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Draicchio F, Behrends V, Tillin NA, Hurren NM, Sylow L, Mackenzie R. Involvement of the extracellular matrix and integrin signalling proteins in skeletal muscle glucose uptake. J Physiol 2022; 600:4393-4408. [PMID: 36054466 PMCID: PMC9826115 DOI: 10.1113/jp283039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/03/2022] [Indexed: 01/11/2023] Open
Abstract
Whole-body euglycaemia is partly maintained by two cellular processes that encourage glucose uptake in skeletal muscle, the insulin- and contraction-stimulated pathways, with research suggesting convergence between these two processes. The normal structural integrity of the skeletal muscle requires an intact actin cytoskeleton as well as integrin-associated proteins, and thus those structures are likely fundamental for effective glucose uptake in skeletal muscle. In contrast, excessive extracellular matrix (ECM) remodelling and integrin expression in skeletal muscle may contribute to insulin resistance owing to an increased physical barrier causing reduced nutrient and hormonal flux. This review explores the role of the ECM and the actin cytoskeleton in insulin- and contraction-mediated glucose uptake in skeletal muscle. This is a clinically important area of research given that defects in the structural integrity of the ECM and integrin-associated proteins may contribute to loss of muscle function and decreased glucose uptake in type 2 diabetes.
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Affiliation(s)
- Fulvia Draicchio
- School of Life and Health SciencesWhitelands CollegeUniversity of RoehamptonLondonUK
| | - Volker Behrends
- School of Life and Health SciencesWhitelands CollegeUniversity of RoehamptonLondonUK
| | - Neale A. Tillin
- School of Life and Health SciencesWhitelands CollegeUniversity of RoehamptonLondonUK
| | - Nicholas M. Hurren
- School of Life and Health SciencesWhitelands CollegeUniversity of RoehamptonLondonUK
| | - Lykke Sylow
- Molecular Metabolism in Cancer & Ageing Research GroupDepartment of Biomedical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Richard Mackenzie
- School of Life and Health SciencesWhitelands CollegeUniversity of RoehamptonLondonUK
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2
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Wasserman DH. Insulin, Muscle Glucose Uptake, and Hexokinase: Revisiting the Road Not Taken. Physiology (Bethesda) 2022; 37:115-127. [PMID: 34779282 PMCID: PMC8977147 DOI: 10.1152/physiol.00034.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/05/2021] [Accepted: 11/07/2021] [Indexed: 12/25/2022] Open
Abstract
Research conducted over the last 50 yr has provided insight into the mechanisms by which insulin stimulates glucose transport across the skeletal muscle cell membrane Transport alone, however, does not result in net glucose uptake as free glucose equilibrates across the cell membrane and is not metabolized. Glucose uptake requires that glucose is phosphorylated by hexokinases. Phosphorylated glucose cannot leave the cell and is the substrate for metabolism. It is indisputable that glucose phosphorylation is essential for glucose uptake. Major advances have been made in defining the regulation of the insulin-stimulated glucose transporter (GLUT4) in skeletal muscle. By contrast, the insulin-regulated hexokinase (hexokinase II) parallels Robert Frost's "The Road Not Taken." Here the case is made that an understanding of glucose phosphorylation by hexokinase II is necessary to define the regulation of skeletal muscle glucose uptake in health and insulin resistance. Results of studies from different physiological disciplines that have elegantly described how hexokinase II can be regulated are summarized to provide a framework for potential application to skeletal muscle. Mechanisms by which hexokinase II is regulated in skeletal muscle await rigorous examination.
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Affiliation(s)
- David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
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3
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Williams MJ, Alsehli AM, Gartner SN, Clemensson LE, Liao S, Eriksson A, Isgrove K, Thelander L, Khan Z, Itskov PM, Moulin TC, Ambrosi V, Al-Sabri MH, Lagunas-Rangel FA, Olszewski PK, Schiöth HB. The Statin Target Hmgcr Regulates Energy Metabolism and Food Intake through Central Mechanisms. Cells 2022; 11:cells11060970. [PMID: 35326421 PMCID: PMC8946516 DOI: 10.3390/cells11060970] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 02/04/2023] Open
Abstract
The statin drug target, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), is strongly linked to body mass index (BMI), yet how HMGCR influences BMI is not understood. In mammals, studies of peripheral HMGCR have not clearly identified a role in BMI maintenance and, despite considerable central nervous system expression, a function for central HMGCR has not been determined. Similar to mammals, Hmgcr is highly expressed in the Drosophila melanogaster brain. Therefore, genetic and pharmacological studies were performed to identify how central Hmgcr regulates Drosophila energy metabolism and feeding behavior. We found that inhibiting Hmgcr, in insulin-producing cells of the Drosophila pars intercerebralis (PI), the fly hypothalamic equivalent, significantly reduces the expression of insulin-like peptides, severely decreasing insulin signaling. In fact, reducing Hmgcr expression throughout development causes decreased body size, increased lipid storage, hyperglycemia, and hyperphagia. Furthermore, the Hmgcr induced hyperphagia phenotype requires a conserved insulin-regulated α-glucosidase, target of brain insulin (tobi). In rats and mice, acute inhibition of hypothalamic Hmgcr activity stimulates food intake. This study presents evidence of how central Hmgcr regulation of metabolism and food intake could influence BMI.
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Affiliation(s)
- Michael J. Williams
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Ahmed M. Alsehli
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
- Faculty of Medicine, King Abdulaziz University and Hospital, Al Ehtifalat St., Jeddah 21589, Saudi Arabia
| | - Sarah N. Gartner
- Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand; (S.N.G.); (K.I.); (P.K.O.)
| | - Laura E. Clemensson
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Sifang Liao
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Anders Eriksson
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Kiriana Isgrove
- Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand; (S.N.G.); (K.I.); (P.K.O.)
| | - Lina Thelander
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Zaid Khan
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences (SLU), Sundsvägen 14, 230 53 Alnarp, Sweden
| | - Pavel M. Itskov
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Thiago C. Moulin
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Valerie Ambrosi
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Mohamed H. Al-Sabri
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Francisco Alejandro Lagunas-Rangel
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
| | - Pawel K. Olszewski
- Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand; (S.N.G.); (K.I.); (P.K.O.)
| | - Helgi B. Schiöth
- Functional Pharmacology and Neuroscience, Department of Surgical Sciences, Uppsala University, 751 24 Uppsala, Sweden; (M.J.W.); (A.M.A.); (L.E.C.); (S.L.); (A.E.); (L.T.); (Z.K.); (P.M.I.); (T.C.M.); (V.A.); (M.H.A.-S.); (F.A.L.-R.)
- Correspondence:
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4
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Rugo HS, Lacouture ME, Goncalves MD, Masharani U, Aapro MS, O'Shaughnessy JA. A multidisciplinary approach to optimizing care of patients treated with alpelisib. Breast 2022; 61:156-167. [PMID: 35016012 PMCID: PMC8749445 DOI: 10.1016/j.breast.2021.12.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/23/2021] [Accepted: 12/26/2021] [Indexed: 12/20/2022] Open
Abstract
PURPOSE The oral, α-specific phosphatidylinositol-3-kinase (PI3Kα) inhibitor alpelisib is the first PI3K inhibitor approved for the treatment of advanced breast cancer. As alpelisib is a relatively new therapeutic option, specific guidance and a multidisciplinary approach are needed to provide optimal patient care. The primary objective of this manuscript is to provide comprehensive guidance on minimizing and managing adverse events (AEs) for patients with advanced breast cancer who are receiving alpelisib. METHODS Clinical studies, prescribing information, published literature, and relevant guidelines were reviewed to provide recommendations on the prevention and management of alpelisib-associated AEs. RESULTS The most common AEs associated with alpelisib in the phase 3 SOLAR-1 trial were hyperglycemia and rash (which are considered on-target effects of PI3Kα inhibition) and gastrointestinal AEs, including diarrhea, nausea, and decreased appetite. These AEs require regular monitoring, early recognition, and prompt initiation of appropriate treatment. In addition, there are effective strategies to reduce the onset and severity of frequently observed AEs-in particular, onset of hyperglycemia and rash may be reduced by lifestyle changes (such as reduced intake of carbohydrates and regular exercise) and antihistamine prophylaxis, respectively. To reduce risk of severe hyperglycemia, it is essential to achieve adequate glycemic control prior to initiation of alpelisib treatment. CONCLUSION Overall, alpelisib-associated AEs are generally manageable with prompt recognition, regular monitoring, and appropriate intervention, preferably with a multidisciplinary approach.
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Affiliation(s)
- Hope S Rugo
- Department of Medicine (Hematology/Oncology), University of California San Francisco Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, USA.
| | - Mario E Lacouture
- Dermatology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Marcus D Goncalves
- Division of Endocrinology, Weill Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
| | - Umesh Masharani
- Department of Medicine (Endocrinology), University of California San Francisco, San Francisco, CA, USA.
| | - Matti S Aapro
- Department of Oncology, Genolier Cancer Centre, Clinique de Genolier, Genolier, Switzerland.
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5
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Goncalves MD, Farooki A. Management of Phosphatidylinositol-3-Kinase Inhibitor-Associated Hyperglycemia. Integr Cancer Ther 2022; 21:15347354211073163. [PMID: 35075945 PMCID: PMC8793384 DOI: 10.1177/15347354211073163] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/06/2021] [Accepted: 12/22/2021] [Indexed: 11/15/2022] Open
Abstract
Phosphatidylinositol-3-kinase (PI3K) pathway hyperactivation has been associated with the development of cancer and treatment resistance. PI3K inhibitors are now used to treat hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-), PIK3CA-mutated advanced breast cancer. Hyperglycemia, a frequently observed adverse event with PI3K inhibitors (PI3Ki), is regarded as an on-target effect because inhibition of the PI3K pathway has been shown to decrease glucose transport and increase glycogenolysis and gluconeogenesis. PI3Ki-induced hyperglycemia results in a compensatory increase in insulin release, which has been shown to reduce the efficacy of treatment by reactivating the PI3K pathway in preclinical models. Patients with an absolute or relative deficiency in insulin, and those with insulin resistance or pancreatic dysfunction, may experience exacerbated or prolonged hyperglycemia. Therefore, the effective management of PI3Ki-associated hyperglycemia depends on early identification of patients at risk, frequent monitoring to allow prompt recognition of hyperglycemia and its sequelae, and initiating appropriate management strategies. Risk factors for the development of hyperglycemia include older age (≥75 years), overweight/obese at baseline, and family history of diabetes. Consultation with an endocrinologist is recommended for patients considered high risk. The management of PI3Ki-induced hyperglycemia requires an integrative approach that combines diets low in carbohydrates and glucose-lowering medications. Medications that do not affect the PI3K pathway are preferred as the primary and secondary agents for the management of hyperglycemia. These include metformin, sodium-glucose co-transporter 2 inhibitors, thiazolidinediones, and α-glucosidase inhibitors. Insulin should only be considered as a last-line agent for PI3Ki-associated hyperglycemia due to its stimulatory effect of PI3K signaling. Clinical studies show that alpelisib-associated hyperglycemia is reversible and manageable, rarely leading to treatment discontinuation. Management of PI3Ki-associated hyperglycemia in patients with breast cancer should focus on the prevention of acute and subacute complications of hyperglycemia, allowing patients to remain on anticancer treatment longer.
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Affiliation(s)
| | - Azeez Farooki
- Memorial Sloan Kettering Cancer Center,
New York, NY, USA
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6
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Gregory JM, Kraft G, Farmer B, Smith MS, LaNeve DC, Williams PE, Tomasek K, Su YR, Wilson CS, Thompson MD, Cherrington AD, Coate KC. Insulin Infusion Is Linked to Increased NPPC Expression in Muscle and Plasma C-type Natriuretic Peptide in Male Dogs. J Endocr Soc 2021; 5:bvab088. [PMID: 34131611 PMCID: PMC8195255 DOI: 10.1210/jendso/bvab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Indexed: 11/19/2022] Open
Abstract
The purpose of this study was to assess insulin-stimulated gene expression in canine skeletal muscle with a particular focus on NPPC, the gene that encodes C-type natriuretic peptide, a key hormonal regulator of cardiometabolic function. Four conscious canines underwent hyperinsulinemic, euglycemic clamp studies. Skeletal muscle biopsy and arterial plasma samples were collected under basal and insulin-stimulated conditions. Bulk RNA sequencing of muscle tissue was performed to identify differentially expressed genes between these 2 steady-state conditions. Our results showed that NPPC was the most highly expressed gene in skeletal muscle in response to insulin infusion, rising 4-fold between basal and insulin-stimulated conditions. In support of our RNA sequencing data, we found that raising the plasma insulin concentration 15-fold above basal elicited a 2-fold (P = 0.0001) increase in arterial plasma concentrations of N-terminal prohormone C-type natriuretic peptide. Our data suggest that insulin may play a role in stimulating secretion of C-type natriuretic peptide by skeletal muscle. In this context, C-type natriuretic peptide may act in a paracrine manner to facilitate muscle–vascular bed crosstalk and potentiate insulin-mediated vasodilation. This could serve to enhance insulin and glucose delivery, particularly in the postprandial absorptive state.
