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Wilkerson JL, Tatum SM, Holland WL, Summers SA. Ceramides are fuel gauges on the drive to cardiometabolic disease. Physiol Rev 2024; 104:1061-1119. [PMID: 38300524 DOI: 10.1152/physrev.00008.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/02/2024] Open
Abstract
Ceramides are signals of fatty acid excess that accumulate when a cell's energetic needs have been met and its nutrient storage has reached capacity. As these sphingolipids accrue, they alter the metabolism and survival of cells throughout the body including in the heart, liver, blood vessels, skeletal muscle, brain, and kidney. These ceramide actions elicit the tissue dysfunction that underlies cardiometabolic diseases such as diabetes, coronary artery disease, metabolic-associated steatohepatitis, and heart failure. Here, we review the biosynthesis and degradation pathways that maintain ceramide levels in normal physiology and discuss how the loss of ceramide homeostasis drives cardiometabolic pathologies. We highlight signaling nodes that sense small changes in ceramides and in turn reprogram cellular metabolism and stimulate apoptosis. Finally, we evaluate the emerging therapeutic utility of these unique lipids as biomarkers that forecast disease risk and as targets of ceramide-lowering interventions that ameliorate disease.
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Affiliation(s)
- Joseph L Wilkerson
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - Sean M Tatum
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - William L Holland
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
| | - Scott A Summers
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, United States
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2
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Seal A, Hughes M, Wei F, Pugazhendhi AS, Ngo C, Ruiz J, Schwartzman JD, Coathup MJ. Sphingolipid-Induced Bone Regulation and Its Emerging Role in Dysfunction Due to Disease and Infection. Int J Mol Sci 2024; 25:3024. [PMID: 38474268 DOI: 10.3390/ijms25053024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/02/2024] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
The human skeleton is a metabolically active system that is constantly regenerating via the tightly regulated and highly coordinated processes of bone resorption and formation. Emerging evidence reveals fascinating new insights into the role of sphingolipids, including sphingomyelin, sphingosine, ceramide, and sphingosine-1-phosphate, in bone homeostasis. Sphingolipids are a major class of highly bioactive lipids able to activate distinct protein targets including, lipases, phosphatases, and kinases, thereby conferring distinct cellular functions beyond energy metabolism. Lipids are known to contribute to the progression of chronic inflammation, and notably, an increase in bone marrow adiposity parallel to elevated bone loss is observed in most pathological bone conditions, including aging, rheumatoid arthritis, osteoarthritis, and osteomyelitis. Of the numerous classes of lipids that form, sphingolipids are considered among the most deleterious. This review highlights the important primary role of sphingolipids in bone homeostasis and how dysregulation of these bioactive metabolites appears central to many chronic bone-related diseases. Further, their contribution to the invasion, virulence, and colonization of both viral and bacterial host cell infections is also discussed. Many unmet clinical needs remain, and data to date suggest the future use of sphingolipid-targeted therapy to regulate bone dysfunction due to a variety of diseases or infection are highly promising. However, deciphering the biochemical and molecular mechanisms of this diverse and extremely complex sphingolipidome, both in terms of bone health and disease, is considered the next frontier in the field.
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Affiliation(s)
- Anouska Seal
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA
| | - Megan Hughes
- School of Biosciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Fei Wei
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Abinaya S Pugazhendhi
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Christopher Ngo
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Jonathan Ruiz
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | | | - Melanie J Coathup
- Biionix Cluster, University of Central Florida, Orlando, FL 32827, USA
- College of Medicine, University of Central Florida, Orlando, FL 32827, USA
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3
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Lee SE, Lim ES, Yoon JW, Park HJ, Kim SH, Lee HB, Han DH, Kim EY, Park SP. Cell starvation regulates ceramide-induced autophagy in mouse preimplantation embryo development. Cells Dev 2023; 175:203859. [PMID: 37271244 DOI: 10.1016/j.cdev.2023.203859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 05/23/2023] [Accepted: 05/31/2023] [Indexed: 06/06/2023]
Abstract
Ceramide induces autophagy upon starvation via downregulation of nutrient transporters. To elucidate the mechanism by which starvation regulates autophagy in mouse embryos, the present study investigated nutrient transporter expression and the effect of C2-ceramide on in vitro embryo development, apoptosis, and autophagy. The transcript levels of the glucose transporters Glut1 and Glut3 were high at the 1- and 2-cell stages, and gradually decreased at the morula and blastocyst (BL) stages. Similarly, expression of the amino acid transporters L-type amino transporter-1 (LAT-1) and 4F2 heavy chain (4F2hc) gradually decreased from the zygote to the BL stage. Upon ceramide treatment, expression of Glut1, Glut3, LAT-1, and 4F2hc was significantly reduced at the BL stage, while expression of the autophagy-related genes Atg5, LC3, and Gabarap and synthesis of LC3 were significantly induced. Ceramide-treated embryos exhibited significantly reduced developmental rates and total cell numbers per blastocyst, and increased levels of apoptosis and expression of Bcl2l1 and Casp3 at the BL stage. Ceramide treatment significantly decreased the average mitochondrial DNA copy number and mitochondrial area at the BL stage. In addition, ceramide treatment significantly decreased mTOR expression. These results suggest that ceramide-induced autophagy promotes apoptosis by following downregulation of nutrient transporters during mouse embryogenesis.
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Affiliation(s)
- Seung-Eun Lee
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - Eun-Seo Lim
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - Jae-Wook Yoon
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - Hyo-Jin Park
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - So-Hee Kim
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - Han-Bi Lee
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - Dong-Hun Han
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea
| | - Eun-Young Kim
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Mirae Cell Bio, 1502 isbiz-tower 147, Seongsui-ro, Seongdong-gu, Seoul 04795, Republic of Korea
| | - Se-Pill Park
- Stem Cell Research Center, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea; Mirae Cell Bio, 1502 isbiz-tower 147, Seongsui-ro, Seongdong-gu, Seoul 04795, Republic of Korea; Department of Bio Medical Informatics, College of Applied Life Sciences, Jeju National University, 102 Jejudaehak-ro, Jeju, Jeju Special Self-Governing Province 63243, Republic of Korea.
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Sanches JM, Zhao LN, Salehi A, Wollheim CB, Kaldis P. Pathophysiology of type 2 diabetes and the impact of altered metabolic interorgan crosstalk. FEBS J 2023; 290:620-648. [PMID: 34847289 DOI: 10.1111/febs.16306] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 10/14/2021] [Accepted: 11/29/2021] [Indexed: 02/06/2023]
Abstract
Diabetes is a complex and multifactorial disease that affects millions of people worldwide, reducing the quality of life significantly, and results in grave consequences for our health care system. In type 2 diabetes (T2D), the lack of β-cell compensatory mechanisms overcoming peripherally developed insulin resistance is a paramount factor leading to disturbed blood glucose levels and lipid metabolism. Impaired β-cell functions and insulin resistance have been studied extensively resulting in a good understanding of these pathways but much less is known about interorgan crosstalk, which we define as signaling between tissues by secreted factors. Besides hormones and organokines, dysregulated blood glucose and long-lasting hyperglycemia in T2D is associated with changes in metabolism with metabolites from different tissues contributing to the development of this disease. Recent data suggest that metabolites, such as lipids including free fatty acids and amino acids, play important roles in the interorgan crosstalk during the development of T2D. In general, metabolic remodeling affects physiological homeostasis and impacts the development of T2D. Hence, we highlight the importance of metabolic interorgan crosstalk in this review to gain enhanced knowledge of the pathophysiology of T2D, which may lead to new therapeutic approaches to treat this disease.
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Affiliation(s)
| | - Li Na Zhao
- Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Albert Salehi
- Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Claes B Wollheim
- Department of Clinical Sciences, Lund University, Malmö, Sweden.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Philipp Kaldis
- Department of Clinical Sciences, Lund University, Malmö, Sweden
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Varre JV, Holland WL, Summers SA. You aren't IMMUNE to the ceramides that accumulate in cardiometabolic disease. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159125. [PMID: 35218934 DOI: 10.1016/j.bbalip.2022.159125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 02/14/2022] [Indexed: 02/06/2023]
Abstract
Obesity leads to persistent increases in immune responses that contribute to cardiometabolic pathologies such as diabetes and cardiovascular disease. Pro-inflammatory macrophages infiltrate the expanding fat mass, which leads to increased production of cytokines such as tumor necrosis factor-alpha. Moreover, saturated fatty acids enhance signaling through the toll-like receptors involved in innate immunity. Herein we discuss the evidence that ceramides-which are intermediates in the biosynthetic pathway that produces sphingolipids-are essential intermediates that link these inflammatory signals to impaired tissue function. We discuss the mechanisms linking these immune insults to ceramide production and review the numerous ceramide actions that alter cellular metabolism, induce oxidative stress, and stimulate apoptosis. Lastly, we evaluate the correlation of ceramides in humans with inflammation-linked cardiometabolic disease and discuss preclinical studies which suggest that ceramide-lowering interventions may be an effective strategy to treat or prevent such maladies.
