates JR, Marsh CL, Salomon DR. Biomarkers for early and late stage chronic allograft nephropathy by proteogenomic profiling of peripheral blood. PLoS One 2009; 4:e6212. [PMID: 19593431 PMCID: PMC2703807 DOI: 10.1371/journal.pone.0006212] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 06/04/2009] [Indexed: 12/13/2022] Open
Abstract
Background Despite significant improvements in life expectancy of kidney transplant patients due to advances in surgery and immunosuppression, Chronic Allograft Nephropathy (CAN) remains a daunting problem. A complex network of cellular mechanisms in both graft and peripheral immune compartments complicates the non-invasive diagnosis of CAN, which still requires biopsy histology. This is compounded by non-immunological factors contributing to graft injury. There is a pressing need to identify and validate minimally invasive biomarkers for CAN to serve as early predictors of graft loss and as metrics for managing long-term immunosuppression. Methods We used DNA microarrays, tandem mass spectroscopy proteomics and bioinformatics to identify genomic and proteomic markers of mild and moderate/severe CAN in peripheral blood of two distinct cohorts (n = 77 total) of kidney transplant patients with biopsy-documented histology. Findings Gene expression profiles reveal over 2400 genes for mild CAN, and over 700 for moderate/severe CAN. A consensus analysis reveals 393 (mild) and 63 (moderate/severe) final candidates as CAN markers with predictive accuracy of 80% (mild) and 92% (moderate/severe). Proteomic profiles show over 500 candidates each, for both stages of CAN including 302 proteins unique to mild and 509 unique to moderate/severe CAN. Conclusions This study identifies several unique signatures of transcript and protein biomarkers with high predictive accuracies for mild and moderate/severe CAN, the most common cause of late allograft failure. These biomarkers are the necessary first step to a proteogenomic classification of CAN based on peripheral blood profiling and will be the targets of a prospective clinical validation study.
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Affiliation(s)
- Sunil M. Kurian
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America
| | | | - Tony S. Mondala
- DNA Microarray Core, The Scripps Research Institute, La Jolla, California, United States of America
| | - Aleksey Nakorchevsky
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Johannes A. Hewel
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Daniel Campbell
- DNA Microarray Core, The Scripps Research Institute, La Jolla, California, United States of America
| | - Elizabeth H. Robison
- DNA Microarray Core, The Scripps Research Institute, La Jolla, California, United States of America
| | - Lin Wang
- Department of Biostatistics, University of California, Los Angeles, California, United States of America
| | - Wen Lin
- Department of Biostatistics, University of California, Los Angeles, California, United States of America
| | - Lillian Gaber
- The Texas Medical Center, Houston, Texas, United States of America
| | - Kim Solez
- University of Alberta, Edmonton, Canada
| | - Hamid Shidban
- St. Vincent Medical Center, Los Angeles, California, United States of America
| | - Robert Mendez
- St. Vincent Medical Center, Los Angeles, California, United States of America
| | - Randolph L. Schaffer
- Scripps Center for Organ and Cell Transplantation, Scripps Health, La Jolla, California, United States of America
| | - Jonathan S. Fisher
- Scripps Center for Organ and Cell Transplantation, Scripps Health, La Jolla, California, United States of America
| | - Stuart M. Flechner
- Glickman Urological Institute, The Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Steve R. Head
- DNA Microarray Core, The Scripps Research Institute, La Jolla, California, United States of America
| | - Steve Horvath
- Department of Biostatistics, University of California, Los Angeles, California, United States of America
| | - John R. Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Christopher L. Marsh
- Scripps Center for Organ and Cell Transplantation, Scripps Health, La Jolla, California, United States of America
| | - Daniel R. Salomon
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Center for Organ and Cell Transplantation, Scripps Health, La Jolla, California, United States of America
- * E-mail:
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Weiss EP, Royer NK, Fisher JS, Holloszy JO, Fontana L. Attenuated Postprandial Insulin Concentrations With Endurance Training Are Not Mediated By Reductions In Incretin Hormones. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000354122.11055.58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ching JK, Luebbert SH, Zhang Z, Marupudi N, Banerjee S, Hurd R, Collins RL, Ralston L, Fisher JS. Ataxia telangiectasia mutated (ATM) is required in insulin‐like growth factor‐1 (IGF‐1) signaling through the PI3K/Akt pathway. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.782.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | - Robin Hurd