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Affiliation(s)
- Justin M Gregory
- Ian M. Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Marta S Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - David C LaNeve
- Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Phillip E Williams
- Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Kelsey Tomasek
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Yan Ru Su
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Christopher S Wilson
- Ian M. Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | | | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Katie C Coate
- Division of Diabetes, Endocrinology, & Metabolism, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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7
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Lou PH, Lucchinetti E, Wawrzyniak P, Morsy Y, Wawrzyniak M, Scharl M, Krämer SD, Rogler G, Hersberger M, Zaugg M. Choice of Lipid Emulsion Determines Inflammation of the Gut-Liver Axis, Incretin Profile, and Insulin Signaling in a Murine Model of Total Parenteral Nutrition. Mol Nutr Food Res 2021; 65:e2000412. [PMID: 32729969 DOI: 10.1002/mnfr.202000412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/16/2020] [Indexed: 12/19/2022]
Abstract
SCOPE The aim of this study is to test whether the choice of the lipid emulsion in total parenteral nutrition (TPN), that is, n-3 fatty acid-based Omegaven versus n-6 fatty acid-based Intralipid, determines inflammation in the liver, the incretin profile, and insulin resistance. METHODS AND RESULTS Jugular vein catheters (JVC) are placed in C57BL/6 mice and used for TPN for 7 days. Mice are randomized into a saline group (saline infusion with oral chow), an Intralipid group (IL-TPN, no chow), an Omegaven group (OV-TPN, no chow), or a chow only group (without JVC). Both TPN elicite higher abundance of lipopolysaccharide binding protein in the liver, but only IL-TPN increases interleukin-6 and interferon-γ, while OV-TPN reduces interleukin-4, monocyte chemoattractant protein-1, and interleukin-1α. Insulin plasma concentrations are higher in both TPN, while glucagon and glucagon-like peptide-1 (GLP-1) were higher in IL-TPN. Gluconeogenesis is increased in IL-TPN and the nuclear profile of key metabolic transcription factors shows a liver-protective phenotype in OV-TPN. OV-TPN increases insulin sensitivity in the liver and skeletal muscle. CONCLUSION OV-TPN as opposed to IL-TPN mitigates inflammation in the liver and reduces the negative metabolic effects of hyperinsulinemia and hyperglucagonemia by "re-sensitizing" the liver and skeletal muscle to insulin.
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Affiliation(s)
- Phing-How Lou
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Eliana Lucchinetti
- Department of Anesthesiology and Pain Medicine and Cardiovascular Research Centre, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Paulina Wawrzyniak
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Zurich, 8032, Switzerland
| | - Yasser Morsy
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Marcin Wawrzyniak
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Michael Scharl
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Stefanie D Krämer
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, 8093, Switzerland
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Martin Hersberger
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Zurich, 8032, Switzerland
- Center for Integrative Human Physiology, University of Zurich, Zurich, 8057, Switzerland
| | - Michael Zaugg
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
- Department of Anesthesiology and Pain Medicine and Cardiovascular Research Centre, University of Alberta, Edmonton, T6G 2R3, Canada
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Britto FA, Dumas K, Giorgetti-Peraldi S, Ollendorff V, Favier FB. Is REDD1 a metabolic double agent? Lessons from physiology and pathology. Am J Physiol Cell Physiol 2020; 319:C807-C824. [PMID: 32877205 DOI: 10.1152/ajpcell.00340.2020] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Akt/mechanistic target of rapamycin (mTOR) signaling pathway governs macromolecule synthesis, cell growth, and metabolism in response to nutrients and growth factors. Regulated in development and DNA damage response (REDD)1 is a conserved and ubiquitous protein, which is transiently induced in response to multiple stimuli. Acting like an endogenous inhibitor of the Akt/mTOR signaling pathway, REDD1 protein has been shown to regulate cell growth, mitochondrial function, oxidative stress, and apoptosis. Recent studies also indicate that timely REDD1 expression limits Akt/mTOR-dependent synthesis processes to spare energy during metabolic stresses, avoiding energy collapse and detrimental consequences. In contrast to this beneficial role for metabolic adaptation, REDD1 chronic expression appears involved in the pathogenesis of several diseases. Indeed, REDD1 expression is found as an early biomarker in many pathologies including inflammatory diseases, cancer, neurodegenerative disorders, depression, diabetes, and obesity. Moreover, prolonged REDD1 expression is associated with cell apoptosis, excessive reactive oxygen species (ROS) production, and inflammation activation leading to tissue damage. In this review, we decipher several mechanisms that make REDD1 a likely metabolic double agent depending on its duration of expression in different physiological and pathological contexts. We also discuss the role played by REDD1 in the cross talk between the Akt/mTOR signaling pathway and the energetic metabolism.
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Affiliation(s)
| | - Karine Dumas
- Université Cote d'Azur, INSERM, UMR1065, C3M, Nice, France
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Yu Y, Zhang J, Yao S, Pan L, Luo G, Xu N. Apolipoprotein M overexpression through adeno-associated virus gene transfer improves insulin secretion and insulin sensitivity in Goto-Kakizaki rats. J Diabetes Investig 2020; 11:1150-1158. [PMID: 32243104 PMCID: PMC7477524 DOI: 10.1111/jdi.13261] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 03/01/2020] [Accepted: 03/22/2020] [Indexed: 12/11/2022] Open
Abstract
AIMS/OBJECTIVE The development of type 2 diabetes is a result of insulin resistance in various tissues, including skeletal muscle and liver. Apolipoprotein M (ApoM) plays an important role in the function of high-density lipoprotein, and also affects hepatic lipid and glucose metabolism. In this study, we aimed to investigate whether ApoM overexpression modulates glucose metabolism and improves insulin sensitivity. MATERIALS AND METHODS The Goto-Kakizaki (GK) rats were transfected with adeno-associated virus (AAV) encoding rat ApoM gene or control blank. The oral glucose tolerance test (OGTT) and hyperinsulinemic-euglycemic clamp (HEC) experiment were used to assess the insulin sensitivity of GK rats. RESULTS The results show that ApoM messenger ribonucleic acid and protein were significantly overexpressed in the pancreatic tissues. Overexpression of ApoM decreased fasting blood glucose and random blood glucose, improved glucose tolerance, and increased bodyweight and insulin levels in GK rats. The glucose infusion rate of rats in the AAV encoding rat ApoM gene group during HEC test was 1.04-, 1.23- and 1.95-fold higher than that in the AAV control blank group at 1-3 weeks after injection of AAV, respectively. A Wes-ProteinSimple assay and quantification was carried out to assess phosphorylated protein kinase B/protein kinase B protein levels in the muscle tissues of ApoM-overexpressing GK rats, and they were found to be higher than those of the control group at the seventh week after AAV injection. CONCLUSIONS ApoM overexpression through adeno-associated virus gene transfer might improve insulin secretion and insulin sensitivity in GK rats.
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Affiliation(s)
- Yang Yu
- Comprehensive Laboratorythe Third Affiliated Hospital of Soochow UniversityChangzhouChina
| | - Jun Zhang
- Comprehensive Laboratorythe Third Affiliated Hospital of Soochow UniversityChangzhouChina
| | - Shuang Yao
- Comprehensive Laboratorythe Third Affiliated Hospital of Soochow UniversityChangzhouChina
| | - Lili Pan
- Comprehensive Laboratorythe Third Affiliated Hospital of Soochow UniversityChangzhouChina
| | - Guanghua Luo
- Comprehensive Laboratorythe Third Affiliated Hospital of Soochow UniversityChangzhouChina
| | - Ning Xu
- Section of Clinical Chemistry and PharmacologyInstitute of Laboratory MedicineLunds UniversityLundSweden
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10
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Jaiswal N, Gavin MG, Quinn WJ, Luongo TS, Gelfer RG, Baur JA, Titchenell PM. The role of skeletal muscle Akt in the regulation of muscle mass and glucose homeostasis. Mol Metab 2019; 28:1-13. [PMID: 31444134 PMCID: PMC6822261 DOI: 10.1016/j.molmet.2019.08.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE Skeletal muscle insulin signaling is a major determinant of muscle growth and glucose homeostasis. Protein kinase B/Akt plays a prominent role in mediating many of the metabolic effects of insulin. Mice and humans harboring systemic loss-of-function mutations in Akt2, the most abundant Akt isoform in metabolic tissues, are glucose intolerant and insulin resistant. Since the skeletal muscle accounts for a significant amount of postprandial glucose disposal, a popular hypothesis in the diabetes field suggests that a reduction in Akt, specifically in skeletal muscle, leads to systemic glucose intolerance and insulin resistance. Despite this common belief, the specific role of skeletal muscle Akt in muscle growth and insulin sensitivity remains undefined. METHODS We generated multiple mouse models of skeletal muscle Akt deficiency to evaluate the role of muscle Akt signaling in vivo. The effects of these genetic perturbations on muscle mass, glucose homeostasis and insulin sensitivity were assessed using both in vivo and ex vivo assays. RESULTS Surprisingly, mice lacking Akt2 alone in skeletal muscle displayed normal skeletal muscle insulin signaling, glucose tolerance, and insulin sensitivity despite a dramatic reduction in phosphorylated Akt. In contrast, deletion of both Akt isoforms (M-AktDKO) prevented downstream signaling and resulted in muscle atrophy. Despite the absence of Akt signaling, in vivo and ex vivo insulin-stimulated glucose uptake were normal in M-AktDKO mice. Similar effects on insulin sensitivity were observed in mice with prolonged deletion (4 weeks) of both skeletal muscle Akt isoforms selectively in adulthood. Conversely, short term deletion (2 weeks) of skeletal muscle specific Akt in adult muscles impaired insulin tolerance paralleling the effect observed by acute pharmacological inhibition of Akt in vitro. Mechanistically, chronic ablation of Akt induced mitochondrial dysfunction and activation of AMPK, which was required for insulin-stimulated glucose uptake in the absence of Akt. CONCLUSIONS Together, these data indicate that chronic reduction in Akt activity alone in skeletal muscle is not sufficient to induce insulin resistance or prevent glucose uptake in all conditions. Therefore, since insulin-stimulated glucose disposal in skeletal muscle is markedly impaired in insulin-resistant states, we hypothesize that alterations in signaling molecules in addition to skeletal muscle Akt are necessary to perturb glucose tolerance and insulin sensitivity in vivo.
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Affiliation(s)
- N Jaiswal
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - M G Gavin
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - W J Quinn
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - T S Luongo
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - R G Gelfer
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - J A Baur
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA; Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - P M Titchenell
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA; Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
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11
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Sato T, Watanabe Y, Nishimura Y, Inoue M, Morita A, Miura S. Acute fructose intake suppresses fasting-induced hepatic gluconeogenesis through the AKT-FoxO1 pathway. Biochem Biophys Rep 2019; 18:100638. [PMID: 31032430 PMCID: PMC6479072 DOI: 10.1016/j.bbrep.2019.100638] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/19/2019] [Accepted: 04/08/2019] [Indexed: 11/21/2022] Open
Abstract
Excessive intake of fructose increases lipogenesis in the liver, leading to hepatic lipid accumulation and development of fatty liver disease. Metabolic alterations in the liver due to fructose intake have been reported in many studies, but the effect of fructose administration on hepatic gluconeogenesis is not fully understood. The aim of this study was to evaluate the acute effects of fructose administration on fasting-induced hepatic gluconeogenesis. C57BL/6J mice were administered fructose solution after 14 h of fasting and plasma insulin, glucose, free fatty acids, and ketone bodies were analysed. We also measured phosphorylated AKT and forkhead box O (FoxO) 1 protein levels and gene expression related to gluconeogenesis in the liver. Furthermore, we measured glucose production from pyruvate after fructose administration. Glucose-administered mice were used as controls. Fructose administration enhanced phosphorylation of AKT in the liver, without increase of blood insulin levels. Blood free fatty acids and ketone bodies concentrations were as high as those in the fasting group after fructose administration, suggesting that insulin-induced inhibition of lipolysis did not occur in mice administered with fructose. Fructose also enhanced phosphorylation of FoxO1 and suppressed gluconeogenic gene expression, glucose-6-phosphatase activity, and glucose production from pyruvate. The present study suggests that acute fructose administration suppresses fasting-induced hepatic gluconeogenesis in an insulin-independent manner. Fructose administration does not increase blood glucose and insulin levels. Fructose administration suppressed fasting-induced hepatic gluconeogenic gene expression and G6Pase activity. Fructose accelerates FoxO1 phosphorylation through the AKT-FoxO1 pathway. We propose that fructose intake suppresses fasting-induced hepatic gluconeogenesis in an insulin-independent manner.