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Brusatori M, Wood MH, Tucker SC, Maddipati KR, Koya SK, Auner GW, Honn KV, Seyoum B. Ceramide changes in abdominal subcutaneous and visceral adipose tissue among diabetic and nondiabetic patients. J Diabetes 2022; 14:271-281. [PMID: 35470585 PMCID: PMC9060146 DOI: 10.1111/1753-0407.13262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/31/2022] [Accepted: 02/15/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND This study profiles ceramides extracted from visceral and subcutaneous adipose tissue of human subjects by liquid chromatography-mass spectrometry to determine a correlation with status of diabetes and gender. METHODS Samples of visceral and abdominal wall subcutaneous adipose tissue (n = 36 and n = 31, respectively) were taken during laparoscopic surgery from 36 patients (14 nondiabetic, 22 diabetic and prediabetic) undergoing bariatric surgery with a body mass index (BMI) >35 kg/m2 with ≥1 existing comorbidity or BMI ≥40 kg/m2 . Sphingolipids were extracted and analyzed using liquid chromatography-mass spectrometry. RESULTS After logarithm 2 conversion, paired analysis of visceral to subcutaneous tissue showed differential accumulation of Cer(d18:1/16:0), Cer(d18:1/18:0), and Cer(d18:1/24:1) in visceral tissue of prediabetic/diabetic female subjects, but not in males. Within-tissue analysis showed higher mean levels of ceramide species linked to insulin resistance, such as Cer(d18:1/18:0) and Cer(d18:1/16:0), in visceral tissue of prediabetic/diabetic patients compared with nondiabetic subjects and higher content of Cer(d18:1/14:0) in subcutaneous tissue of insulin-resistant female patients compared with prediabetic/diabetic males. Statistically significant differences in mean levels of ceramide species between insulin-resistant African American and insulin-resistant Caucasian patients were not evident in visceral or subcutaneous tissue. CONCLUSIONS Analysis of ceramides is important for developing a better understanding of biological processes underlying type 2 diabetes, metabolic syndrome, and obesity. Knowledge of the accumulated ceramides/dihydroceramides may reflect on the prelipolytic state that leads the lipotoxic phase of insulin resistance and may shed light on the predisposition to insulin resistance by gender.
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Affiliation(s)
- Michelle Brusatori
- Michael and Marian Ilitch Department of SurgerySchool of Medicine, Wayne State UniversityDetroitMichiganUSA
- Smart Sensors and Integrated Microsystems ProgramWayne State UniversityDetroitMichiganUSA
| | - Michael H. Wood
- Michael and Marian Ilitch Department of SurgerySchool of Medicine, Wayne State UniversityDetroitMichiganUSA
- Harper Bariatric Medicine InstituteHarper University Hospital, Detroit Medical CenterDetroitMichiganUSA
| | - Stephanie C. Tucker
- Department of PathologyBioactive Lipids Research Program and Lipidomics Core Facility, Wayne State UniversityDetroitMichiganUSA
| | - Krishna Rao Maddipati
- Department of PathologyBioactive Lipids Research Program and Lipidomics Core Facility, Wayne State UniversityDetroitMichiganUSA
| | - S. Kiran Koya
- Michael and Marian Ilitch Department of SurgerySchool of Medicine, Wayne State UniversityDetroitMichiganUSA
- Smart Sensors and Integrated Microsystems ProgramWayne State UniversityDetroitMichiganUSA
| | - Gregory W. Auner
- Michael and Marian Ilitch Department of SurgerySchool of Medicine, Wayne State UniversityDetroitMichiganUSA
- Smart Sensors and Integrated Microsystems ProgramWayne State UniversityDetroitMichiganUSA
| | - Kenneth V. Honn
- Department of PathologyBioactive Lipids Research Program and Lipidomics Core Facility, Wayne State UniversityDetroitMichiganUSA
| | - Berhane Seyoum
- Division of EndocrinologyWayne State University, School of MedicineDetroitMichiganUSA
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7
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Fakhr Y, Brindley DN, Hemmings DG. Physiological and pathological functions of sphingolipids in pregnancy. Cell Signal 2021; 85:110041. [PMID: 33991614 DOI: 10.1016/j.cellsig.2021.110041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 01/12/2023]
Abstract
Signaling by the bioactive sphingolipid, sphingosine 1-phosphate (S1P), and its precursors are emerging areas in pregnancy research. S1P and ceramide levels increase towards end of gestation, suggesting a physiological role in parturition. However, high levels of circulating S1P and ceramide are correlated with pregnancy disorders such as preeclampsia, gestational diabetes mellitus and intrauterine growth restriction. Expression of placental and decidual enzymes that metabolize S1P and S1P receptors are also dysregulated during pregnancy complications. In this review, we provide an in-depth examination of the signaling mechanism of S1P and ceramide in various reproductive tissues during gestation. These factors determine implantation and early pregnancy success by modulating corpus luteum function from progesterone production to luteolysis through to apoptosis. We also highlight the role of S1P through receptor signaling in inducing decidualization and angiogenesis in the decidua, as well as regulating extravillous trophoblast migration to anchor the placenta into the uterine wall. Recent advances on the role of the S1P:ceramide rheostat in controlling the fate of villous trophoblasts and the role of S1P as a negative regulator of trophoblast syncytialization to a multinucleated placental barrier are discussed. This review also explores the role of S1P in anti-inflammatory and pro-inflammatory signaling, its role as a vasoconstrictor, and the effects of S1P metabolizing enzymes and receptors in pregnancy.
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Affiliation(s)
- Yuliya Fakhr
- Department of Obstetrics and Gynecology, University of Alberta, Edmonton, AB T6G 2S2, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - David N Brindley
- Women and Children's Health Research Institute, University of Alberta, Edmonton, AB T6G 1C9, Canada; Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2S2, Canada; Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - Denise G Hemmings
- Department of Obstetrics and Gynecology, University of Alberta, Edmonton, AB T6G 2S2, Canada; Women and Children's Health Research Institute, University of Alberta, Edmonton, AB T6G 1C9, Canada; Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB T6G 2E1, Canada; Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, AB T6G 2S2, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
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Abstract
The global prevalence of metabolic diseases such as type 2 diabetes mellitus, steatohepatitis, myocardial infarction, and stroke has increased dramatically over the past two decades. These obesity-fueled disorders result, in part, from the aberrant accumulation of harmful lipid metabolites in tissues not suited for lipid storage (e.g., the liver, vasculature, heart, and pancreatic beta-cells). Among the numerous lipid subtypes that accumulate, sphingolipids such as ceramides are particularly impactful, as they elicit the selective insulin resistance, dyslipidemia, and ultimately cell death that underlie nearly all metabolic disorders. This review summarizes recent findings on the regulatory pathways controlling ceramide production, the molecular mechanisms linking the lipids to these discrete pathogenic events, and exciting attempts to develop therapeutics to reduce ceramide levels to combat metabolic disease.
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Affiliation(s)
- Bhagirath Chaurasia
- Department of Internal Medicine, Division of Endocrinology, Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA;
| | - Scott A Summers
- Department of Nutrition and Integrative Physiology and the Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, Utah 84112, USA;
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9
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Barra NG, Henriksbo BD, Anhê FF, Schertzer JD. The NLRP3 inflammasome regulates adipose tissue metabolism. Biochem J 2020; 477:1089-107. [PMID: 32202638 DOI: 10.1042/BCJ20190472] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 12/27/2022]
Abstract
Adipose tissue regulates metabolic homeostasis by participating in endocrine and immune responses in addition to storing and releasing lipids from adipocytes. Obesity skews adipose tissue adipokine responses and degrades the coordination of adipocyte lipogenesis and lipolysis. These defects in adipose tissue metabolism can promote ectopic lipid deposition and inflammation in insulin-sensitive tissues such as skeletal muscle and liver. Sustained caloric excess can expand white adipose tissue to a point of maladaptation exacerbating both local and systemic inflammation. Multiple sources, instigators and propagators of adipose tissue inflammation occur during obesity. Cross-talk between professional immune cells (i.e. macrophages) and metabolic cells (i.e. adipocytes) promote adipose tissue inflammation during metabolic stress (i.e. metaflammation). Metabolic stress and endogenous danger signals can engage pathogen recognition receptors (PRRs) of the innate immune system thereby activating pro-inflammatory and stress pathways in adipose tissue. The Nod-like receptor protein 3 (NLRP3) inflammasome can act as a metabolic danger sensor to a wide range of pathogen- and damage-associated molecular patterns (PAMPs and DAMPs). Activation of the NLRP3 inflammasome facilitates caspase-1 dependent production of the pro-inflammatory cytokines IL-1β and IL-18. Activation of the NLRP3 inflammasome can promote inflammation and pyroptotic cell death, but caspase-1 is also involved in adipogenesis. This review discusses the role of the NLRP3 inflammasome in adipose tissue immunometabolism responses relevant to metabolic disease. Understanding the potential sources of NLRP3 activation and consequences of NLRP3 effectors may reveal therapeutic opportunities to break or fine-tune the connection between metabolism and inflammation in adipose tissue during obesity.