- Dept. of BiologySaint Louis UniversitySt. LouisMO
| | | | - Lyle Ralston
- Research Biotechnology, Sigma‐AldrichSt. LouisMO
- currently at Monsanto CompanySt. LouisMO
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Lewis LR, Davis J, Akinola A, Fisher JS. Inhibition of ataxia telangiectasia mutated (ATM) prevents the prolonged increase in phosphorylation of Akt substrate of 160 kDa (AS160) subsequent to activation of the AMP‐activated protein kinase (AMPK). FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.782.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Spears LD, Hobbs SB, Zhang Z, Ralston L, Liang CA, Royer NK, Fisher JS. Chloroquine and resveratrol stimulate ATM‐independent phosphorylation of AMPK and AKT. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.782.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Lyle Ralston
- Research Biotechnology, Sigma‐AldrichSt. LouisMO
- currently at Monsanto CompanySt. LouisMO
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Spears LD, Tran AV, Fisher JS. Chloroquine stimulates phosphorylation of the AMP‐activated protein kinase (AMPK) and Akt. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.959.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Affiliation(s)
| | - Pooja Rajguru
- Department of BiologySaint Louis UniversitySt. LouisMO
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Patil PB, Minteer SD, Mielke AA, Lewis LR, Casmaer CA, Barrientos EJ, Ju JS, Smith JL, Fisher JS. Malonyl coenzyme A affects insulin-stimulated glucose transport in myotubes. Arch Physiol Biochem 2007; 113:13-24. [PMID: 17522981 DOI: 10.1080/13813450701318542] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
There seems to be an association between increased concentrations of malonyl coenzyme A (malonyl CoA) in skeletal muscle and diabetes and/or insulin resistance. The purpose of the current study was to test the hypothesis that treatments designed to manipulate malonyl CoA concentrations would affect insulin-stimulated glucose transport in cultured C2C12 myotubes. We assessed glucose transport after polyamine-mediated delivery of malonyl CoA to myotubes, after incubation with dichloroacetate (which reportedly increases malonyl CoA levels), or after exposure of myotubes to 2-bromopalmitate, a carnitine palmitoyl transferase I inhibitor. All three of these treatments prevented stimulation of glucose transport by insulin. We also assayed glucose transport after 30 min of inhibition of acetyl coenzyme A carboxylase (ACC), the enzyme which catalyzes the production of malonyl CoA. Three unrelated ACC inhibitors (diclofop, clethodim, and Pfizer CP-640186) all enhanced insulin-stimulated glucose transport. However, none of the treatments designed to manipulate malonyl CoA concentrations altered markers of proximal insulin signaling through Akt. The findings support the hypothesis that acute changes in malonyl CoA concentrations affect insulin action in muscle cells but suggest that the effects do not involve alterations in proximal insulin signaling.
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Affiliation(s)
- P B Patil
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
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Ju JS, Gitcho MA, Casmaer CA, Patil PB, Han DG, Spencer SA, Fisher JS. Potentiation of insulin-stimulated glucose transport by the AMP-activated protein kinase. Am J Physiol Cell Physiol 2006; 292:C564-72. [PMID: 16870829 PMCID: PMC1868576 DOI: 10.1152/ajpcell.00269.2006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Data from the use of activators and inhibitors of the AMP-activated protein kinase (AMPK) suggest that AMPK increases sensitivity of glucose transport to stimulation by insulin in muscle cells. We assayed insulin action after adenoviral (Ad) transduction of constitutively active (CA; a truncated form of AMPKalpha(1)) and dominant-negative (DN; which depletes endogenous AMPKalpha) forms of AMPKalpha (Ad-AMPKalpha-CA and Ad-AMPKalpha-DN, respectively) into C(2)C(12) myotubes. Compared with control (Ad-green fluorescent protein), Ad-AMPK-CA increased the ability of insulin to stimulate glucose transport. The increased insulin action in cells expressing AMPK-CA was suppressed by compound C (an AMPK inhibitor). Exposure of cells to 5-aminoimidazole-4-carboxamide-1beta-D-ribofuranoside (an AMPK activator) increased insulin action in uninfected myotubes and myotubes transduced with green fluorescent protein but not in Ad-AMPK-DN-infected myotubes. In Ad-AMPK-CA-transduced cells, serine phosphorylation of insulin receptor substrate 1 was decreased at a mammalian target of rapamycin (or p70 S6 kinase) target site that has been reported to be associated with insulin resistance. These data suggest that, in myotubes, activated AMPKalpha(1) is sufficient to increase insulin action and that the presence of functional AMPKalpha is required for 5-aminoimidazole-4-carboxamide-1beta,D-ribofuranoside-related increases in insulin action.