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Key Words
- AKT
- CREB, cAMP response element binding protein
- ChREBP, carbohydrate response element binding protein
- EDTA, ethylenediaminetetraacetic acid
- FFA, free fatty acid
- FoxO, forkhead box O
- FoxO1
- Fructose
- G6Pase
- G6Pase, glucose-6-phosphatase
- Gluconeogenesis
- Insulin
- PEPCK, phosphoenolpyruvate carboxykinase
- PGC-1α, peroxisome proliferator-activated receptor gamma coactivator-1 alpha
- PI3K, phosphoinositide-3-kinase
- PIP 3, phosphatidylinositol-(3,4,5)-trisphosphate
- SREBP, sterol-regulatory element binding protein
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Affiliation(s)
- Tomoki Sato
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.,Research Fellow of Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan
| | - Yui Watanabe
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Yuri Nishimura
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Mizuki Inoue
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Akihito Morita
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Shinji Miura
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
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12
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Tsuzuki T, Yoshihara T, Ichinoseki-Sekine N, Kakigi R, Takamine Y, Kobayashi H, Naito H. Body temperature elevation during exercise is essential for activating the Akt signaling pathway in the skeletal muscle of type 2 diabetic rats. PLoS One 2018; 13:e0205456. [PMID: 30304029 PMCID: PMC6179285 DOI: 10.1371/journal.pone.0205456] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 09/25/2018] [Indexed: 11/19/2022] Open
Abstract
This study examined the effect of changes in body temperature during exercise on signal transduction-related glucose uptake in the skeletal muscle of type 2 diabetic rats. Otsuka Long-Evans Tokushima Fatty rats (25 weeks of age), which have type 2 diabetes, were divided into the following four weight-matched groups; control (CON, n = 6), exercised under warm temperature (WEx, n = 8), exercised under cold temperature (CEx, n = 8), and heat treatment (HT, n = 6). WEx and CEx animals were subjected to running on a treadmill at 20 m/min for 30 min under warm (25°C) or cold (4°C) temperature. HT animals were exposed to single heat treatment (40–41°C for 30 min) in a heat chamber. Rectal and muscle temperatures were measured immediately after exercise and heat treatment, and the gastrocnemius muscle was sampled under anesthesia. Rectal and muscle temperatures increased significantly in rats in the WEx and HT, but not the CEx, groups. The phosphorylation levels of Akt, AS160, and TBC1D1 (Thr590) were significantly higher in the WEx and HT groups than the CON group (p < 0.05). In contrast, the phosphorylation levels of AMP-activated protein kinase, ACC, and TBC1D1 (Ser660) were significantly higher in rats in the WEx and CEx groups than the CON group (p < 0.05) but did not differ significantly between rats in the WEx and CEx groups. Body temperature elevation by heat treatment did not activate the AMPK signaling. Our data suggest that body temperature elevation during exercise is essential for activating the Akt signaling pathway in the skeletal muscle of rats with type 2 diabetic rats.
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Affiliation(s)
- Takamasa Tsuzuki
- Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
- Faculty of Pharmacy, Meijo University, Aichi, Japan
| | - Toshinori Yoshihara
- Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
| | - Noriko Ichinoseki-Sekine
- Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
- Faculty of Liberal Arts, The Open University of Japan, Chiba, Japan
| | - Ryo Kakigi
- Faculty of Medicine, Juntendo University, Tokyo, Japan
| | - Yuri Takamine
- Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
| | - Hiroyuki Kobayashi
- Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
- Department of General Medicine, Mito Medical Center, Tsukuba University Hospital, Ibaraki, Japan
| | - Hisashi Naito
- Graduate School of Health and Sports Science, Juntendo University, Chiba, Japan
- * E-mail:
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13
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Patel B, Mann GE, Chapple SJ. Concerted redox modulation by sulforaphane alleviates diabetes and cardiometabolic syndrome. Free Radic Biol Med 2018; 122:150-160. [PMID: 29427794 DOI: 10.1016/j.freeradbiomed.2018.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/01/2018] [Accepted: 02/03/2018] [Indexed: 02/07/2023]
Abstract
Diabetes and cardiometabolic disorders such as hypertension and obesity are major risk factors for the development of cardiovascular disease, with a wealth of evidence suggesting that oxidative stress is linked to the initiation and pathogenesis of these disease processes. With yearly increases in the global incidence of cardiovascular diseases (CVD) and diabetes, numerous studies have focused on characterizing whether upregulating antioxidant defenses through exogenous antioxidants (e.g. vitamin E, vitamin C) or activation of endogenous defenses (e.g. the Nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant defense pathway) may be of benefit. The dietary isothiocyanate sulforaphane (SFN) is currently the subject of several clinical trials for a variety of disease states, including the evaluation of its therapeutic potential to ameliorate diabetic and cardiometabolic complications. SFN is a well characterized and potent Nrf2 inducer, however recent studies suggest its protective actions may be in part mediated by its modulation of various pro-inflammatory (e.g. Nuclear factor-kappa B (NFκB)) and metabolic (e.g. Peroxisome Proliferator-Activator Receptor Gamma (PPARγ)) signaling pathways. The focus of this review is to provide a detailed analysis of the known mechanisms by which SFN modulates Nrf2, NFκB and PPARγ signaling and crosstalk and to provide a critical evaluation of the evidence linking these transcriptional pathways with diabetic and cardiometabolic complications and SFN mediated cytoprotection. To allow comparison between rodent and human studies, we discuss the published bioavailability of SFN metabolites achieved in rodents and man in the context of Nrf2, NFκB and PPARγ signaling. Furthermore, we provide an update on the functional outcomes and implicated signaling pathways reported in recent clinical trials with SFN in Type 2 diabetic patients.
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Affiliation(s)
- Bijal Patel
- King's BHF Centre of Research Excellence, School of Cardiovascular Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Giovanni E Mann
- King's BHF Centre of Research Excellence, School of Cardiovascular Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Sarah J Chapple
- King's BHF Centre of Research Excellence, School of Cardiovascular Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom.
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14
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Tokarz VL, MacDonald PE, Klip A. The cell biology of systemic insulin function. J Cell Biol 2018; 217:2273-2289. [PMID: 29622564 PMCID: PMC6028526 DOI: 10.1083/jcb.201802095] [Citation(s) in RCA: 224] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/21/2018] [Accepted: 03/23/2018] [Indexed: 12/12/2022] Open
Abstract
Tokarz et al. review the cell biology of insulin physiology throughout the body, from synthesis to the delivery, action, and final degradation of insulin. Insulin is the paramount anabolic hormone, promoting carbon energy deposition in the body. Its synthesis, quality control, delivery, and action are exquisitely regulated by highly orchestrated intracellular mechanisms in different organs or “stations” of its bodily journey. In this Beyond the Cell review, we focus on these five stages of the journey of insulin through the body and the captivating cell biology that underlies the interaction of insulin with each organ. We first analyze insulin’s biosynthesis in and export from the β-cells of the pancreas. Next, we focus on its first pass and partial clearance in the liver with its temporality and periodicity linked to secretion. Continuing the journey, we briefly describe insulin’s action on the blood vasculature and its still-debated mechanisms of exit from the capillary beds. Once in the parenchymal interstitium of muscle and adipose tissue, insulin promotes glucose uptake into myofibers and adipocytes, and we elaborate on the intricate signaling and vesicle traffic mechanisms that underlie this fundamental function. Finally, we touch upon the renal degradation of insulin to end its action. Cellular discernment of insulin’s availability and action should prove critical to understanding its pivotal physiological functions and how their failure leads to diabetes.
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Affiliation(s)
- Victoria L Tokarz
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Patrick E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada .,Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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15
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Kim JH, Park SJ, Chae U, Seong J, Lee HS, Lee SR, Lee S, Lee DS. Peroxiredoxin 2 mediates insulin sensitivity of skeletal muscles through regulation of protein tyrosine phosphatase oxidation. Int J Biochem Cell Biol 2018; 99:80-90. [PMID: 29605633 DOI: 10.1016/j.biocel.2018.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/07/2018] [Accepted: 03/27/2018] [Indexed: 01/14/2023]
Abstract
Insulin signaling is essential for regulating glucose homeostasis. Numerous studies have demonstrated that reactive oxygen species (ROS) affect insulin signaling, and low ROS levels can act as a signal to regulate cellular function. Peroxiredoxins (Prxs) are highly abundant and widely expressed antioxidant enzymes. However, it is unclear whether antioxidant enzymes, such as Prx2, mediate insulin signaling. The aim of our study was to investigate the influence of Prx2 deficiency on insulin signaling. Our western blot results showed that Prx2 deficiency enhanced insulin signaling and increased oxidation of protein tyrosine phosphatase 1B (PTP1B) and phosphatase and tensin homologue (PTEN) in mouse embryonic fibroblasts (MEFs) treated with insulin. In addition, we assessed ROS levels with a Cytosol-HyPer H2O2 sensor. As a result, increased ROS levels and Akt activation were decreased by N-acetyl-cysteine (Nac), which acted as an antioxidant in Prx2-deficient MEFs. Body weight measurements and glucose tolerance test (GTT) revealed significant body weight reduction and increase in glucose clearance in Prx2-/- mice fed a high-fat diet. Interestingly, glucose transporter type 4 (GLUT4) was significantly higher in Prx2-/- mice than in wild-type mice according to western blotting results. Western blotting also revealed that Akt phosphorylation was higher in Prx2-/- MEFs and muscle tissue than in wild-type. Together, our findings indicate that increased ROS due to Prx2 deficiency promotes insulin sensitivity and glucose clearance in skeletal muscles by increasing protein tyrosine phosphatase (PTPs) oxidation. These results provide novel insights into the fundamental mechanisms of insulin signaling induced by Prx2 deficiency and suggest that ROS-based therapeutic strategies can be used to suppress insulin resistance.
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Affiliation(s)
- Jung-Hak Kim
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea; Division of Endocrinology, Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Sun-Ji Park
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea; Renal Division, School of Medicine, Washington University in St. Louis, MO, 63130, USA
| | - Unbin Chae
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Joongbae Seong
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Hyun-Shik Lee
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Sang-Rae Lee
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Chungcheongbuk-do, 34141, Republic of Korea
| | - Seunghoon Lee
- Animal Biotechnology Division, National Institute of Animal Science, Jeollabuk-do, 55365, Republic of Korea
| | - Dong-Seok Lee
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea.
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16
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Hatting M, Tavares CDJ, Sharabi K, Rines AK, Puigserver P. Insulin regulation of gluconeogenesis. Ann N Y Acad Sci 2017; 1411:21-35. [PMID: 28868790 DOI: 10.1111/nyas.13435] [Citation(s) in RCA: 284] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/16/2017] [Accepted: 06/26/2017] [Indexed: 12/11/2022]
Abstract
The coordinated regulation between cellular glucose uptake and endogenous glucose production is indispensable for the maintenance of constant blood glucose concentrations. The liver contributes significantly to this process by altering the levels of hepatic glucose release, through controlling the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis). Various nutritional and hormonal stimuli signal to alter hepatic gluconeogenic flux, and suppression of this metabolic pathway during the postprandial state can, to a significant extent, be attributed to insulin. Here, we review some of the molecular mechanisms through which insulin modulates hepatic gluconeogenesis, thus controlling glucose production by the liver to ultimately maintain normoglycemia. Various signaling pathways governed by insulin converge at the level of transcriptional regulation of the key hepatic gluconeogenic genes PCK1 and G6PC, highlighting this as one of the focal mechanisms through which gluconeogenesis is modulated. In individuals with compromised insulin signaling, such as insulin resistance in type 2 diabetes, insulin fails to suppress hepatic gluconeogenesis, even in the fed state; hence, an insight into these insulin-moderated pathways is critical for therapeutic purposes.