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10
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Lair B, Laurens C, Van Den Bosch B, Moro C. Novel Insights and Mechanisms of Lipotoxicity-Driven Insulin Resistance. Int J Mol Sci 2020; 21:E6358. [PMID: 32887221 PMCID: PMC7504171 DOI: 10.3390/ijms21176358] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 08/27/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023] Open
Abstract
A large number of studies reported an association between elevated circulating and tissue lipid content and metabolic disorders in obesity, type 2 diabetes (T2D) and aging. This state of uncontrolled tissue lipid accumulation has been called lipotoxicity. It was later shown that excess lipid flux is mainly neutralized within lipid droplets as triglycerides, while several bioactive lipid species such as diacylglycerols (DAGs), ceramides and their derivatives have been mechanistically linked to the pathogenesis of insulin resistance (IR) by antagonizing insulin signaling and action in metabolic organs such as the liver and skeletal muscle. Skeletal muscle and the liver are the main sites of glucose disposal in the body and IR in these tissues plays a pivotal role in the development of T2D. In this review, we critically examine recent literature supporting a causal role of DAGs and ceramides in the development of IR. A particular emphasis is placed on transgenic mouse models with modulation of total DAG and ceramide pools, as well as on modulation of specific subspecies, in relation to insulin sensitivity. Collectively, although a wide number of studies converge towards the conclusion that both DAGs and ceramides cause IR in metabolic organs, there are still some uncertainties on their mechanisms of action. Recent studies reveal that subcellular localization and acyl chain composition are determinants in the biological activity of these lipotoxic lipids and should be further examined.
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Affiliation(s)
- Benjamin Lair
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, 31432 Toulouse, France; (B.L.); (C.L.); (B.V.D.B.)
- University of Toulouse, Paul Sabatier University, 31330 Toulouse, France
| | - Claire Laurens
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, 31432 Toulouse, France; (B.L.); (C.L.); (B.V.D.B.)
- University of Toulouse, Paul Sabatier University, 31330 Toulouse, France
| | - Bram Van Den Bosch
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, 31432 Toulouse, France; (B.L.); (C.L.); (B.V.D.B.)
- University of Toulouse, Paul Sabatier University, 31330 Toulouse, France
| | - Cedric Moro
- INSERM, UMR1048, Institute of Metabolic and Cardiovascular Diseases, 31432 Toulouse, France; (B.L.); (C.L.); (B.V.D.B.)
- University of Toulouse, Paul Sabatier University, 31330 Toulouse, France
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11
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Park WJ, Song JH, Kim GT, Park TS. Ceramide and Sphingosine 1-Phosphate in Liver Diseases. Mol Cells 2020; 43:419-430. [PMID: 32392908 PMCID: PMC7264474 DOI: 10.14348/molcells.2020.0054] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/06/2020] [Accepted: 04/19/2020] [Indexed: 12/12/2022] Open
Abstract
The liver is an important organ in the regulation of glucose and lipid metabolism. It is responsible for systemic energy homeostasis. When energy need exceeds the storage capacity in the liver, fatty acids are shunted into nonoxidative sphingolipid biosynthesis, which increases the level of cellular ceramides. Accumulation of ceramides alters substrate utilization from glucose to lipids, activates triglyceride storage, and results in the development of both insulin resistance and hepatosteatosis, increasing the likelihood of major metabolic diseases. Another sphingolipid metabolite, sphingosine 1-phosphate (S1P) is a bioactive signaling molecule that acts via S1P-specific G protein coupled receptors. It regulates many cellular and physiological events. Since an increase in plasma S1P is associated with obesity, it seems reasonable that recent studies have provided evidence that S1P is linked to lipid pathophysiology, including hepatosteatosis and fibrosis. Herein, we review recent findings on ceramides and S1P in obesity-mediated liver diseases and the therapeutic potential of these sphingolipid metabolites.
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Affiliation(s)
- Woo-Jae Park
- Department of Biochemistry, College of Medicine, Gachon University, Incheon 2999, Korea
| | - Jae-Hwi Song
- Department of Life Science, Gachon University, Seongnam 1310, Korea
| | - Goon-Tae Kim
- Department of Life Science, Gachon University, Seongnam 1310, Korea
| | - Tae-Sik Park
- Department of Life Science, Gachon University, Seongnam 1310, Korea
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12
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Abstract
Ceramides are minor components of the hepatic lipidome that have major effects on liver function. These products of lipid and protein metabolism accumulate when the energy needs of the hepatocyte have been met and its storage capacity is full, such that free fatty acids start to couple to the sphingoid backbone rather than the glycerol moiety that is the scaffold for glycerolipids (e.g., triglycerides) or the carnitine moiety that shunts them into mitochondria. As ceramides accrue, they initiate actions that protect cells from acute increases in detergent-like fatty acids; for example, they alter cellular substrate preference from glucose to lipids and they enhance triglyceride storage. When prolonged, these ceramide actions cause insulin resistance and hepatic steatosis, 2 of the underlying drivers of cardiometabolic diseases. Herein the author discusses the mechanisms linking ceramides to the development of insulin resistance, hepatosteatosis and resultant cardiometabolic disorders.
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Affiliation(s)
- Scott A Summers
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
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13
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Abstract
Ceramides are products of metabolism that accumulate in individuals with obesity or dyslipidaemia and alter cellular processes in response to fuel surplus. Their actions, when prolonged, elicit the tissue dysfunction that underlies diabetes and heart disease. Here, we review the history of research on these enigmatic molecules, exploring their discovery and mechanisms of action, the evolutionary pressures that have given them their unique attributes and the potential of ceramide-reduction therapies as treatments for cardiometabolic disease.
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Affiliation(s)
- Scott A Summers
- Department of Nutrition and Integrative Physiology and the Diabetes and Metabolism Center, University of Utah, Salt Lake City, UT, USA.
| | - Bhagirath Chaurasia
- Department of Nutrition and Integrative Physiology and the Diabetes and Metabolism Center, University of Utah, Salt Lake City, UT, USA
| | - William L Holland
- Department of Nutrition and Integrative Physiology and the Diabetes and Metabolism Center, University of Utah, Salt Lake City, UT, USA
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Abstract
Ceramides are bioactive sphingolipids that support the structure of the plasma membrane and mediate numerous cell-signaling events in eukaryotic cells. The finding that ceramides act as second messengers transducing cellular signals has attracted substantial attention in several fields of Biology. Since all cells contain lipid plasma membranes, the impact of various ceramides, ceramide synthases, ceramide metabolites, and other sphingolipids has been implicated in a vast range of cellular functions including, migration, proliferation, response to external stimuli, and death. The roles of lipids in these functions widely differ among the diverse cell types. Herein, we discuss the roles of ceramides and other sphingolipids in mediating the function of various immune cells; particularly dendritic cells, neutrophils, and macrophages. In addition, we highlight the main studies describing effects of ceramides in inflammation, specifically in various inflammatory settings including insulin resistance, graft-versus-host disease, immune suppression in cancer, multiple sclerosis, and inflammatory bowel disease.
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Affiliation(s)
- Sabrin Albeituni
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Johnny Stiban
- Department of Biology and Biochemistry, Birzeit University, West Bank, Palestine.
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15
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Abstract
The 1921 discovery of insulin was a Big Bang from which a vast and expanding universe of research into insulin action and resistance has issued. In the intervening century, some discoveries have matured, coalescing into solid and fertile ground for clinical application; others remain incompletely investigated and scientifically controversial. Here, we attempt to synthesize this work to guide further mechanistic investigation and to inform the development of novel therapies for type 2 diabetes (T2D). The rational development of such therapies necessitates detailed knowledge of one of the key pathophysiological processes involved in T2D: insulin resistance. Understanding insulin resistance, in turn, requires knowledge of normal insulin action. In this review, both the physiology of insulin action and the pathophysiology of insulin resistance are described, focusing on three key insulin target tissues: skeletal muscle, liver, and white adipose tissue. We aim to develop an integrated physiological perspective, placing the intricate signaling effectors that carry out the cell-autonomous response to insulin in the context of the tissue-specific functions that generate the coordinated organismal response. First, in section II, the effectors and effects of direct, cell-autonomous insulin action in muscle, liver, and white adipose tissue are reviewed, beginning at the insulin receptor and working downstream. Section III considers the critical and underappreciated role of tissue crosstalk in whole body insulin action, especially the essential interaction between adipose lipolysis and hepatic gluconeogenesis. The pathophysiology of insulin resistance is then described in section IV. Special attention is given to which signaling pathways and functions become insulin resistant in the setting of chronic overnutrition, and an alternative explanation for the phenomenon of ‟selective hepatic insulin resistanceˮ is presented. Sections V, VI, and VII critically examine the evidence for and against several putative mediators of insulin resistance. Section V reviews work linking the bioactive lipids diacylglycerol, ceramide, and acylcarnitine to insulin resistance; section VI considers the impact of nutrient stresses in the endoplasmic reticulum and mitochondria on insulin resistance; and section VII discusses non-cell autonomous factors proposed to induce insulin resistance, including inflammatory mediators, branched-chain amino acids, adipokines, and hepatokines. Finally, in section VIII, we propose an integrated model of insulin resistance that links these mediators to final common pathways of metabolite-driven gluconeogenesis and ectopic lipid accumulation.