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Affiliation(s)
- Jeong-Sun Ju
- Department of Biology, Saint Louis University, 3507 Laclede Avenue, St. Louis, MO 63103, USA
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Abstract
Levodopa reportedly inhibits insulin action in skeletal muscle. Here we show that C2C12 myotubes produce levodopa and that insulin-stimulated glucose transport is enhanced when endogenous levodopa is depleted. Exogenous levodopa prevented the stimulation of glucose transport by insulin (P < 0.05) and increased cAMP concentrations (P < 0.05). The decrease in insulin-stimulated glucose transport caused by levodopa was attenuated by propranolol (a beta-adrenergic antagonist) and prevented by NSD-1015 (NSD), an inhibitor of DOPA decarboxylase (DDC; converts levodopa to dopamine). Propranolol and NSD both prevented levodopa-related increases in [cAMP]. However, the effects of levodopa were unlikely to be dependent on the conversion of levodopa to catecholamines because we could detect neither DDC in myotubes nor catecholamines in media after incubation of myotubes with levodopa. The data suggest the possibility of novel autocrine beta-adrenergic action in C2C12 myotubes in which levodopa, produced by myotubes, could have hormone-like effects that impinge on glucose metabolism.
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Affiliation(s)
- Jill L Smith
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
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Fisher JS. Potential Role of the AMP-activated Protein Kinase in Regulation of Insulin Action. Cellscience 2006; 2:68-81. [PMID: 18049717 PMCID: PMC2099311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Because of the predominant role of skeletal muscle in insulin-stimulated clearance of blood glucose, understanding mechanisms for increasing the ability of muscle to respond to insulin could potentially lead to novel strategies for treatment or prevention of diabetes. Recently, the AMP activated protein kinase (AMPK) has emerged as a promising candidate for potentiation of insulin action. Several antidiabetic drugs have been shown to activate AMPK, cellular stresses such as exercise that increase AMPK activity also increase insulin action, and several downstream targets of AMPK seem to be involved in regulation of insulin action. Although the picture is currently incomplete, it seems possible that AMPK or one of its effectors is a positive regulator of insulin-stimulated glucose transport. In addition to discussion of the latest literature regarding AMPK and insulin action, this review includes a non-technical summary for students, academics from other fields, interested professionals, and the general public.
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Affiliation(s)
- Jonathan S Fisher
- Department of Biology, 3507 Laclede Ave., Saint Louis University St. Louis, MO 63103 USA
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Abstract
We hypothesized that AMP-activated protein kinase-related kinase 5 (ARK5)/novel kinase family 1 (NUAK1), an AMP-activated protein kinase (AMPK)-related kinase that has been found to be stimulated by protein kinase B (Akt), would be expressed in rat skeletal muscle and activated by electrically elicited contractions, 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR), or insulin. We verified expression of ARK5 in muscle through RT-PCR and Western blot. Cross-reactivity of ARK5 immunoprecipitates with antibodies against phospho-AMPK was increased by approximately 30% by muscle contractions and approximately 60% by incubation of muscle with AICAR. AMPK was not detected in the ARK5 immunoprecipitates. Despite the apparent increase in phosphorylation of ARK5 at a site essential to its activation, neither contractions nor AICAR increased ARK5 activity. For muscles from animals injected with saline or insulin, we probed nonimmunoprecipitated samples in sequence for phosphotyrosine (P-Tyr), ARK5, and phosphorylated substrates of Akt (P-AS) and found that the ARK5 band could be precisely superimposed on phosphoprotein bands from the P-Tyr and P-AS blots. In the band corresponding to ARK5, insulin increased P-Tyr content by approximately 45% and cross-reactivity with the antibody against P-AS by approximately threefold. We also detected ARK5 in phosphotyrosine immunoprecipitates. Our data suggest that increased phosphorylation of ARK5 by muscle contractions or exposure to AICAR is insufficient to activate ARK5 in skeletal muscle, suggesting that some other modification (e.g., phosphorylation on tyrosine or by Akt) may be necessary to its activity in muscle.
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Affiliation(s)
- Jonathan S Fisher
- Dept. of Biology, Saint Louis University, 3507 Laclede Avenue, St. Louis, MO 63103, USA.