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Affiliation(s)
- Maximilian Hatting
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Clint D J Tavares
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Kfir Sharabi
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Amy K Rines
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Pere Puigserver
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
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17
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Mechanical stretch activates mammalian target of rapamycin and AMP-activated protein kinase pathways in skeletal muscle cells. Mol Cell Biochem 2015; 406:285-92. [PMID: 25971373 DOI: 10.1007/s11010-015-2446-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 05/07/2015] [Indexed: 10/23/2022]
Abstract
Cellular protein synthesis is believed to be antagonistically regulated by mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) signaling pathways. In the present study, we examined the relationship between mTOR/p70 S6 kinase (p70S6K) and AMPK in response to mechanical stretch. C2C12 myoblasts were grown on a silicone elastomer chamber to confluence and further cultured in differentiation medium for 4 days to form multinucleated myotubes. Cells were subjected to 15% cyclic uniaxial stretch for 4 h at a frequency of 1 Hz. Phosphorylation of p70S6K at threonine 389 and AMPK at threonine 172 of the catalytic α subunit were concomitantly increased by mechanical stretch. Stimulation of the mTOR pathway by adding leucine and insulin increased the phosphorylation of p70S6K without inactivation of AMPK. In contrast, addition of compound C, a pharmacological inhibitor of AMPK, increased the phosphorylation of p70S6K in stretched cells. Activation of AMPK by the addition of 5-amino-4-imidazolecarboxamide ribonucleoside reduced the phosphorylation of p70S6K in response to mechanical stretch. In conclusion, crosstalk between mTOR and AMPK signaling was not tightly regulated in response to physiological stimuli, such as mechanical stress and/or nutrients. However, pharmacological modulation of AMPK influenced the mTOR/p70S6K signaling pathway.
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18
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Cartee GD. Roles of TBC1D1 and TBC1D4 in insulin- and exercise-stimulated glucose transport of skeletal muscle. Diabetologia 2015; 58:19-30. [PMID: 25280670 PMCID: PMC4258142 DOI: 10.1007/s00125-014-3395-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/07/2014] [Indexed: 10/24/2022]
Abstract
This review focuses on two paralogue Rab GTPase activating proteins known as TBC1D1 Tre-2/BUB2/cdc 1 domain family (TBC1D) 1 and TBC1D4 (also called Akt Substrate of 160 kDa, AS160) and their roles in controlling skeletal muscle glucose transport in response to the independent and combined effects of insulin and exercise. Convincing evidence implicates Akt2-dependent TBC1D4 phosphorylation on T642 as a key part of the mechanism for insulin-stimulated glucose uptake by skeletal muscle. TBC1D1 phosphorylation on several insulin-responsive sites (including T596, a site corresponding to T642 in TBC1D4) does not appear to be essential for in vivo insulin-stimulated glucose uptake by skeletal muscle. In vivo exercise or ex vivo contraction of muscle result in greater TBC1D1 phosphorylation on S237 that is likely to be secondary to increased AMP-activated protein kinase activity and potentially important for contraction-stimulated glucose uptake. Several studies that evaluated both normal and insulin-resistant skeletal muscle stimulated with a physiological insulin concentration after a single exercise session found that greater post-exercise insulin-stimulated glucose uptake was accompanied by greater TBC1D4 phosphorylation on several sites. In contrast, enhanced post-exercise insulin sensitivity was not accompanied by greater insulin-stimulated TBC1D1 phosphorylation. The mechanism for greater TBC1D4 phosphorylation in insulin-stimulated muscles after acute exercise is uncertain, and a causal link between enhanced TBC1D4 phosphorylation and increased post-exercise insulin sensitivity has yet to be established. In summary, TBC1D1 and TBC1D4 have important, but distinct roles in regulating muscle glucose transport in response to insulin and exercise.
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Affiliation(s)
- Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, 401 Washtenaw Avenue, Ann Arbor, MI, 48109-2214, USA,
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19
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Abstract
Autophagy is the main cellular catabolic process responsible for degrading organelles and large protein aggregates. It is initiated by the formation of a unique membrane structure, the phagophore, which engulfs part of the cytoplasm and forms a double-membrane vesicle termed the autophagosome. Fusion of the outer autophagosomal membrane with the lysosome and degradation of the inner membrane contents complete the process. The extent of autophagy must be tightly regulated to avoid destruction of proteins and organelles essential for cell survival. Autophagic activity is thus regulated by external and internal cues, which initiate the formation of well-defined autophagy-related protein complexes that mediate autophagosome formation and selective cargo recruitment into these organelles. Autophagosome formation and the signaling pathways that regulate it have recently attracted substantial attention. In this review, we analyze the different signaling pathways that regulate autophagy and discuss recent progress in our understanding of autophagosome biogenesis.
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Affiliation(s)
- Adi Abada
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Zvulun Elazar
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
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20
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21
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Abstract
AMPK is an evolutionary conserved sensor of cellular energy status that is activated during exercise. Pharmacological activation of AMPK promotes glucose uptake, fatty acid oxidation, mitochondrial biogenesis, and insulin sensitivity; processes that are reduced in obesity and contribute to the development of insulin resistance. AMPK deficient mouse models have been used to provide direct genetic evidence either supporting or refuting a role for AMPK in regulating these processes. Exercise promotes glucose uptake by an insulin dependent mechanism involving AMPK. Exercise is important for improving insulin sensitivity; however, it is not known if AMPK is required for these improvements. Understanding how these metabolic processes are regulated is important for the development of new strategies that target obesity-induced insulin resistance. This review will discuss the involvement of AMPK in regulating skeletal muscle metabolism (glucose uptake, glycogen synthesis, and insulin sensitivity).
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Affiliation(s)
- Hayley M. O'Neill
- Protein Chemistry and Metabolism Unit, St. Vincent's Institute of Medical Research, Fitzroy, Australia
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22
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Kunuthur SP, Mocanu MM, Hemmings BA, Hausenloy DJ, Yellon DM. The Akt1 isoform is an essential mediator of ischaemic preconditioning. J Cell Mol Med 2012; 16:1739-49. [PMID: 22117619 PMCID: PMC3822687 DOI: 10.1111/j.1582-4934.2011.01491.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Phosphatidyl-inositol-3-kinase (PI3K)-Akt pathway is essential for conferring cardioprotection in response to ischaemic preconditioning (IPC) stimulus. However, the role of the individual Akt isoforms expressed in the heart in mediating the protective response to IPC is unknown. In this study, we investigated the specific contribution of Akt1 and Akt2 in cardioprotection against ischaemia-reperfusion (I-R) injury. Mice deficient in Akt1 or Akt2 were subjected to in vivo regional myocardial ischaemia for 30 min. followed by reperfusion for 2 hrs with or without a prior IPC stimulus. Our results show that mice deficient in Akt1 were resistant to protection with either one or three cycles of IPC stimulus (42.7 ± 6.5% control versus 38.5 ± 1.9% 1 χ IPC, N = 6, NS; 41.4 ± 6.3% control versus 32.4 ± 3.2% 3 χ IPC, N = 10, NS). Western blot analysis, performed on heart samples taken from Akt1−/− mice subjected to IPC, revealed an impaired phosphorylation of GSK-3β, a downstream effector of Akt, as well as Erk1/2, the parallel component of the reperfusion injury salvage kinase pathway. Akt2−/− mice, which exhibit a diabetic phenotype, however, were amenable to protection with three but not one cycle of IPC (46.4 ± 5.6% control versus 35.9 ± 5.0% in 1 χ IPC, N = 6, NS; 47.0 ± 6.0% control versus 30.8 ± 3.3% in 3 χ IPC, N = 6; *P = 0.039). Akt1 but not Akt2 is essential for mediating a protective response to an IPC stimulus. Impaired activation of GSK-3β and Erk1/2 might be responsible for the lack of protective response to IPC in Akt1−/− mice. The rise in threshold for protection in Akt2−/− mice might be due to their diabetic phenotype.
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Affiliation(s)
- Suma P Kunuthur
- The Hatter Cardiovascular Institute, The Institute of Cardiovascular Science, University College London, London, UK
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A novel PKB/Akt inhibitor, MK-2206, effectively inhibits insulin-stimulated glucose metabolism and protein synthesis in isolated rat skeletal muscle. Biochem J 2012; 447:137-47. [PMID: 22793019 DOI: 10.1042/bj20120772] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PKB (protein kinase B), also known as Akt, is a key component of insulin signalling. Defects in PKB activation lead to insulin resistance and metabolic disorders, whereas PKB overactivation has been linked to tumour growth. Small-molecule PKB inhibitors have thus been developed for cancer treatment, but also represent useful tools to probe the roles of PKB in insulin action. In the present study, we examined the acute effects of two allosteric PKB inhibitors, MK-2206 and Akti 1/2 (Akti) on PKB signalling in incubated rat soleus muscles. We also assessed the effects of the compounds on insulin-stimulated glucose uptake, glycogen and protein synthesis. MK-2206 dose-dependently inhibited insulin-stimulated PKB phosphorylation, PKBβ activity and phosphorylation of PKB downstream targets (including glycogen synthase kinase-3α/β, proline-rich Akt substrate of 40 kDa and Akt substrate of 160 kDa). Insulin-stimulated glucose uptake, glycogen synthesis and glycogen synthase activity were also decreased by MK-2206 in a dose-dependent manner. Incubation with high doses of MK-2206 (10 μM) inhibited insulin-induced p70 ribosomal protein S6 kinase and 4E-BP1 (eukaryotic initiation factor 4E-binding protein-1) phosphorylation associated with increased eEF2 (eukaryotic elongation factor 2) phosphorylation. In contrast, Akti only modestly inhibited insulin-induced PKB and mTOR (mammalian target of rapamycin) signalling, with little or no effect on glucose uptake and protein synthesis. MK-2206, rather than Akti, would thus be the tool of choice for studying the role of PKB in insulin action in skeletal muscle. The results point to a key role for PKB in mediating insulin-stimulated glucose uptake, glycogen synthesis and protein synthesis in skeletal muscle.
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Tripathy S, Jump DB. Elovl5 regulates the mTORC2-Akt-FOXO1 pathway by controlling hepatic cis-vaccenic acid synthesis in diet-induced obese mice. J Lipid Res 2012; 54:71-84. [PMID: 23099444 DOI: 10.1194/jlr.m028787] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Elevated hepatic expression of fatty acid elongase-5 (Elovl5) induces FoxO1 phosphorylation, lowers FoxO1 nuclear content, and suppresses expression of genes involved in gluconeogenesis (GNG). In this report, we define the molecular and metabolic basis of Elovl5 control of FoxO1 phosphorylation. Adenoviral-mediated (Ad-Elovl5) induction of hepatic Elovl5 in diet-induced obese, glucose-intolerant mice and HepG2 cells increased the phosphorylation of Akt2-S(473) [mammalian target of rapamycin complex-2 (mTORC2) site], but not Akt2-T(308) (PDK1 site). The Akt2 inhibitor Akti1/2 blocked Elovl5 induction of FoxO1-S(256) phosphorylation in HepG2 cells. Elevated Elovl5 activity in liver and HepG2 cells induced rictor mRNA, rictor protein, and rictor-mTOR interaction, whereas rictor knockdown (siRNA) attenuated Elovl5 induction of Akt2-S(473) and FoxO1-S(256) phosphorylation in HepG2 cells. FA analysis revealed that the abundance of cis-vaccenic acid (18:1,n-7) was increased in livers of obese mice and HepG2 cells following Ad-Elovl5 infection. Treating HepG2 cells with Elovl5 substrates established that palmitoleic acid (16:1,n-7), but not γ-linolenic acid (18:3,n-6), induced rictor protein, Akt-S(473), and FoxO1-S(256) phosphorylation. Inhibition of FA elongation blocked 16:1,n-7 but not 18:1,n-7 induction of rictor protein and Akt-S(473) and FoxO1-S(256) phosphorylation. These results establish a novel link between Elovl5-mediated synthesis of 18:1,n-7 and GNG through the control of the mTORC2-Akt-FoxO1 pathway.