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Affiliation(s)
- Max C Petersen
- Departments of Internal Medicine and Cellular & Molecular Physiology, Howard Hughes Medical Institute, Yale University School of Medicine , New Haven, Connecticut
| | - Gerald I Shulman
- Departments of Internal Medicine and Cellular & Molecular Physiology, Howard Hughes Medical Institute, Yale University School of Medicine , New Haven, Connecticut
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Bandet CL, Mahfouz R, Véret J, Sotiropoulos A, Poirier M, Giussani P, Campana M, Philippe E, Blachnio-Zabielska A, Ballaire R, Le Liepvre X, Bourron O, Berkeš D, Górski J, Ferré P, Le Stunff H, Foufelle F, Hajduch E. Ceramide Transporter CERT Is Involved in Muscle Insulin Signaling Defects Under Lipotoxic Conditions. Diabetes 2018; 67:1258-1271. [PMID: 29759974 DOI: 10.2337/db17-0901] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 04/29/2018] [Indexed: 11/13/2022]
Abstract
One main mechanism of insulin resistance (IR), a key feature of type 2 diabetes, is the accumulation of saturated fatty acids (FAs) in the muscles of obese patients with type 2 diabetes. Understanding the mechanism that underlies lipid-induced IR is an important challenge. Saturated FAs are metabolized into lipid derivatives called ceramides, and their accumulation plays a central role in the development of muscle IR. Ceramides are produced in the endoplasmic reticulum (ER) and transported to the Golgi apparatus through a transporter called CERT, where they are converted into various sphingolipid species. We show that CERT protein expression is reduced in all IR models studied because of a caspase-dependent cleavage. Inhibiting CERT activity in vitro potentiates the deleterious action of lipotoxicity on insulin signaling, whereas overexpression of CERT in vitro or in vivo decreases muscle ceramide content and improves insulin signaling. In addition, inhibition of caspase activity prevents ceramide-induced insulin signaling defects in C2C12 muscle cells. Altogether, these results demonstrate the importance of physiological ER-to-Golgi ceramide traffic to preserve muscle cell insulin signaling and identify CERT as a major actor in this process.
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Affiliation(s)
- Cécile L Bandet
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Rana Mahfouz
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Julien Véret
- Université Paris-Diderot, Unité de biologie fonctionnelle et adaptative, CNRS UMR 8251, Paris, France
| | | | - Maxime Poirier
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Paola Giussani
- Department of Medical Biotechnology and Translational Medicine, Università di Milano, LITA Segrate, Milan, Italy
| | - Mélanie Campana
- Université Paris-Diderot, Unité de biologie fonctionnelle et adaptative, CNRS UMR 8251, Paris, France
| | - Erwann Philippe
- Université Paris-Diderot, Unité de biologie fonctionnelle et adaptative, CNRS UMR 8251, Paris, France
| | - Agnieszka Blachnio-Zabielska
- Departments of Physiology and Hygiene, Epidemiology and Metabolic Disorders, Medical University of Bialystok, Bialystok, Poland
| | - Raphaëlle Ballaire
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Xavier Le Liepvre
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Olivier Bourron
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
- Assistance Publique-Hôpitaux de Paris, Département de Diabétologie et Maladies métaboliques, Hôpital Pitié-Salpêtrière, Paris, France
| | - Dušan Berkeš
- Department of Organic Chemistry, Slovak University of Technology, Bratislava, Slovakia
| | - Jan Górski
- Departments of Physiology and Hygiene, Epidemiology and Metabolic Disorders, Medical University of Bialystok, Bialystok, Poland
| | - Pascal Ferré
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Hervé Le Stunff
- Université Paris-Diderot, Unité de biologie fonctionnelle et adaptative, CNRS UMR 8251, Paris, France
- UMR 9197 Institut des Neurosciences Paris Saclay (Neuro-PSI), Université Paris-Saclay, Saclay, France
| | - Fabienne Foufelle
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
| | - Eric Hajduch
- INSERM UMRS 1138, Sorbonne Université, Sorbonne Paris Cité, Université Paris Descartes, Université Paris Diderot, Centre de Recherche des Cordeliers, Paris, France
- Institut Hospitalo-Universitaire ICAN, Paris, France
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Li J, Chen T, Li K, Yan H, Li X, Yang Y, Zhang Y, Su B, Li F. Neurolytic celiac plexus block enhances skeletal muscle insulin signaling and attenuates insulin resistance in GK rats. Exp Ther Med 2016; 11:2033-2041. [PMID: 27168847 DOI: 10.3892/etm.2016.3087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/04/2015] [Indexed: 12/15/2022] Open
Abstract
Non-insulin-dependent diabetes mellitus (NIDDM) is associated with chronic inflammatory activity and disrupted insulin signaling, leading to insulin resistance (IR). The present study investigated the benefits of neurolytic celiac plexus block (NCPB) on IR in a rat NIDDM model. Goto-Kakizaki rats fed a high-fat, high-glucose diet to induce signs of NIDDM were randomly divided into NCPB and control groups; these received daily bilateral 0.5% lidocaine or 0.9% saline injections into the celiac plexus, respectively. Following 14 and 28 daily injections, rats were subject to oral glucose tolerance tests (OGTTs) or sacrificed for the analysis of serum free fatty acids (FFAs), serum inflammatory cytokines and skeletal muscle insulin signaling. Compared with controls, rats in the NCPB group demonstrated significantly (P<0.05) lower baseline, 60-min and 120-min OGTT values, lower 120-min serum insulin, lower IR [higher insulin sensitivity index (ISI1) and lower ISI2) and lower serum FFAs, tumor necrosis factor-α, interleukin (IL)-1β and IL-6. Conversely, NCPB rats exhibited higher basal and insulin-stimulated skeletal muscle glucose uptake and higher skeletal muscle insulin receptor substrate-1 (IRS-1) and glucose transporter type 4 expression. There were no differences between the groups in insulin receptor β (Rβ) or Akt expression; however Rβ-Y1162/Y1163 and Akt-S473 phosphorylation levels were higher and IRS-1-S307 phosphorylation were lower in NCPB rats than in the controls. These results indicate that NCPB improved insulin signaling and reduced IR, possibly by inhibiting inflammatory cytokine release.
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Affiliation(s)
- Jun Li
- Department of Anesthesiology, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Tao Chen
- General Surgery Center, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Kun Li
- Medical Laboratory Center, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Hongtao Yan
- General Surgery Center, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Xiaowei Li
- Department of Urology, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Yun Yang
- Medical Laboratory Center, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Yulan Zhang
- Department of Anesthesiology, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
| | - Bingyin Su
- Development and Regeneration Key Laboratory of Sichuan, Chengdu Medical College, Chengdu, Sichuan 610083, P.R. China
| | - Fuxiang Li
- Department of ICU, Chengdu Military General Hospital, Chengdu, Sichuan 610083, P.R. China
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18
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Rumberger JM, Arch JRS, Green A. Butyrate and other short-chain fatty acids increase the rate of lipolysis in 3T3-L1 adipocytes. PeerJ 2014; 2:e611. [PMID: 25320679 PMCID: PMC4193401 DOI: 10.7717/peerj.611] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 09/16/2014] [Indexed: 12/15/2022] Open
Abstract
We determined the effect of butyrate and other short-chain fatty acids (SCFA) on rates of lipolysis in 3T3-L1 adipocytes. Prolonged treatment with butyrate (5 mM) increased the rate of lipolysis approximately 2–3-fold. Aminobutyric acid and acetate had little or no effect on lipolysis, however propionate stimulated lipolysis, suggesting that butyrate and propionate act through their shared activity as histone deacetylase (HDAC) inhibitors. Consistent with this, the HDAC inhibitor trichostatin A (1 µM) also stimulated lipolysis to a similar extent as did butyrate. Western blot data suggested that neither mitogen-activated protein kinase (MAPK) activation nor perilipin down-regulation are necessary for SCFA-induced lipolysis. Stimulation of lipolysis with butyrate and trichostatin A was glucose-dependent. Changes in AMP-activated protein kinase (AMPK) phosphorylation mediated by glucose were independent of changes in rates of lipolysis. The glycolytic inhibitor iodoacetate prevented both butyrate- and tumor necrosis factor-alpha-(TNF-α) mediated increases in rates of lipolysis indicating glucose metabolism is required. However, unlike TNF-α– , butyrate-stimulated lipolysis was not associated with increased lactate release or inhibited by activation of pyruvate dehydrogenase (PDH) with dichloroacetate. These data demonstrate an important relationship between lipolytic activity and reported HDAC inhibitory activity of butyrate, other short-chain fatty acids and trichostatin A. Given that HDAC inhibitors are presently being evaluated for the treatment of diabetes and other disorders, more work will be essential to determine if these effects on lipolysis are due to inhibition of HDAC.