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Abstract
Skeletal muscle serves as the body's major glutamine repository, and releases glutamine at enhanced rates during diabetes, but whether all muscles are equally affected is unknown. System N(m) activity mediates most trans-sarcolemmal glutamine movement, and although two System N (SN) isoforms have been identified (SN1/sodium-coupled neutral amino acid transporter or System N and A transporters [SNAT]-3; and SN2/SNAT5), their expression in skeletal muscle remains controversial. Here, the impact of Type I diabetes on glutamine uptake and System N transporter expression were examined in fast- and slow-twitch skeletal muscle from spontaneously diabetic (BB/Wor-DP) rats. Net glutamine uptake in fast-twitch fibers was decreased 75%-95%, but enhanced more than 2-fold in slow-twitch muscle from diabetic animals relative to nondiabetic controls. Both SNAT3 and SNAT5 mRNA were expressed in both muscle fiber types and their abundance was unaffected by diabetes. This represents the first report of differential fiber-specific effects of diabetes on skeletal muscle glutamine transport and the co-expression of distinct System N transporters in skeletal muscle.
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Affiliation(s)
- Marie C Onan
- Department of Biology, Saint Louis University, St. Louis, MO 63103-2010, USA
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49
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Abstract
Sensitivity of glucose transport to stimulation by insulin has been shown to occur concomitant with activation of the AMP-activated protein kinase (AMPK) in skeletal muscle, suggesting a role of AMPK in regulation of insulin action. The purpose of the present study was to evaluate a possible role of AMPK in potentiation of insulin action in muscle cells. The experimental model involved insulin-responsive C2C12 myotubes that exhibit a twofold increase in glucose transport in the presence of insulin. Treatment of myotubes with the AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR), followed by a 2-h recovery, augmented the ability of insulin to stimulate glucose transport. Similarly, incubation in hyperosmotic medium, another AMPK-activating treatment, acted synergistically with insulin to stimulate glucose transport. Furthermore, the increase in insulin action caused by hyperosmotic stress was prevented by inclusion of compound C, an AMPK inhibitor, in hyperosmotic medium. In addition, iodotubercidin, a general kinase inhibitor that is effective against AMPK, also prevented the combined effects of insulin and hyperosmotic stress on glucose transport. The new information provided by these data is that previously reported AICAR effects on insulin action are generalizable to myotubes, hyperosmotic stress and insulin synergistically increase glucose transport, and AMPK appears to mediate potentiation of insulin action.
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Affiliation(s)
- Jill L Smith
- Dept. of Biology, Saint Louis Univ., 3507 Laclede Ave., St. Louis, MO 63103, USA
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Abstract
The purpose of this study was to investigate the potential role of creatine in GLUT4 gene expression in rat skeletal muscle. Female Wistar rats were fed normal rat chow (controls) or chow containing 2% creatine monohydrate ad libitum for 3 wk. GLUT4 protein levels of creatine-fed rats were significantly increased in extensor digitorum longus (EDL), triceps, and epitrochlearis muscles compared with muscles from controls (P < 0.05), and triceps GLUT4 mRNA levels were approximately 100% greater in triceps muscles from creatine-fed rats than in muscles from controls (P < 0.05). In epitrochlearis muscles from creatine-fed animals, glycogen content was approximately 40% greater (P < 0.05), and insulin-stimulated glucose transport rates were higher (P < 0.05) than in epitrochlearis muscles from controls. Despite no changes in [ATP], [creatine], [phosphocreatine], or [AMP], creatine feeding increased AMP-activated protein kinase (AMPK) phosphorylation by 50% in rat EDL muscle (P < 0.05). Creatinine content of EDL muscle was almost twofold higher for creatine-fed animals than for controls (P < 0.05). Creatine feeding increased protein levels of myocyte enhancer factor 2 (MEF2) isoforms MEF2A ( approximately 70%, P < 0.05), MEF2C ( approximately 60%, P < 0.05), and MEF2D ( approximately 90%, P < 0.05), which are transcription factors that regulate GLUT4 expression, in creatine-fed rat EDL muscle nuclear extracts. Electrophoretic mobility shift assay showed that DNA binding activity of MEF2 was increased by approximately 40% (P < 0.05) in creatine-fed rat EDL compared with controls. Our data suggest that creatine feeding enhances the nuclear content and DNA binding activity of MEF2 isoforms, which is concomitant with an increase in GLUT4 gene expression.
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Affiliation(s)
- Jeong-Sun Ju
- Dept. of Biology, Saint Louis University, 3507 Laclede Avenue, St. Louis, MO 63103, USA
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