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Affiliation(s)
- Sasmita Tripathy
- Nutrition Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
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25
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Teixeira SS, Tamrakar AK, Goulart-Silva F, Serrano-Nascimento C, Klip A, Nunes MT. Triiodothyronine acutely stimulates glucose transport into L6 muscle cells without increasing surface GLUT4, GLUT1, or GLUT3. Thyroid 2012; 22:747-54. [PMID: 22663547 PMCID: PMC3387762 DOI: 10.1089/thy.2011.0422] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Thyroid hormones (THs) act genomically to stimulate glucose transport by elevating glucose transporter (Slc2a) expression and glucose utilization by cells. However, nongenomic effects of THs are now emerging. Here, we assess how triiodothyronine (T(3)) acutely affects glucose transport and the content of GLUT4, GLUT1, and GLUT3 at the surface of muscle cells, and possible interactions between T(3) and insulin action. METHODS Differentiated L6 myotubes transfected with myc-tagged Slc2a4 (L6-GLUT4myc) or Slc2a1 (L6-GLUT1myc) and wild-type L6 myotubes were studied in the following conditions: control, hypothyroid (Tx), Tx plus T(3), Tx plus insulin, and Tx plus insulin and T(3). RESULTS Glucose uptake and GLUT4 content at the cell surface decreased in the Tx group relative to controls. T(3) treatment for 30 minutes increased glucose transport into L6-GLUT4myc cells without altering surface GLUT4 content, which increased only thereafter. The total amount of GLUT4 protein remained unchanged among the groups studied. The surface GLUT1 content of L6-GLUT1myc cells also remained unaltered after T(3) treatment; however, in these cells glucose transport was not stimulated by T(3). In wild-type L6 cells, although T(3) treatment increased the total amount of GLUT3, it did not change the surface GLUT3 content. Moreover, within 30 minutes, T(3) stimulation of glucose uptake was additive to that of insulin in L6-GLUT4myc cells. As expected, insulin elevated surface GLUT4 content and glucose uptake. However, interestingly, surface GLUT4 content remained unchanged or even dropped with T(3) plus insulin. CONCLUSIONS These data reveal that T(3) rapidly increases glucose uptake in L6-GLUT4myc cells, which, at least for 30 minutes, did not depend on an increment in GLUT4 at the cell surface yet potentiates insulin action. We propose that this rapid T(3) effect involves activation of GLUT4 transporters at the cell surface, but cannot discount the involvement of an unknown GLUT.
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Affiliation(s)
- Silvania Silva Teixeira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Francemilson Goulart-Silva
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Caroline Serrano-Nascimento
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Amira Klip
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Maria Tereza Nunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Bikman BT, Guan Y, Shui G, Siddique MM, Holland WL, Kim JY, Fabriàs G, Wenk MR, Summers SA. Fenretinide prevents lipid-induced insulin resistance by blocking ceramide biosynthesis. J Biol Chem 2012; 287:17426-17437. [PMID: 22474281 PMCID: PMC3366851 DOI: 10.1074/jbc.m112.359950] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 03/30/2012] [Indexed: 01/01/2023] Open
Abstract
Fenretinide is a synthetic retinoid that is being tested in clinical trials for the treatment of breast cancer and insulin resistance, but its mechanism of action has been elusive. Recent in vitro data indicate that fenretinide inhibits dihydroceramide desaturase, an enzyme involved in the biosynthesis of lipotoxic ceramides that antagonize insulin action. Because of this finding, we assessed whether fenretinide could improve insulin sensitivity and glucose homeostasis in vitro and in vivo by controlling ceramide production. The effect of fenretinide on insulin action and the cellular lipidome was assessed in a number of lipid-challenged models including cultured myotubes and isolated muscles strips incubated with exogenous fatty acids and mice fed a high-fat diet. Insulin action was evaluated in the various models by measuring glucose uptake or disposal and the activation of Akt/PKB, a serine/threonine kinase that is obligate for insulin-stimulated anabolism. The effects of fenretinide on cellular lipid levels were assessed by LC-MS/MS. Fenretinide negated lipid-induced insulin resistance in each of the model systems assayed. Simultaneously, the drug depleted cells of ceramide, while promoting the accumulation of the precursor dihydroceramide, a substrate for the reaction catalyzed by Des1. These data suggest that fenretinide improves insulin sensitivity, at least in part, by inhibiting Des1 and suggest that therapeutics targeting this enzyme may be a viable therapeutic means for normalizing glucose homeostasis in the overweight and diabetic.
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Affiliation(s)
- Benjamin T Bikman
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah 84602; Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore 169857.
| | - Yuguang Guan
- Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore 169857
| | - Guanghou Shui
- Department of Biochemistry and, National University of Singapore, Singapore 119077; Life Sciences Institute, National University of Singapore, Singapore 119077
| | - M Mobin Siddique
- Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore 169857
| | - William L Holland
- Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas, Texas 75390
| | - Ji Yun Kim
- National University of Singapore High School of Mathematics and Science, Singapore 129957
| | - Gemma Fabriàs
- Research Unit on BioActive Molecules (RUBAM), Departament de Química Orgànica Biològica, Institut d'Investigacions Químiques i Ambientals de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), 08034 Barcelona, Spain
| | - Markus R Wenk
- Department of Biochemistry and, National University of Singapore, Singapore 119077; Life Sciences Institute, National University of Singapore, Singapore 119077; Department of Biological Sciences, National University of Singapore, Singapore 169857
| | - Scott A Summers
- Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore 169857; Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina 27710
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Jamart C, Francaux M, Millet GY, Deldicque L, Frère D, Féasson L. Modulation of autophagy and ubiquitin-proteasome pathways during ultra-endurance running. J Appl Physiol (1985) 2012; 112:1529-37. [PMID: 22345427 DOI: 10.1152/japplphysiol.00952.2011] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In this study, the coordinated activation of ubiquitin-proteasome pathway (UPP), autophagy-lysosomal pathway (ALP), and mitochondrial remodeling including mitophagy was assessed by measuring protein markers during ultra-endurance running exercise in human skeletal muscle. Eleven male, experienced ultra-endurance athletes ran for 24 h on a treadmill. Muscle biopsy samples were taken from the vastus lateralis muscle 2 h before starting and immediately after finishing exercise. Athletes ran 149.8 ± 16.3 km with an effective running time of 18 h 42 min ( ± 41 min). The phosphorylation state of Akt (-74 ± 5%; P < 0.001), FOXO3a (-49 ± 9%; P < 0.001), mTOR Ser2448 (-32 ± 14%; P = 0.028), and 4E-BP1 (-34 ± 7%; P < 0.001) was decreased, whereas AMPK phosphorylation state increased by 247 ± 170% (P = 0.042). Proteasome β2 subunit activity increased by 95 ± 44% (P = 0.028), whereas the activities associated with the β1 and β5 subunits remained unchanged. MuRF1 protein level increased by 55 ± 26% (P = 0.034), whereas MAFbx protein and ubiquitin-conjugated protein levels did not change. LC3bII increased by 554 ± 256% (P = 0.005), and the form of ATG12 conjugated to ATG5 increased by 36 ± 17% (P = 0.042). The mitochondrial fission marker phospho-DRP1 increased by 110 ± 47% (P = 0.003), whereas the fusion marker Mfn1 and the mitophagy markers Parkin and PINK1 remained unchanged. These results fit well with a coordinated regulation of ALP and UPP triggered by FOXO3 and AMPK during ultra-endurance exercise.
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Affiliation(s)
- Cécile Jamart
- Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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28
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Potentiation of neuronal insulin signaling and glucose uptake by resveratrol: the involvement of AMPK. Pharmacol Rep 2011; 63:1162-8. [DOI: 10.1016/s1734-1140(11)70635-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 05/11/2011] [Indexed: 11/21/2022]
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Gray SR, Kamolrat T. The effect of exercise induced cytokines on insulin stimulated glucose transport in C2C12 cells. Cytokine 2011; 55:221-8. [DOI: 10.1016/j.cyto.2011.04.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 04/21/2011] [Accepted: 04/26/2011] [Indexed: 01/18/2023]
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Kim HJ, Jamart C, Deldicque L, An GL, Lee YH, Kim CK, Raymackers JM, Francaux M. Endoplasmic reticulum stress markers and ubiquitin–proteasome pathway activity in response to a 200-km run. Med Sci Sports Exerc 2011; 43:18-25. [PMID: 20473228 DOI: 10.1249/mss.0b013e3181e4c5d1] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE This study investigated whether a 200-km run modulates signaling pathways implicated in cellular stress in skeletal muscle, with special attention paid to the endoplasmic reticulum (ER) stress and to the activation of the ubiquitin-proteasome pathway. METHODS Eight men ran 200 km (28 h 03 min ± 2 h 01 min). Two muscle biopsies were obtained from the vastus lateralis muscle 2 wk before and 3 h after the race. Mitogen-activated protein kinase, ubiquitin-proteasome pathway, ER stress, inflammation, and oxidative stress markers were assayed by Western blot analysis or by quantitative real-time polymerase chain reaction. Chymotrypsin-like activity of the proteasome was measured by a fluorimetric assay. RESULTS Phosphorylation states of extracellular signal-related kinase 1/2 (+401% ± 173.8%, P = 0.027) and c-Jun N-terminal (+149% ± 61.9%, P = 0.023) increased after the race, whereas p38 phosphorylation remained unchanged. Increases in BiP (+235% ± 94.7%, P = 0.021) and in the messenger RNA level of total (+138% ± 31.2%, P = 0.002) and spliced X-box binding protein 1 (+241% ± 53.3%, P = 0.001) indicated the presence of ER stress. Transcripts of inflammatory markers interleukin-6 (+403% ± 96.1%, P = 0.002) and tumor necrosis factor-α (+233% ± 58.4%, P = 0.003) as well as oxidative stress markers metallothionein 1F (+519% ± 258.3%, P = 0.042), metallothionein 1H (+666% ± 157.5%, P = 0.002), and nicotinamide adenine dinucleotide phosphate-oxidase (NADPH oxidase) (+162% ± 60.5%, P = 0.016) were increased. The messenger RNA level of the ubiquitin ligases muscle-specific RING finger 1 (+583% ± 244.3%, P = 0.024) and muscle atrophy F-box (+249% ± 83.8%, P = 0.011) and the C2 proteasome subunit (+116% ± 40.6%, P = 0.012) also increased. Surprisingly, the amount of ubiquitin-conjugated proteins and the chymotrypsin-like activity of the proteasome were decreased by 20% ± 8.3% (P = 0.025) and 21% ± 4.4% (P = 0.001), respectively. The expression of ubiquitin-specific protease 28 deubiquitinase was increased (+81% ± 37.9%, P = 0.034). CONCLUSIONS In the skeletal muscle, a 200-km run activates the expression of ubiquitin ligases muscle-specific RING finger 1 and muscle atrophy F-box as well as various cellular stresses, among which are ER stress, oxidative stress, and inflammation. Meanwhile, compensatory mechanisms seem also triggered: the unfolded protein response is up-regulated, and the chymotrypsin-like activity of the proteasome is repressed.
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Affiliation(s)
- Hyo Jeong Kim
- Human Physiology, Korea National Sport University, Seoul, South Korea
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Lau P, Fitzsimmons RL, Pearen MA, Watt MJ, Muscat GEO. Homozygous staggerer (sg/sg) mice display improved insulin sensitivity and enhanced glucose uptake in skeletal muscle. Diabetologia 2011; 54:1169-80. [PMID: 21279323 PMCID: PMC3071927 DOI: 10.1007/s00125-011-2046-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 12/03/2010] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Homozygous staggerer (sg/sg) mice, which have decreased and dysfunctional Rorα (also known as Rora) expression in all tissues, display a lean and dyslipidaemic phenotype. They are also resistant to (high fat) diet-induced obesity. We explored whether retinoic acid receptor-related orphan receptor (ROR) α action in skeletal muscle was involved in the regulation of glucose metabolism. METHODS We used a three-armed genomic approach, including expression profiling, ingenuity analysis and quantitative PCR validation to identify the signalling pathway(s) in skeletal muscle that are perturbed in sg/sg mice. Moreover, western analysis, functional insulin and glucose tolerance tests, and ex vivo glucose uptake assays were used to phenotypically characterise the impact of aberrant v-AKT murine thymoma viral oncogene homologue (AKT) signalling. RESULTS Homozygous and heterozygous (sg/sg and sg/+) animals exhibited decreased fasting blood glucose levels, mildly improved glucose tolerance and increased insulin sensitivity. Illumina expression profiling and bioinformatic analysis indicated the involvement of RORα in metabolic disease and phosphatidylinositol 3-kinase-AKT signalling. Quantitative PCR and western analysis validated increased AKT2 (mRNA and protein) and phosphorylation in sg/sg mice in the basal state. This was associated with increased expression of Tbc1d1 and Glut4 (also known as Slc2a4) mRNA and protein. Finally, in agreement with the phenotype, we observed increased (absolute) levels of AKT and phosphorylated AKT (in the basal and insulin stimulated states), and of (ex vivo) glucose uptake in skeletal muscle from sg/sg mice relative to wild-type littermates. CONCLUSIONS/INTERPRETATION We propose that Rorα plays an important role in regulation of the AKT2 signalling cascade, which controls glucose uptake in skeletal muscle.