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Affiliation(s)
- John M Rumberger
- Bassett Healthcare , Cooperstown, NY , USA ; Clore Laboratory, University of Buckingham , Buckingham , UK
| | | | - Allan Green
- Department of Chemistry and Biochemistry, SUNY Oneonta , Oneonta, NY , USA
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Abstract
The prevalence of patients with concomitant diabetes mellitus (DM) and heart failure (HF) is growing exponentially. Patients with HF and DM show specific metabolic, neurohormonal, and structural heart abnormalities, which potentially contribute to worse HF outcomes than seen in patients without comorbid DM. Subgroup analysis of recent trials suggest that patients with HF and DM may respond differently to standard therapy, and data are emerging on the possible increase in the risk of hospitalizations for HF in patients with DM treated with specific class of antidiabetic agents, pointing to the need of developing specific medications to be tested in dedicated future studies to address the unique metabolic and hemodynamic alterations seen in these patients.
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20
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Abstract
GLUT4 constitutively recycles between the plasma membrane and intracellular depots. Insulin shifts this dynamic equilibrium towards the plasma membrane by recruiting GLUT4 to the plasma membrane from insulin-responsive vesicles. Muscle is the primary site for dietary glucose deposition; however, how GLUT4 sorts into insulin-responsive vesicles, and if and how insulin resistance affects this process, is unknown. In L6 myoblasts stably expressing myc-tagged GLUT4, we analyzed the intracellular itinerary of GLUT4 as it internalizes from the cell surface and examined if such sorting is perturbed by C2-ceramide, a lipid metabolite causing insulin resistance. Surface-labeled GLUT4myc that internalized for 30 min accumulated in a Syntaxin-6 (Stx6)- and Stx16-positive perinuclear sub-compartment devoid of furin or internalized transferrin, and displayed insulin-responsive re-exocytosis. C2-ceramide dispersed the Stx6-positive sub-compartment and prevented insulin-responsive re-exocytosis of internalized GLUT4myc, even under conditions not affecting insulin-stimulated signaling towards Akt. Microtubule disruption with nocodazole prevented pre-internalized GLUT4myc from reaching the Stx6-positive perinuclear sub-compartment and from undergoing insulin-responsive exocytosis. Removing nocodazole allowed both parameters to recover, suggesting that the Stx6-positive perinuclear sub-compartment was required for GLUT4 insulin-responsiveness. Accordingly, Stx6 knockdown inhibited by ∼50% the ability of internalized GLUT4myc to undergo insulin-responsive re-exocytosis without altering its overall perinuclear accumulation. We propose that Stx6 defines the insulin-responsive compartment in muscle cells. Our data are consistent with a model where ceramide could cause insulin resistance by altering intracellular GLUT4 sorting.
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Affiliation(s)
- Kevin P Foley
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Amira Klip
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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Jadhav KS, Dungan CM, Williamson DL. Metformin limits ceramide-induced senescence in C2C12 myoblasts. Mech Ageing Dev 2013; 134:548-59. [PMID: 24269881 DOI: 10.1016/j.mad.2013.11.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/26/2013] [Accepted: 11/11/2013] [Indexed: 12/14/2022]
Abstract
UNLABELLED High lipid and ceramide concentrations are hallmarks of obese and/or insulin resistant skeletal muscle, yet little is known about its role on cell cycle and senescence. The purpose of this study was to examine the role of ceramide on muscle senescence, and whether metformin limited this response. METHODS Low passage, proliferating C2C12 myoblasts were treated with a control, 50μM C2-ceramide (8h), and/or 2mM metformin, then examined for insulin sensitivity, cell senescence, cell proliferation, cell cycle, protein expression of cell cycle regulators. RESULTS Ceramide treatment caused a dephosphorylation (p<0.05) of Akt and 4E-BP1, regardless of the presence of insulin. The ceramide treated myoblasts displayed higher β-galactosidase staining (p<0.05), reduced BrDu incorporation and total number of cells (p<0.05), and an increased proportion of cells in G2-phase (p<0.05) versus control cultures. Ceramide treatment also upregulated (p<0.05) p53 and p21 protein expression, that was reversed by either pifithrin-α or shRNA for p53. Metformin limited (p<0.05) ceramide's effects on insulin signaling, senescence, and cell cycle regulation. CONCLUSIONS High ceramide concentrations reduced myoblast proliferation that was associated with aberrant cell cycle regulation and a senescent phenotype, which could provide an understanding of skeletal muscle cell adaptation during conditions of high intramuscular lipid deposition and/or obesity.
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Affiliation(s)
- Kavita S Jadhav
- Department of Exercise and Nutrition Sciences, University at Buffalo SUNY, Buffalo, NY 14214, USA
| | - Cory M Dungan
- Department of Exercise and Nutrition Sciences, University at Buffalo SUNY, Buffalo, NY 14214, USA
| | - David L Williamson
- Department of Exercise and Nutrition Sciences, University at Buffalo SUNY, Buffalo, NY 14214, USA.
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Galadari S, Rahman A, Pallichankandy S, Galadari A, Thayyullathil F. Role of ceramide in diabetes mellitus: evidence and mechanisms. Lipids Health Dis 2013; 12:98. [PMID: 23835113 DOI: 10.1186/1476-511X-12-98] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/28/2013] [Indexed: 02/06/2023] Open
Abstract
Diabetes mellitus is a metabolic disease with multiple complications that causes serious diseases over the years. The condition leads to severe economic consequences and is reaching pandemic level globally. Much research is being carried out to address this disease and its underlying molecular mechanism. This review focuses on the diverse role and mechanism of ceramide, a prime sphingolipid signaling molecule, in the pathogenesis of type 1 and type 2 diabetes and its complications. Studies using cultured cells, animal models, and human subjects demonstrate that ceramide is a key player in the induction of β-cell apoptosis, insulin resistance, and reduction of insulin gene expression. Ceramide induces β-cell apoptosis by multiple mechanisms namely; activation of extrinsic apoptotic pathway, increasing cytochrome c release, free radical generation, induction of endoplasmic reticulum stress and inhibition of Akt. Ceramide also modulates many of the insulin signaling intermediates such as insulin receptor substrate, Akt, Glut-4, and it causes insulin resistance. Ceramide reduces the synthesis of insulin hormone by attenuation of insulin gene expression. Better understanding of this area will increase our understanding of the contribution of ceramide to the pathogenesis of diabetes, and further help in identifying potential therapeutic targets for the management of diabetes mellitus and its complications.
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Díaz-Delfín J, Hondares E, Iglesias R, Giralt M, Caelles C, Villarroya F. TNF-α represses β-Klotho expression and impairs FGF21 action in adipose cells: involvement of JNK1 in the FGF21 pathway. Endocrinology 2012; 153:4238-45. [PMID: 22778214 DOI: 10.1210/en.2012-1193] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Fibroblast growth factor 21 (FGF21) is a member of the FGF family that reduces glycemia and ameliorates insulin resistance. Adipose tissue is a main target of FGF21 action. Obesity is associated with a chronic proinflammatory state. Here, we analyzed the role of proinflammatory signals in the FGF21 pathway in adipocytes, evaluating the effects of TNF-α on β-Klotho and FGF receptor-1 expression and FGF21 action in adipocytes. We also determined the effects of rosiglitazone on β-Klotho and FGF receptor-1 expression in models of proinflammatory signal induction in vitro and in vivo (high-fat diet-induced obesity). Because c-Jun NH(2)-terminal kinase 1 (JNK1) serves as a sensing juncture for inflammatory status, we also evaluated the involvement of JNK1 in the FGF21 pathway. TNF-α repressed β-Klotho expression and impaired FGF21 action in adipocytes. Rosiglitazone prevented the reduction in β-Klotho expression elicited by TNF-α. Moreover, β-Klotho levels were reduced in adipose tissue from high-fat diet-induced obese mice, whereas rosiglitazone restored β-Klotho to near-normal levels. β-Klotho expression was increased in white fat from JNK1(-/-) mice. The absence of JNK1 increased the responsiveness of mouse embryonic fibroblast-derived adipocytes and brown adipocytes to FGF21. In conclusion, we show that proinflammatory signaling impairs β-Klotho expression and FGF21 responsiveness in adipocytes. We also show that JNK1 activity is involved in modulating FGF21 effects in adipocytes. The impairment in the FGF21 response machinery in adipocytes and the reduction in FGF21 action in response to proinflammatory signals may play important roles in metabolic alterations in obesity and other diseases associated with enhanced inflammation.
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Affiliation(s)
- Julieta Díaz-Delfín
- Department of Biochemistry and Molecular Biology, University of Barcelona, Avda Diagonal 643, 08028-Barcelona, Spain.
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Abstract
The recent implementation of genomic and lipidomic approaches has produced a large body of evidence implicating the sphingolipid ceramide in a diverse range of physiological processes and as a critical modulator of cellular stress. In this review, we discuss from a historical perspective the most important discoveries produced over the last decade supporting a role for ceramide and its metabolites in the pathogenesis of insulin resistance and other obesity-associated metabolic diseases. Moreover, we describe how a ceramide-centric view of insulin resistance might be reconciled in the context of other prominent models of nutrient-induced insulin resistance.