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Affiliation(s)
- P. Lau
- Obesity Research Centre, Institute for Molecular Bioscience, The University of Queensland, Services Rd, St Lucia, Queensland, 4072 Australia
| | - R. L. Fitzsimmons
- Obesity Research Centre, Institute for Molecular Bioscience, The University of Queensland, Services Rd, St Lucia, Queensland, 4072 Australia
| | - M. A. Pearen
- Obesity Research Centre, Institute for Molecular Bioscience, The University of Queensland, Services Rd, St Lucia, Queensland, 4072 Australia
| | - M. J. Watt
- Department of Physiology, Monash University, Clayton, VIC Australia
| | - G. E. O. Muscat
- Obesity Research Centre, Institute for Molecular Bioscience, The University of Queensland, Services Rd, St Lucia, Queensland, 4072 Australia
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Holland WL, Bikman BT, Wang LP, Yuguang G, Sargent KM, Bulchand S, Knotts TA, Shui G, Clegg DJ, Wenk MR, Pagliassotti MJ, Scherer PE, Summers SA. Lipid-induced insulin resistance mediated by the proinflammatory receptor TLR4 requires saturated fatty acid-induced ceramide biosynthesis in mice. J Clin Invest 2011; 121:1858-70. [PMID: 21490391 PMCID: PMC3083776 DOI: 10.1172/jci43378] [Citation(s) in RCA: 500] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 02/02/2011] [Indexed: 02/06/2023] Open
Abstract
Obesity is associated with an enhanced inflammatory response that exacerbates insulin resistance and contributes to diabetes, atherosclerosis, and cardiovascular disease. One mechanism accounting for the increased inflammation associated with obesity is activation of the innate immune signaling pathway triggered by TLR4 recognition of saturated fatty acids, an event that is essential for lipid-induced insulin resistance. Using in vitro and in vivo systems to model lipid induction of TLR4-dependent inflammatory events in rodents, we show here that TLR4 is an upstream signaling component required for saturated fatty acid-induced ceramide biosynthesis. This increase in ceramide production was associated with the upregulation of genes driving ceramide biosynthesis, an event dependent of the activity of the proinflammatory kinase IKKβ. Importantly, increased ceramide production was not required for TLR4-dependent induction of inflammatory cytokines, but it was essential for TLR4-dependent insulin resistance. These findings suggest that sphingolipids such as ceramide might be key components of the signaling networks that link lipid-induced inflammatory pathways to the antagonism of insulin action that contributes to diabetes.
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Affiliation(s)
- William L. Holland
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Benjamin T. Bikman
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Li-Ping Wang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Guan Yuguang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Katherine M. Sargent
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Sarada Bulchand
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Trina A. Knotts
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Guanghou Shui
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Deborah J. Clegg
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Markus R. Wenk
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Michael J. Pagliassotti
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Philipp E. Scherer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
| | - Scott A. Summers
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Program in Cardiovascular and Metabolic Diseases, Duke-National University of Singapore Graduate Medical School, Singapore.
Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina, USA.
Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
United States Department of Agriculture, Agricultural Research Service Western Human Nutrition Research Center, Davis, California, USA.
Department of Biochemistry, National University of Singapore, Singapore.
Department of Nutrition, Colorado State University, Fort Collins, Colorado, USA
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Raichur S, Fitzsimmons RL, Myers SA, Pearen MA, Lau P, Eriksson N, Wang SM, Muscat GEO. Identification and validation of the pathways and functions regulated by the orphan nuclear receptor, ROR alpha1, in skeletal muscle. Nucleic Acids Res 2010; 38:4296-312. [PMID: 20338882 PMCID: PMC2910057 DOI: 10.1093/nar/gkq180] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The retinoic acid receptor-related orphan receptor (ROR) alpha has been demonstrated to regulate lipid metabolism. We were interested in the RORα1 dependent physiological functions in skeletal muscle. This major mass organ accounts for ∼40% of the total body mass and significant levels of lipid catabolism, glucose disposal and energy expenditure. We utilized the strategy of targeted muscle-specific expression of a truncated (dominant negative) RORα1ΔDE in transgenic mice to investigate RORα1 signaling in this tissue. Expression profiling and pathway analysis indicated that RORα influenced genes involved in: (i) lipid and carbohydrate metabolism, cardiovascular and metabolic disease; (ii) LXR nuclear receptor signaling and (iii) Akt and AMPK signaling. This analysis was validated by quantitative PCR analysis using TaqMan low-density arrays, coupled to statistical analysis (with Empirical Bayes and Benjamini–Hochberg). Moreover, westerns and metabolic profiling were utilized to validate the genes, proteins and pathways (lipogenic, Akt, AMPK and fatty acid oxidation) involved in the regulation of metabolism by RORα1. The identified genes and pathways were in concordance with the demonstration of hyperglycemia, glucose intolerance, attenuated insulin-stimulated phosphorylation of Akt and impaired glucose uptake in the transgenic heterozygous Tg-RORα1ΔDE animals. In conclusion, we propose that RORα1 is involved in regulating the Akt2-AMPK signaling pathways in the context of lipid homeostasis in skeletal muscle.
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Affiliation(s)
- S Raichur
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland, 4072, Australia
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Granlund A, Kotova O, Benziane B, Galuska D, Jensen-Waern M, Chibalin AV, Essén-Gustavsson B. Effects of exercise on muscle glycogen synthesis signalling and enzyme activities in pigs carrying the PRKAG3 mutation. Exp Physiol 2009; 95:541-9. [PMID: 20028849 DOI: 10.1113/expphysiol.2009.051326] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The dominant RN mutation in pigs results in excessive glycogen storage in skeletal muscle. The mutation is situated in the PRKAG3 gene, which encodes a muscle-specific isoform of the AMP-activated protein kinase (AMPK) gamma3 subunit. AMPK is an important regulator of carbohydrate and fat metabolism in mammalian cells. The aim of the present study was to examine the effect of exercise on glycogen synthesis signalling pathways in muscle and to study enzyme activities of importance in carbohydrate metabolism in pigs with or without the PRKAG3 mutation. Glycogen content, metabolic enzyme activities and expression or phosphorylation of signalling proteins were analysed in skeletal muscle specimens obtained at rest, after a single treadmill exercise bout and after 3 h recovery. The PRKAG3 mutation carriers had higher glycogen content, a tendency for lower expression of AMPK (P < 0.07) and higher hexokinase and phosphorylase activities, whereas citrate synthase, 3-hydroxyacyl-CoA dehydrogenase and glycogen synthase activities did not differ between genotypes. Carriers and non-carriers of the RN mutation showed a similar degradation of glycogen after exercise, whereas the rate of resynthesis was faster in the carriers. Acute exercise stimulated Akt phosphorylation on Ser(473) in both genotypes, and the effect was greater in the carriers than in the non-carriers. Acute exercise also stimulated phosphorylation of Akt substrate of 160 kDA and Glycogen synthase kinase 3 in the carriers and GSK3alpha in the non-carriers. In conclusion, the increased rate of glycogen synthesis following exercise in pigs carrying the PRKAG3 mutation correlates with an increased signalling response of Akt and its substrate, AS160, and a higher activity of hexokinase, indicating an increased glucose influx and phosphorylation of glucose, directed towards glycogen synthesis.
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Affiliation(s)
- Anna Granlund
- Department of Clinical Sciences, Section for Comparative Physiology and Medicine, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
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Iwanaka N, Egawa T, Satoubu N, Karaike K, Ma X, Masuda S, Hayashi T. Leucine modulates contraction- and insulin-stimulated glucose transport and upstream signaling events in rat skeletal muscle. J Appl Physiol (1985) 2009; 108:274-82. [PMID: 19940100 DOI: 10.1152/japplphysiol.00420.2009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Leucine has profound effects on glucose metabolism in muscle; however, the effects of leucine on glucose transport in muscle have not been well documented. We investigated the effects of leucine on contraction- and insulin-stimulated glucose transport in isolated rat epitrochlearis muscle in vitro. In the absence of insulin, tetanic contraction increased 3-O-methyl-D-glucose (3-MG) transport and Thr(172) phosphorylation of the catalytic alpha-subunit of 5'-AMP-activated protein kinase (AMPK), a signaling intermediary leading to insulin-independent glucose transport. Leucine (2 mM, 30 min) significantly enhanced contraction-stimulated 3-MG transport and AMPK phosphorylation, accompanied by increased phosphorylation of p70 S6 kinase (p70S6K) Thr(389). The stimulatory effects of leucine on 3-MG transport and AMPK phosphorylation were canceled by STO-609 blockade of Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK) or rapamycin blockade of p70S6K. On the other hand, leucine blunted insulin-stimulated 3-MG transport and reduced insulin-stimulated Akt Thr(473) phosphorylation. Leucine increased insulin-stimulated p70S6K Thr(389) phosphorylation and enhanced the inhibitory phosphorylation of the insulin receptor substrate 1 (IRS1) Ser(636/639). Furthermore, the effects of leucine on insulin-stimulated 3-MG transport and IRS phosphorylation were abolished by rapamycin. These results indicate that leucine activates contraction-stimulated glucose transport and inhibits insulin-stimulated glucose transport in skeletal muscle by activating mammalian target of rapamycin (mTOR)/p70S6K signaling. Enhanced increases in contraction-stimulated AMPK Thr(172) phosphorylation and insulin-stimulated IRS1 Ser(636/639) phosphorylation might be responsible for these opposing effects of leucine, respectively.
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Affiliation(s)
- Nobumasa Iwanaka
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto Univ., Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan
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36
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Lai YC, Lin FC, Jensen J. Glycogen content regulates insulin- but not contraction-mediated glycogen synthase activation in the rat slow-twitch soleus muscles. Acta Physiol (Oxf) 2009; 197:139-50. [PMID: 19432592 DOI: 10.1111/j.1748-1716.2009.01998.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The aim of this study was to investigate the effect of glycogen content on glycogen synthase (GS) activation and phosphorylation in the slow-twitch soleus muscles after contraction, during insulin stimulation and when these two stimuli were combined. METHODS Glycogen content was manipulated in vivo with 24 h fasting and fasting followed by 24 h refeeding. Soleus strips were electrically stimulated for 30 min in vitro, and GS activation and phosphorylation were investigated after an additional 30 min incubation with or without insulin. RESULTS Fasting reduced glycogen content in soleus muscle by 40% and refeeding enhanced by 40%, compared to rats with free access to chow. Insulin-stimulated GS fractional activity was inversely correlated with glycogen content (R = -0.95, P < 0.001, n = 24) and rate of glycogen synthesis was also inversely correlated with glycogen content (R = -0.70, P < 0.001, n = 36). After contraction, GS fractional activity was increased to similar levels in muscles with low, normal and high glycogen content; rate of glycogen synthesis after contraction was also similar. After contraction, insulin additively increased GS activation at all glycogen contents. Group means of GS fractional activity was inversely correlated with GS Ser(641) (R = -0.93, P < 0.001) and Ser(645,649,653,657) (R = -0.85, P < 0.001) phosphorylation, but not with Ser(7) phosphorylation. CONCLUSION Glycogen content regulates insulin- but not contraction-stimulated GS activation and glycogen synthesis in soleus muscles. Furthermore, phosphorylation of GS Ser(641) and Ser(645,649,653,657) seems to regulate GS activity in soleus.
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Affiliation(s)
- Y-C Lai
- Department of Physiology, National Institute of Occupational Health, Oslo, Norway
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37
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Richmond SR, Touchberry CD, Gallagher PM. Forskolin attenuates the action of insulin on the Akt–mTOR pathway in human skeletal muscle. Appl Physiol Nutr Metab 2009; 34:916-25. [DOI: 10.1139/h09-096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Forskolin (FSK) is capable of both stimulating and inhibiting the intracellular signaling pathways of protein synthesis tissues other than skeletal muscle. The purpose of this investigation was to determine if FSK administration affects various elements of the protein kinase B (Akt)–mammalian target of rapamycin (mTOR) pathway in human skeletal muscle. Ten (n = 10) healthy, young (21.6 ± 1.3 years), nonobese (body mass index = 25.5 ± 3.5 kg·m–2), recreationally active males were selected for participation. Following an 8 h fast, 2 muscle biopsies of the vastus lateralis were performed. The samples were sectioned and exposed to 4 in vitro treatment conditions: basal, FSK, insulin (INS), and FSK+INS. The samples were then analyzed for total and phosphorylated levels of Akt, mTOR, S6 kinase (S6K1), and 4E binding protein (4EBP1). Akt phosphorylation was significantly greater in the INS-treated samples compared with the basal and FSK conditions (p = 0.007). Furthermore, the ratio of phosphorylated Akt to total Akt (P/T) was higher in the INS samples compared with the basal and FSK samples (p = 0.001). There were no differences in mTOR phosphorylation among the 4 groups; however, total mTOR was significantly greater in the FSK+INS group (p = 0.006). There were also no differences in phosphorylated or total levels of S6K1 among the 4 groups. However, 4EBP1 phosphorylation was significantly greater in the INS-treated samples compared with the basal (p = 0.003) and FSK (p = 0.004) treatments. There were no differences in the ratio of phosphorylated 4EBP1 to total 4EBP1 (P/T) among the 4 groups. These results indicate that FSK does not activate the Akt–mTOR pathway in human skeletal muscle; however, these results suggest that FSK may inhibit the actions of INS on this pathway.
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Affiliation(s)
- Scott R. Richmond
- Applied Physiology Laboratory, University of Kansas, Lawrence, KS 66045, USA
| | - Chad D. Touchberry
- Applied Physiology Laboratory, University of Kansas, Lawrence, KS 66045, USA
| | - Philip M. Gallagher
- Applied Physiology Laboratory, University of Kansas, Lawrence, KS 66045, USA
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38
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Gray SR, Ratkevicius A, Wackerhage H, Coats P, Nimmo MA. The effect of interleukin-6 and the interleukin-6 receptor on glucose transport in mouse skeletal muscle. Exp Physiol 2009; 94:899-905. [PMID: 19482899 DOI: 10.1113/expphysiol.2009.048173] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Exercise results in an increase in interleukin-6 (IL-6), its receptor (IL-6R) and skeletal muscle glucose transport. Interleukin-6 has been found to have equivocal effects on glucose transport, with no studies, to our knowledge, investigating any potential role of IL-6R. In the present study, we hypothesized that a combined preparation of IL-6 and soluble IL-6R (sIL-6R) would stimulate glucose transport. Mouse soleus muscles were incubated with physiological and supraphysiological concentrations of IL-6 and a combination of IL-6 and sIL-6R. Total and phosphorylated AMP-activated protein kinase (AMPK) and Protein Kinase B (PKB/Akt) were also measured by Western blotting. Exposure to both physiological (80 pg ml(-1)) and supraphysiological IL-6 (120 ng ml(-1)) had no effect on glucose transport. At physiological levels, exposure to a combination of IL-6 and sIL-6R (32 ng ml(-1)) resulted in a 1.4-fold increase (P < 0.05) in basal glucose transport with no change to the phosphorylation of AMPK. Exposure to supraphysiological levels of IL-6 and sIL-6R (120 ng ml(-1)) resulted in an approximately twofold increase (P < 0.05) in basal glucose transport and an increase (P < 0.05) in AMPK phosphorylation. No effect of IL-6 or sIL-6R was observed on insulin-stimulated glucose transport. These findings demonstrate that, while IL-6 alone does not stimulate glucose transport in mouse soleus muscle, when sIL-6R is introduced glucose transport is directly stimulated, partly through AMPK-dependent signalling.
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Affiliation(s)
- Stuart R Gray
- Department of Sport & Exercise Sciences, Loughborough University, Ashby Road, Loughborough, Leicestershire LE113TU, UK
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39
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Jung KH, Choi HS, Kim DH, Han MY, Chang UJ, Yim SV, Song BC, Kim CH, Kang SA. Epigallocatechin Gallate Stimulates Glucose Uptake Through the Phosphatidylinositol 3-Kinase-Mediated Pathway in L6 Rat Skeletal Muscle Cells. J Med Food 2008; 11:429-34. [DOI: 10.1089/jmf.2007.0107] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Kyung Hee Jung
- Department of Clinical Pharmacology, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
- Department of Kowang Medical Research Institute, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Han Sung Choi
- Department of Emergency Medicine, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Dong Hwan Kim
- Department of Kowang Medical Research Institute, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Mi Young Han
- Department of Kowang Medical Research Institute, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Un Jae Chang
- Department of Food and Nutrition, Dongduk Women's University, Seoul, Republic of Korea
| | - Sung-Vin Yim
- Department of Clinical Pharmacology, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
- Department of Kowang Medical Research Institute, College of Medicine, Kyung Hee University, Seoul, Republic of Korea
| | - Byeng Chun Song
- Department of Human Environmental Sciences, Konkuk University, Chungbuk, Seoul, Republic of Korea
| | - Chul-Ho Kim
- Biotechnology Research Division, Jeonbuk Branch Institute Molecular Bioprocess Research Center, Korea Research Institute of Bioscience and Biotechnology, Taejon, Seoul, Republic of Korea
| | - Soon Ah Kang
- Department of Fermented Food Science, Seoul University of Venture & Information, Seoul, Republic of Korea
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40
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Deldicque L, Atherton P, Patel R, Theisen D, Nielens H, Rennie MJ, Francaux M. Decrease in Akt/PKB signalling in human skeletal muscle by resistance exercise. Eur J Appl Physiol 2008; 104:57-65. [PMID: 18535836 DOI: 10.1007/s00421-008-0786-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2008] [Indexed: 02/07/2023]
Abstract
We analysed the effects of resistance exercise upon the phosphorylation state of proteins associated with adaptive processes from the Akt/PKB (protein kinase B) and the mitogen-activated protein kinase (MAPK) pathways. Nine healthy young men (21.7 +/- 0.55 year) performed 10 sets of 10 leg extensions at 80% of their 1-RM (repetition maximum). Muscle biopsies were taken from the vastus lateralis at rest, within the first 30 s after exercise and at 24 h post-exercise. Immediately post exercise, the phosphorylation states of Akt/PKB on Thr308 and Ser473 and 4E-BP1 on Thr37/46 (eukaryotic initiation factor 4E-binding protein 1) were decreased (-60 to -90%, P < 0.05). Conversely, the phosphorylation of p70(s6k) (p70 ribosomal S6 kinase) on Thr421/Ser424 was increased more than 20-fold (P < 0.05), and this was associated with a 10- to 50-fold increase in the phosphorylation of p38 and ERK1/2 (extracellular signal-regulated kinase) (P < 0.05). Twenty-four hours post-exercise the phosphorylation state of Akt/PKB on Thr308 was depressed, whereas the phosphorylation of p70(s6k) on Thr421/Ser424 and sarcoplasmic ERK1/2 were elevated. The present results indicate that high-intensity resistance exercise in the fasted state inhibits Akt/PKB and 4E-BP1 whilst concomitantly augmenting MAPK signalling and p70(s6k) on Thr421/Ser424.
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Affiliation(s)
- Louise Deldicque
- Department of Physical Education and Rehabilitation, Université catholique de Louvain, Place Pierre de Coubertin 1, Louvain-la-Neuve, Belgium
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41
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Abstract
The development of alcoholic muscle disease, which affects both cardiac and skeletal muscle, leads to increased morbidity and mortality in patients who abuse alcohol. The disease pathology includes myocyte degeneration, loss of striations, and myofilament dissolution, which is consistent with alterations in structural and myofibrillar proteins. One explanation for the changes in myofibrillar architecture is that the expression of cellular proteins may be compromised by ethanol consumption. The dynamic balance of proteins in striated muscle is dependent upon rates of protein synthesis and protein degradation. We have shown that protein synthesis is depressed in striated muscle after either acute alcohol intoxication or chronic alcohol ingestion. The loss of myofibrillar proteins occurs prior to any detection of abnormal muscle function in vivo. It is therefore of major importance to evaluate the regulation of protein turnover after ethanol consumption. This review describes protocols to study protein synthesis either in vivo or under in vitro conditions. The methods can be modified for studies involving transgenic mice allowing mechanisms responsible for the defects in protein synthesis to be dissected.
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42
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Wright D, Sutherland L. Antioxidant supplemention in the treatment of skeletal muscle insulin resistance: potential mechanisms and clinical relevance. Appl Physiol Nutr Metab 2008; 33:21-31. [DOI: 10.1139/h07-155] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The incidence of type 2 diabetes has increased dramatically over the past several decades and this trend is projected to continue into the foreseeable future. Skeletal muscle insulin resistance is thought to be a key development in the pathogenesis of type 2 diabetes. Given this fact, interventions that prevent or reverse impairments in skeletal muscle action can have profound effects on whole-body glucose homeostasis. Traditional approaches used in this regard include exercise, weight loss, and insulin-sensitizing drugs such as thiazolidinediones (TZDs). Although these interventions have proven effective in improving glucose homeostasis, there are adherence issues seen with lifestyle interventions and undesirable side effects have been reported with TZDs. With these points in mind, the development of alternative strategies to maintain or improve skeletal muscle insulin sensitivity is warranted. In this context, the purpose of the present review is to highlight the role of antioxidant compounds in the prevention and treatment of skeletal muscle insulin resistance. Specifically, we will briefly describe the mechanisms of insulin-stimulated skeletal muscle glucose uptake and the potential mediators of oxidative stress induced insulin resistance, highlight data suggesting that antioxidant compounds can have beneficial effects on skeletal muscle insulin action, and discuss potential mechanisms mediating this effect.
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Affiliation(s)
- David Wright
- Alberta Institute of Human Nutrition, 3-18b Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5
| | - Lindsey Sutherland
- Alberta Institute of Human Nutrition, 3-18b Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5
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43
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Lalli CA, Pauli JR, Prada PO, Cintra DE, Ropelle ER, Velloso LA, Saad MJA. Statin modulates insulin signaling and insulin resistance in liver and muscle of rats fed a high-fat diet. Metabolism 2008; 57:57-65. [PMID: 18078859 DOI: 10.1016/j.metabol.2007.07.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Accepted: 07/12/2007] [Indexed: 02/06/2023]
Abstract
Recent studies have shown that statins might have relevant effects on insulin resistance in animal models and in humans. However, the molecular mechanisms that account for this improvement in insulin sensitivity are not well established. The aim of the present study was to investigate the effect of a statin on insulin sensitivity and insulin signaling in liver and muscle of rats fed on a high-fat diet (HFD) for 4 weeks, treated or not with lovastatin during the last week. Our data show that treatment with lovastatin results in a marked improvement in insulin sensitivity characterized by an increase in glucose disappearance rate during the insulin tolerance test. This increase in insulin sensitivity was associated with an increase in insulin-induced insulin receptor (IR) tyrosine phosphorylation and, in parallel, a decrease in IR serine phosphorylation and association with PTP1B. Our data also show that lovastatin treatment was associated with an increase in insulin-stimulated insulin receptor substrate (IRS) 1/phosphatidylinositol 3-kinase/Akt pathway in the liver and muscle of HFD-fed rats in parallel with a decrease in the inflammatory pathway (c-jun N-terminal kinase and I kappa beta kinase (IKKbeta)/inhibitor of kappaB/nuclear factor kappaB) related to insulin resistance. In summary, statin treatment improves insulin sensitivity in HFD-fed rats by reversing the decrease in the insulin-stimulated IRS-1/phosphatidylinositol 3-kinase/Akt pathway in liver and muscle. The effect of statins on insulin action is further supported by our findings that HFD rats treated with statin show a reduction in IRS-1 serine phosphorylation, I kappa kinase (IKK)/inhibitor of kappaB/nuclear factor kappaB pathway, and c-jun N-terminal kinase activity, associated with an improvement in insulin action. Overall, these results provide important new insight into the mechanism of statin action in insulin sensitivity.