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Affiliation(s)
- Jose A Chavez
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, NC 27704, USA.
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Li Z, Zhang H, Liu J, Liang CP, Li Y, Li Y, Teitelman G, Beyer T, Bui HH, Peake DA, Zhang Y, Sanders PE, Kuo MS, Park TS, Cao G, Jiang XC. Reducing plasma membrane sphingomyelin increases insulin sensitivity. Mol Cell Biol. 2011;31:4205-4218. [PMID: 21844222 DOI: 10.1128/mcb.05893-11] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
It has been shown that inhibition of de novo sphingolipid synthesis increases insulin sensitivity. For further exploration of the mechanism involved, we utilized two models: heterozygous serine palmitoyltransferase (SPT) subunit 2 (Sptlc2) gene knockout mice and sphingomyelin synthase 2 (Sms2) gene knockout mice. SPT is the key enzyme in sphingolipid biosynthesis, and Sptlc2 is one of its subunits. Homozygous Sptlc2-deficient mice are embryonic lethal. However, heterozygous Sptlc2-deficient mice that were viable and without major developmental defects demonstrated decreased ceramide and sphingomyelin levels in the cell plasma membranes, as well as heightened sensitivity to insulin. Moreover, these mutant mice were protected from high-fat diet-induced obesity and insulin resistance. SMS is the last enzyme for sphingomyelin biosynthesis, and SMS2 is one of its isoforms. Sms2 deficiency increased cell membrane ceramide but decreased SM levels. Sms2 deficiency also increased insulin sensitivity and ameliorated high-fat diet-induced obesity. We have concluded that Sptlc2 heterozygous deficiency- or Sms2 deficiency-mediated reduction of SM in the plasma membranes leads to an improvement in tissue and whole-body insulin sensitivity.
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Ivanova M, Janega P, Matejikova J, Simoncikova P, Pancza D, Ravingerova T, Barancik M. Activation of Akt kinase accompanies increased cardiac resistance to ischemia/reperfusion in rats after short-term feeding with lard-based high-fat diet and increased sucrose intake. Nutr Res 2011; 31:631-43. [DOI: 10.1016/j.nutres.2011.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 07/19/2011] [Accepted: 08/03/2011] [Indexed: 11/25/2022]
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Chun L, Junlin Z, Aimin W, Niansheng L, Benmei C, Minxiang L. Inhibition of ceramide synthesis reverses endothelial dysfunction and atherosclerosis in streptozotocin-induced diabetic rats. Diabetes Res Clin Pract 2011; 93:77-85. [PMID: 21492950 DOI: 10.1016/j.diabres.2011.03.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Revised: 02/17/2011] [Accepted: 03/14/2011] [Indexed: 11/15/2022]
Abstract
OBJECTIVES To explore the effect of myriocin on EDVD and atherosclerosis in diabetic rats. METHODS Rats were fed with a high-fat/high-sucrose/high-cholesterol diet (20% sucrose, 10% animal oil, 1.0% bile salt and 2.5% cholesterol) (hereinafter defined as diabetic groups) or Purina Rodent Chow (NC group), the former was intervened with low dose streptozotocin (30 mg/kg) after feeding 1 month to make diabetic model. The NC group was intervened with citrate buffer and the diabetic rats were intervened with myriocin (0.3 mg/kg Qod) (MTD group) or just solvent (DC group) for 14 weeks. The EDVD, thickness of fatty deposition under endothelium, ceramide, PI3K/PKB/eNOS, NO and other vital parameters were measured after the rats sacrificed. RESULTS In DC group, the ceramide contents in serum and aorta increased, the EDVD was impaired, the fatty deposition under endothelium increased, and the phosphorylation of PI3K/PKB/eNOS and NO release decreased all compared with the NC group (P<0.05). Compared with the DC group, the ceramide contents in MTD group decreased, the EDVD ameliorated, the fatty deposition diminished, and PI3K/PKB/eNOS phosphorylation and NO release (P<0.05) increased. CONCLUSIONS After treated with myriocin, the EDVD in diabetic rats has been improved by increasing PI3K/PKB/eNOS phosphorylation and NO release, and meanwhile the atherosclerosis has reversed.
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MESH Headings
- Animals
- Atherosclerosis/blood
- Atherosclerosis/drug therapy
- Atherosclerosis/metabolism
- Blotting, Western
- Ceramides/blood
- Ceramides/metabolism
- Chromatography, Liquid
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/metabolism
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/pathology
- Endothelium, Vascular/ultrastructure
- Fatty Acids, Monounsaturated/therapeutic use
- Immunohistochemistry
- Male
- Mass Spectrometry
- Microscopy, Electron, Transmission
- Nitric Oxide/blood
- Rats
- Rats, Sprague-Dawley
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Affiliation(s)
- Li Chun
- Department of Endocrinology, Xiangya Hospital of Central South University, Hunan Province, Xiangya Street 78, Changsha 410008, China
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28
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Thrush AB, Harasim E, Chabowski A, Gulli R, Stefanyk L, Dyck DJ. A single prior bout of exercise protects against palmitate-induced insulin resistance despite an increase in total ceramide content. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1200-8. [PMID: 21325642 DOI: 10.1152/ajpregu.00091.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Ceramide accumulation has been implicated in the impairment of insulin-stimulated glucose transport in skeletal muscle following saturated fatty acid (FA) exposure. Importantly, a single bout of exercise can protect against acute lipid-induced insulin resistance. The mechanism by which exercise protects against lipid-induced insulin resistance is not completely known but may occur through a redirection of FA toward triacylglycerol (TAG) and away from ceramide and diacylglycerol (DAG). Therefore, in the current study, an in vitro preparation was used to examine whether a prior bout of exercise could confer protection against palmitate-induced insulin resistance and whether the pharmacological [50 μM fumonisin B(1) (FB1)] inhibition of ceramide synthesis in the presence of palmitate could mimic the protective effect of exercise. Soleus muscle of sedentary (SED), exercised (EX), and SED in the presence of FB1 (SED+FB1) were incubated with or without 2 mM palmitate for 4 h. This 2-mM palmitate exposure impaired insulin-stimulated glucose transport (-28%, P < 0.01) and significantly increased ceramide, DAG, and TAG accumulation in the SED group (P < 0.05). A single prior bout of exercise prevented the detrimental effects of palmitate on insulin signaling and caused a partial redistribution of FA toward TAG (P < 0.05). However, the net increase in ceramide content in response to palmitate exposure in the EX group was not different compared with SED, despite the maintenance of insulin sensitivity. The incubation of soleus from SED rats with FB1 (SED+FB1) prevented the detrimental effects of palmitate and caused a redirection of FA toward TAG accumulation (P < 0.05). Therefore, this research suggests that although inhibiting ceramide accumulation can prevent the detrimental effects of palmitate, a single prior bout of exercise appears to protect against palmitate-induced insulin resistance, which may be independent of changes in ceramide content.
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Affiliation(s)
- A Brianne Thrush
- Dept. of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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29
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Brindley DN, Kok BPC, Kienesberger PC, Lehner R, Dyck JRB. Shedding light on the enigma of myocardial lipotoxicity: the involvement of known and putative regulators of fatty acid storage and mobilization. Am J Physiol Endocrinol Metab 2010; 298:E897-908. [PMID: 20103741 DOI: 10.1152/ajpendo.00509.2009] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Excessive fatty acid (FA) uptake by cardiac myocytes is often associated with adverse changes in cardiac function. This is especially evident in diabetic individuals, where increased intramyocardial triacylglycerol (TG) resulting from the exposure to high levels of circulating FA has been proposed to be a major contributor to diabetic cardiomyopathy. At present, our knowledge of how the heart regulates FA storage in TG and the hydrolysis of this TG is limited. This review concentrates on what is known about TG turnover within the heart and how this is likely to be regulated by extrapolating results from other tissues. We also assess the evidence as to whether increased TG accumulation protects against FA-induced lipotoxicity through limiting the accumulations of ceramides and diacylglycerols versus whether it is a maladaptive response that contributes to cardiac dysfunction.
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Affiliation(s)
- David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
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30
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Bergman BC, Perreault L, Hunerdosse DM, Koehler MC, Samek AM, Eckel RH. Increased intramuscular lipid synthesis and low saturation relate to insulin sensitivity in endurance-trained athletes. J Appl Physiol (1985) 2010; 108:1134-41. [PMID: 20299618 DOI: 10.1152/japplphysiol.00684.2009] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Intramuscular triglyceride (IMTG) has received considerable attention as a potential mechanism promoting insulin resistance. Endurance-trained athletes have high amounts of IMTG but are insulin sensitive, suggesting IMTG content alone does not change insulin action. Recent data suggest increased muscle lipid synthesis protects against fat-induced insulin resistance. We hypothesized that rates of IMTG synthesis at rest would be increased in athletes compared with controls. Eleven sedentary men and 11 endurance-trained male cyclists participated in this study. An intravenous glucose tolerance test was performed to assess insulin action. After 3 days of dietary control and an overnight fast, [13C16]palmitate was infused at 0.0174 micromol.kg(-1).min(-1) for 4 h, followed by a muscle biopsy to measure isotope incorporation into IMTG and diacylglycerol. Compared with controls, athletes were twice as insulin sensitive (P=0.004) and had a significantly greater resting IMTG concentration (athletes: 20.4+/-1.6 microg IMTG/mg dry wt, controls: 14.5+/-1.8 microg IMTG/mg dry wt, P=0.04) and IMTG fractional synthesis rate (athletes: 1.56+/-0.37%/h, controls: 0.61+/-0.15%/h, P=0.03). Stearoyl-CoA desaturase 1 mRNA expression (P=0.02) and protein content (P=0.03) were also significantly greater in athletes. Diacylglycerol, but not IMTG, saturation was significantly less in athletes compared with controls (P=0.002). These data indicate endurance-trained athletes have increased synthesis rates of skeletal muscle IMTG and decreased saturation of skeletal muscle diacylglycerol. Increased synthesis rates are not due to recovery from exercise and are likely adaptations to chronic endurance exercise training.
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Affiliation(s)
- Bryan C Bergman
- Division of Endocrinology, Diabetes, and Metabolism, University of Colorado Denver School of Medicine, PO Box 6511, MS 8106, Aurora, CO 80045, USA.
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31
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Thrush AB, Brindley DN, Chabowski A, Heigenhauser GJ, Dyck DJ. Skeletal muscle lipogenic protein expression is not different between lean and obese individuals: a potential factor in ceramide accumulation. J Clin Endocrinol Metab 2009; 94:5053-61. [PMID: 19837942 DOI: 10.1210/jc.2008-2565] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Skeletal muscle lipid content is increased in obesity. Recent evidence suggests that fatty acid (FA) storage as triacylglycerol (TAG) represents a metabolically safe pool compared to the more bioactive diacylglycerol (DAG) and ceramide. OBJECTIVE/DESIGN The purpose of this study was to compare the expression of lipogenic proteins and ceramide and DAG content in skeletal muscle of lean and obese humans. We hypothesized that lipogenic protein expression would be increased in obese to facilitate the storage of excess FA as TAG. PARTICIPANTS Eighteen lean (BMI < or = 26 kg/m(2)) and 15 obese (BMI > 29 kg/m(2)) women participated in this study. RESULTS There was no difference in the expression of any lipogenic (stearoyl-CoA desaturase-1, stearoyl retinol binding protein-1c, mitochondrial glycerol-3-phosphate acyltransferase, diacylglycerol acyltransferase-1) or sphingolipid proteins measured between lean and obese humans. Total ceramide was increased in muscle from obese humans (lean vs. obese, 529.4 +/- 54.8 vs. 672.4 +/- 57.4 nmol/g; P < 0.05), but there was no difference in total DAG content (lean vs. obese, 2244.1 +/- 278.2 vs. 1941.4 +/- 165.0 nmol/g). Content of protein phosphatase 2A, a ceramide target, was increased in muscle of obese humans (P < 0.05). CONCLUSIONS We propose that in muscle of obese humans there is an insufficient lipogenic response to the lipid oversupply, allowing more FA to be stored as reactive lipid species, particularly ceramide, potentially contributing to subsequent metabolic complications.
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Affiliation(s)
- A Brianne Thrush
- Department of Human Health and Nutritional Sciences, Animal Science and Nutrition Building, Room 203, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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32
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Fernández-Veledo S, Vila-Bedmar R, Nieto-Vazquez I, Lorenzo M. c-Jun N-terminal kinase 1/2 activation by tumor necrosis factor-alpha induces insulin resistance in human visceral but not subcutaneous adipocytes: reversal by liver X receptor agonists. J Clin Endocrinol Metab 2009; 94:3583-93. [PMID: 19567513 DOI: 10.1210/jc.2009-0558] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
AIMS Obesity is associated with a chronic systemic low-grade inflammatory state. Markers of inflammation such as TNF-alpha are linked with increased risk for insulin resistance and type 2 diabetes. The objective of the present study was to dissect the molecular mechanisms that may regulate TNF-alpha-induced insulin resistance in human adipose tissue. METHODS We analyzed the impact of TNF-alpha on glucose uptake and insulin action in human visceral and sc adipocytes. The contribution of different intracellular signaling pathways on metabolic effects of TNF-alpha and the reversal of some of these effects with nuclear receptor agonists were also studied. RESULTS TNF-alpha per se increased glucose transporter-4 translocation to the plasma membrane and glucose uptake by activating the AMP-activated protein kinase/AS160 pathway in both visceral and sc adipocytes. Nevertheless, this cytokine induced an insulin-resistant state in visceral adipocytes by impairing insulin-stimulated glucose uptake and insulin signaling at the insulin receptor substrate (IRS)-1/AKT level. Activation of c-Jun N-terminal kinase (JNK) 1/2 seems to be involved in TNF-alpha-induced insulin resistance, causing phosphorylation of IRS1 at the Ser312 residue. Accordingly, silencing JNK1/2 with either small interfering RNA or chemical inhibitors impaired serine phosphorylation of IRS1, restored downstream insulin signaling, and normalized insulin-induced glucose uptake in the presence of TNF-alpha. Furthermore, TNF-alpha increased the secretion of other proinflammatory cytokines such as IL-6. Pharmacological treatment of adipocytes with liver X receptor agonists reestablished insulin sensitivity by impairing TNF-alpha induction of JNK1/2, phosphorylation of IRS1 (Ser312), and stabilizing IL-6 secretion. CONCLUSIONS TNF-alpha induces insulin resistance on glucose uptake in human visceral but not sc adipocytes, suggesting depot-specific effects of TNF-alpha on glucose uptake. Activation of JNK1/2 appears to be involved in serine phosphorylation of IRS1 and subsequently insulin resistance on glucose uptake, a state that can be reversed by liver X receptor agonists.
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Affiliation(s)
- Sonia Fernández-Veledo
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, Complutense University, 28040, Madrid, Spain.
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33
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Abstract
Previous reports suggest that parathyroid hormone (PTH) is associated with insulin resistance. This research investigated the effects of PTH on insulin signaling in differentiated 3T3-L1 adipocytes. PTH (10 nM, 24 h) treatment induced a reduction in insulin-stimulated glucose uptake, AKT activity (phosphorylated AKT/total AKT protein expression) and a decrease in GLUT4 and IRS-1 protein expression compared to vehicle treated controls in differentiated adipocytes. PTH treatment also induced increased phosphorylation of IRS-1 on serine 307, which suppresses insulin signaling. In addition, treatment of cells with adenyl cyclase inhibitor SQ52236 ameliorated the effects of PTH on insulin-stimulated glucose uptake, whereas inhibition of phospholipase C alpha (U73122) did not significantly alter the effects of PTH. Thus, PTH treatment of differentiated 3T3-L1 adipocytes suppresses insulin-stimulated glucose uptake and insulin signaling via cAMP pathway, potentially through the phosphorylation of IRS-1 at serine 307.
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Affiliation(s)
| | | | - Dorothy Teegarden
- Corresponding Author: Dorothy Teegarden, PhD, 700 W. State St., West Lafayette IN 47907, 765-494-8246, FAX: 765-494-0906,
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Kachko I, Maissel A, Mazor L, Ben-Romano R, Watson RT, Hou JC, Pessin JE, Bashan N, Rudich A. Postreceptoral adipocyte insulin resistance induced by nelfinavir is caused by insensitivity of PKB/Akt to phosphatidylinositol-3,4,5-trisphosphate. Endocrinology 2009; 150:2618-26. [PMID: 19179444 PMCID: PMC2689810 DOI: 10.1210/en.2008-1205] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Adipocyte insulin resistance can be caused by proximal insulin signaling defects but also from postreceptor mechanisms, which in large are poorly characterized. Adipocytes exposed for 18 h to the HIV protease inhibitor nelfinavir manifest insulin resistance characterized by normal insulin-stimulated tyrosine phosphorylation of the insulin receptor and insulin receptor substrate proteins, preserved in vitro phosphatidylinositol 3-kinase (PI 3-kinase) assay activity but impaired activation of PKB/Akt and stimulation of glucose uptake. Here we aimed to assess whether impaired PKB/Akt activation is indeed rate limiting for insulin signaling propagation in response to nelfinavir and the mechanism for defective PKB/Akt activation. Nelfinavir treatment of 3T3-L1 adipocytes impaired the insulin-stimulated translocation and membrane fusion of myc-glucose transporter (GLUT)-4-green fluorescent protein (GFP) reporter. Phosphorylation of PKB/Akt substrates including glycogen synthase kinase-3 and AS160 decreased in response to nelfinavir, and this remained true, even in cells with forced generation of phosphatidylinositol-3,4,5-trisphohphate (PIP(3)) by a membrane-targeted active PI 3-kinase, confirming that impaired PKB/Akt activation was rate limiting for insulin signal propagation. Cells expressing a GFP-tagged pleckstrin homology domain of general receptors for phosphoinositides 1, which binds PIP(3), revealed intact PIP(3)-mediated plasma membrane translocation of this reporter in nelfinavir-treated cells. However, expression of a membrane-targeted catalytic subunit of PI 3-kinase failed to induce myc-GLUT4-GFP translocation in the absence of insulin, as it did in control cells. Conversely, a membrane-targeted and constitutively active PKB/Akt mutant was normally phosphorylated on S473 and T308, confirming intact PKB/Akt kinases activity, and induced myc-GLUT4-GFP translocation. Collectively, nelfinavir uncovers a postreceptor mechanism for insulin resistance, caused by interference with the sensing of PIP(3) by PKB/Akt, leading to impaired GLUT4 translocation and membrane fusion.