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Affiliation(s)
- Cristina Alba Lalli
- Departamento de Clínica Médica, FCM, Universidade Estadual de Campinas (UNICAMP) 13081-970 Campinas, SP, Brazil
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44
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Winder WW, Thomson DM. Cellular energy sensing and signaling by AMP-activated protein kinase. Cell Biochem Biophys 2007; 47:332-47. [PMID: 17652779 DOI: 10.1007/s12013-007-0008-7] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 12/25/2022]
Abstract
AMP-activated protein kinase (AMPK) is an energy sensing/signaling protein that, when activated, increases ATP production by stimulating glucose uptake and fatty acid oxidation while at the same time inhibiting ATP = consuming processes such as protein synthesis. Chronic activation of AMPK inhibits expression of lipogenic enzymes in the liver and enhances expression of mitochondrial oxidative enzymes in skeletal muscle. Deficiency of muscle LKB1, the upstream kinase of AMPK, results in greater fluctuation in energy charge during muscle contraction and decreased capacity for exercise at higher work rates. Because AMPK enhances both glucose uptake and fatty acid oxidation in skeletal muscle, it has become a target for prevention and treatment of type 2 diabetes and obesity.
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Affiliation(s)
- William W Winder
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA.
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45
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Cartee GD, Wojtaszewski JFP. Role of Akt substrate of 160 kDa in insulin-stimulated and contraction-stimulated glucose transport. Appl Physiol Nutr Metab 2007; 32:557-66. [PMID: 17510697 DOI: 10.1139/h07-026] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin and exercise, the most important physiological stimuli to increase glucose transport in skeletal muscle, trigger a redistribution of GLUT4 glucose transporter proteins from the cell interior to the cell surface, thereby increasing glucose transport capacity. The most distal insulin signaling protein that has been linked to GLUT4 translocation, Akt substrate of 160 kDa (AS160), becomes phosphorylated in insulin-stimulated 3T3-L1 adipocytes; this is important for insulin-stimulated GLUT4 translocation and glucose transport. Insulin also induces a rapid and dose-dependent increase in AS160 phosphorylation in skeletal muscle. Available data from skeletal muscle support the concepts developed in adipocytes with regard to the role AS160 plays in the regulation of insulin-stimulated glucose transport. In vivo exercise, in vitro contractions, or in situ contractions can also stimulate AS160 phosphorylation. AMP-activated protein kinase (AMPK) is likely important for phosphorylating AS160 in response to exercise/contractile activity, whereas Akt2 appears to be important for insulin-stimulated AS160 phosphorylation in muscle. Evidence of a role for AS160 in exercise/contraction-stimulated glucose uptake is currently inconclusive. The distinct signaling pathways that are stimulated by insulin and exercise/contraction converge at AS160. Although AS160 phosphorylation is apparently important for insulin-stimulated GLUT4 translocation and glucose transport, it is uncertain whether elevated AS160 phosphorylation plays a similar role with exercise/contraction.
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Affiliation(s)
- Gregory D Cartee
- Muscle Biology Laboratory, Division of Kinesiology, Room 3040E, 401 Washtenaw Avenue, University of Michigan, Ann Arbor, MI 48109-2214, USA.
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46
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Arias EB, Kim J, Funai K, Cartee GD. Prior exercise increases phosphorylation of Akt substrate of 160 kDa (AS160) in rat skeletal muscle. Am J Physiol Endocrinol Metab 2007; 292:E1191-200. [PMID: 17179389 DOI: 10.1152/ajpendo.00602.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The main purpose of this study was to determine whether the increased glucose transport (GT) found immediately postexercise (IPEX) or 4 h postexercise (4hPEX) is accompanied by increased phosphorylation of Akt substrate of 160 kDa (AS160, a protein regulator of GLUT4 translocation). Paired epitrochlearis muscles were dissected from rats (sedentary or IPEX, 2-h swim) and used to measure protein phosphorylation and insulin-independent GT. IPEX values exceeded sedentary values for GT and phosphorylations of AS160, AMP-activated protein kinase (pAMPK) and acetyl-CoA carboxylase (pACC) but not for AS160 abundance or phosphorylation of Akt serine (pSerAkt), Akt threonine (pThrAkt), or glycogen synthase kinase-3 (pGSK3). AS160 phosphorylation was significantly correlated with GT (R=0.801, P<0.01) and pAMPK (R=0.655, P<0.05). Muscles from other rats were studied 4hPEX along with sedentary controls. One muscle per rat was incubated without insulin, and the contralateral muscle was incubated with insulin. 4hPEX values exceeded sedentary values for insulin-stimulated GT. The elevated pAMPK and pACC found IPEX had reversed by 4hPEX. Insulin caused a significant increase in pSerAkt, pThrAkt, pGSK3, and AS160 phosphorylation with or without exercise. Exercise significantly increased AS160 phosphorylation, regardless of insulin, with unchanged AS160 abundance. Among the signaling proteins studied, insulin-stimulated GT was significantly correlated only with insulin-stimulated pThrAkt (R=0.720, P<0.0005). The results are consistent with a role for increased AS160 phosphorylation in the increased insulin-independent GT IPEX, and the exercise effects on AS160 phosphorylation and/or pThrAkt at 4hPEX are potentially relevant to the increased insulin-stimulated glucose transport at this time.
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Affiliation(s)
- Edward B Arias
- University of Michigan, Division of Kinesiology, Muscle Biology Laboratory, Ann Arbor, MI 48109-2214, USA
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47
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Burry M, Hawkins D, Spangenburg EE. Lengthening contractions differentially affect p70s6k phosphorylation compared to isometric contractions in rat skeletal muscle. Eur J Appl Physiol 2007; 100:409-15. [PMID: 17401575 DOI: 10.1007/s00421-007-0444-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2007] [Indexed: 02/01/2023]
Abstract
The purpose of this investigation was to determine if p70(s6k) phosphorylation is dependent on the mode of resistance exercise (e.g. isometric vs. lengthening). Two groups (n = 5 each) of Female Sprague Dawley rats, approximately 12 weeks old, were tested. Rats were anesthetized and indwelling electrodes used to stimulate the right hind limb muscles via the sciatic nerve. The tibialis anterior (TA) muscle of Group 1 rats were exposed to three sets of ten isometric resistance contractions while the TA of Group 2 rats were exposed to three sets of ten resistance contractions that involved lengthening. Contralateral TA muscles served as non-exercised controls. The TA muscle was harvested 6 h post exercise and then the rat was euthanized. Muscle samples were processed to compare p70(s6k) phosphorylation between groups. A single bout of TA contractions that involved muscle lengthening resulted in significantly (p < 0.05) higher levels of phospho-p70(s6k) six hours post exercise compared to controls and isometric contractions. The differences in total p70(s6k) six hours post exercise were not significantly different between groups. Results suggest that signal transduction pathways activated by isometric exercise may differ (i.e., a non-p70(s6k) activation pathway) from that activated by lengthening exercise.
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Affiliation(s)
- Martin Burry
- Biomedical Engineering Graduate Group, University of California, Davis, CA 95616, USA
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48
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Holland WL, Brozinick JT, Wang LP, Hawkins ED, Sargent KM, Liu Y, Narra K, Hoehn KL, Knotts TA, Siesky A, Nelson DH, Karathanasis SK, Fontenot GK, Birnbaum MJ, Summers SA. Inhibition of ceramide synthesis ameliorates glucocorticoid-, saturated-fat-, and obesity-induced insulin resistance. Cell Metab 2007; 5:167-79. [PMID: 17339025 DOI: 10.1016/j.cmet.2007.01.002] [Citation(s) in RCA: 922] [Impact Index Per Article: 54.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 12/12/2006] [Accepted: 01/10/2007] [Indexed: 02/07/2023]
Abstract
Insulin resistance occurs in 20%-25% of the human population, and the condition is a chief component of type 2 diabetes mellitus and a risk factor for cardiovascular disease and certain forms of cancer. Herein, we demonstrate that the sphingolipid ceramide is a common molecular intermediate linking several different pathological metabolic stresses (i.e., glucocorticoids and saturated fats, but not unsaturated fats) to the induction of insulin resistance. Moreover, inhibition of ceramide synthesis markedly improves glucose tolerance and prevents the onset of frank diabetes in obese rodents. Collectively, these data have two important implications. First, they indicate that different fatty acids induce insulin resistance by distinct mechanisms discerned by their reliance on sphingolipid synthesis. Second, they identify enzymes required for ceramide synthesis as therapeutic targets for combating insulin resistance caused by nutrient excess or glucocorticoid therapy.
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Affiliation(s)
- William L Holland
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA
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49
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Skov-Jensen C, Skovbro M, Flint A, Helge JW, Dela F. Contraction-mediated glucose uptake is increased in men with impaired glucose tolerance. Appl Physiol Nutr Metab 2007; 32:115-24. [PMID: 17332788 DOI: 10.1139/h06-098] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Exercise superimposed on insulin stimulation is shown to increase muscle glucose metabolism and these two stimuli have synergistic effects. The objective of this study was to investigate glucose infusion rates (GIR) in groups with a wide variation in terms of insulin sensitivity during insulin stimulation alone and with superimposed exercise. Patients with type 2 diabetes, subjects with impaired glucose tolerance (IGT), healthy controls, and endurance-trained subjects were studied. The groups were matched for age and lean body mass (LBM), and differed in peak oxygen uptake (VO2 peak), body fat percentage, body mass index (BMI), fasting plasma glucose concentration, and oral glucose-tolerance test (OGTT). Each subject underwent a two-step sequential hyperinsulinemic, euglycemic clamp. During the last 30 min of the 2nd clamp step, subjects exercised on a bicycle at 43% ± 2% of VO2 peak. In agreement with the OGTT data, the presence of different GIR during insulin stimulation alone demonstrated varying levels of insulin sensitivity between groups. However, the impairment of GIR in IGT observed during insulin stimulation alone was abolished compared to controls when exercise was superimposed on insulin stimulation. Humans with IGT are resistant to insulin-stimulated but not to exercise-induced glucose uptake.
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Affiliation(s)
- Camilla Skov-Jensen
- Copenhagen Muscle Research Centre, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Kbh N, Denmark
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50
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Sakamoto K, Arnolds DE, Fujii N, Kramer HF, Hirshman MF, Goodyear LJ. Role of Akt2 in contraction-stimulated cell signaling and glucose uptake in skeletal muscle. Am J Physiol Endocrinol Metab 2006; 291:E1031-7. [PMID: 16803855 DOI: 10.1152/ajpendo.00204.2006] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The serine/threonine kinase Akt/PKB plays diverse roles in cells, and genetic studies have indicated distinct roles for the three Akt isoforms expressed in mammalian cells and tissues. Akt2 is a key signaling intermediate for insulin-stimulated glucose uptake and glycogen synthesis in skeletal muscle. Akt2 has also been shown to be activated by exercise and muscle contraction in both rodents and humans. In this study, we used Akt2 knockout mice to explore the role of Akt2 in exercise-stimulated glucose uptake and glycogen synthesis as well as intracellular signaling pathways that regulate glycogen metabolism in skeletal muscle. We found that Akt2 deficiency does not affect basal or exercise-stimulated glucose uptake or intracellular glycogen content in the soleus muscle. In addition, lack of Akt2 did not result in alterations in basal Akt Thr(308) or basal and contraction-stimulated glycogen synthase kinase-3beta (GSK-3beta) Ser(9) phosphorylation, glycogen synthase phosphorylation, or glycogen synthase activity. In contrast, in situ contraction failed to elicit normal increases in Akt T-loop Thr(308) phosphorylation and GSK-3alpha Ser(21) phosphorylation in tibialis anterior muscles from Akt2-deficient animals. Our data establish a key role for Akt2 in the regulation of GSK-3alpha Ser(21) phosphorylation with contraction and add genetic evidence to support the separation of the intracellular pathways regulated by insulin and exercise that converge on glucose uptake and glycogen synthesis in skeletal muscle.
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Affiliation(s)
- Kei Sakamoto
- The Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
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