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Affiliation(s)
- Ilana Kachko
- Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, Israel
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35
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Bashan N, Kovsan J, Kachko I, Ovadia H, Rudich A. Positive and negative regulation of insulin signaling by reactive oxygen and nitrogen species. Physiol Rev 2009; 89:27-71. [PMID: 19126754 DOI: 10.1152/physrev.00014.2008] [Citation(s) in RCA: 351] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Regulated production of reactive oxygen species (ROS)/reactive nitrogen species (RNS) adequately balanced by antioxidant systems is a prerequisite for the participation of these active substances in physiological processes, including insulin action. Yet, increasing evidence implicates ROS and RNS as negative regulators of insulin signaling, rendering them putative mediators in the development of insulin resistance, a common endocrine abnormality that accompanies obesity and is a risk factor of type 2 diabetes. This review deals with this dual, seemingly contradictory, function of ROS and RNS in regulating insulin action: the major processes for ROS and RNS generation and detoxification are presented, and a critical review of the evidence that they participate in the positive and negative regulation of insulin action is provided. The cellular and molecular mechanisms by which ROS and RNS are thought to participate in normal insulin action and in the induction of insulin resistance are then described. Finally, we explore the potential usefulness and the challenges in modulating the oxidant-antioxidant balance as a potentially promising, but currently disappointing, means of improving insulin action in insulin resistance-associated conditions, leading causes of human morbidity and mortality of our era.
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Affiliation(s)
- Nava Bashan
- Department of Clinical Biochemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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36
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Abstract
Insulin resistance is an important risk factor for type 2 diabetes, obesity, cardiovascular disease, polycystic ovary syndrome and other diseases. The most important stage in the development of insulin resistance is impairment of insulin-stimulated skeletal muscle glucose uptake. There is evidence that intramyocellular lipids might be responsible for this process through inhibition of insulin signaling. One of the important intracellular lipid pools is associated with the sphingomyelin signaling pathway. The second messenger in this pathway is ceramide. In vitro data indicate that ceramide inhibits insulin signaling, mainly through inactivation of protein kinase B. In vivo data suggest that ceramide accumulation within muscle cells might be associated with the development of insulin resistance. In this review, we discuss both in vitro and in vivo evidence for the role of muscle ceramide in the impairment of insulin action with particular focus on the question whether findings from animal studies are applicable to humans. We describe problems that are unresolved so far and topics of potential interest for future research.
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Affiliation(s)
- Marek Straczkowski
- Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Bialystok, Poland
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37
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Arboleda G, Huang TJ, Waters C, Verkhratsky A, Fernyhough P, Gibson RM. Insulin-like growth factor-1-dependent maintenance of neuronal metabolism through the phosphatidylinositol 3-kinase-Akt pathway is inhibited by C2-ceramide in CAD cells. Eur J Neurosci 2007; 25:3030-8. [PMID: 17561816 DOI: 10.1111/j.1460-9568.2007.05557.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Ceramide is a lipid second-messenger generated in response to stimuli associated with neurodegeneration that induces apoptosis, a mechanism underlying neuronal death in Parkinson's disease. We tested the hypothesis that insulin-like growth factor-1 (IGF-1) could mediate a metabolic response in CAD cells, a dopaminergic cell line of mesencephalic origin that differentiate into a neuronal-like phenotype upon serum removal, extend processes resembling neurites, synthesize abundant dopamine and noradrenaline and express the catecholaminergic biosynthetic enzymes tyrosine hydroxylase and dopamine beta-hydroxylase, and that this process was phosphatidylinositol 3-kinase (PI 3-K)-Akt-dependent and could be inhibited by C(2)-ceramide. The metabolic response was evaluated as real-time changes in extracellular acidification rate (ECAR) using microphysiometry. The IGF-1-induced ECAR response was associated with increased glycolysis, determined by increased NAD(P)H reduction, elevated hexokinase activity and Akt phosphorylation. C(2)-ceramide inhibited all these changes in a dose-dependent manner, and was specific, as it was not induced by the inactive C(2)-ceramide analogue C(2)-dihydroceramide. Inhibition of the upstream kinase, PI 3-K, also inhibited Akt phosphorylation and the metabolic response to IGF-1, similar to C(2)-ceramide. Decreased mitochondrial membrane potential occurred after loss of Akt phosphorylation. These results show that IGF-1 can rapidly modulate neuronal metabolism through PI 3-K-Akt and that early metabolic inhibition induced by C(2)-ceramide involves blockade of the PI 3-K-Akt pathway, and may compromise the first step of glycolysis. This may represent a new early event in the C(2)-ceramide-induced cell death pathway that could coordinate subsequent changes in mitochondria and commitment of neurons to apoptosis.
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Affiliation(s)
- Gonzalo Arboleda
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK.
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38
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Benson C, Seger M, Voelker J. Inhibition of PKC β by Ruboxistaurin Does Not Enhance the Acute Blood Pressure Response to Nitroglycerin. Clin Pharmacol Ther 2007; 82:181-6. [PMID: 17443133 DOI: 10.1038/sj.clpt.6100210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ruboxistaurin is a selective protein kinase C beta inhibitor undergoing clinical investigation for treatment of diabetic microvascular complications. This study assessed a possible blood pressure (BP) interaction between ruboxistaurin and the exogenous nitric oxide donor, glyceryl trinitrate (GTN). Subjects (N=22) with chronic stable angina received placebo or ruboxistaurin 96 mg/day orally to steady state in a crossover design. Graded GTN (0, 5, 10, 20, 40, 80, and 120 microg/min) or 5% dextrose solution was then infused intravenously and BP was measured following each dose. Ruboxistaurin did not alter the slope of change in standing systolic BP (DeltasSBP/1n[GTN dose]) curve (P=0.272 analysis of covariance) or affect the DeltasSBP at the estimated GTN dose producing a 10-mm Hg reduction in sSBP from baseline on placebo (mean difference -0.9 mm Hg; 95% confidence of interval, -3.3-1.5). In conclusion, ruboxistaurin does not potentiate the acute BP-lowering effects of GTN.
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Affiliation(s)
- C Benson
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA
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Pickersgill L, Litherland GJ, Greenberg AS, Walker M, Yeaman SJ. Key role for ceramides in mediating insulin resistance in human muscle cells. J Biol Chem 2007; 282:12583-9. [PMID: 17337731 DOI: 10.1074/jbc.m611157200] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Elevated non-esterified fatty acids, triglyceride, diacylglycerol, and ceramide have all been associated with insulin resistance in muscle. We set out to investigate the role of intramyocellular lipid metabolites in the induction of insulin resistance in human primary myoblast cultures. Muscle cells were subjected to adenovirus-mediated expression of perilipin or incubated with fatty acids for 18 h, prior to insulin stimulation and measurement of lipid metabolites and rates of glycogen synthesis. Adenovirus-driven perilipin expression lead to significant accumulation of triacylglycerol in myoblasts, without any detectable effect on insulin sensitivity, as judged by the ability of insulin to stimulate glycogen synthesis. Similarly, incubation of cells with the monounsaturated fatty acid oleate resulted in triacylglycerol accumulation without inhibiting insulin action. By contrast, the saturated fatty acid palmitate induced insulin resistance. Palmitate treatment caused less accumulation of triacylglycerol than did oleate but also induced significant accumulation of both diacylglycerol and ceramide. Insulin resistance was also caused by cell-permeable analogues of ceramide, and palmitate-induced resistance was blocked in the presence of inhibitors of de novo ceramide synthesis. Oleate co-incubation completely prevented the insulin resistance induced by palmitate. Our data are consistent with ceramide being the agent responsible for insulin resistance caused by palmitate exposure. Furthermore, the triacylglycerol derived from oleate was able to exert a protective role in sequestering palmitate, thus preventing its conversion to ceramide.
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Affiliation(s)
- Laura Pickersgill
- Institute of Cell & Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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40
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [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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41
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Ghosh N, Patel N, Jiang K, Watson JE, Cheng J, Chalfant CE, Cooper DR. Ceramide-activated protein phosphatase involvement in insulin resistance via Akt, serine/arginine-rich protein 40, and ribonucleic acid splicing in L6 skeletal muscle cells. Endocrinology 2007; 148:1359-66. [PMID: 17158207 PMCID: PMC2664306 DOI: 10.1210/en.2006-0750] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Elevated TNFalpha levels are associated with insulin resistance, but the molecular mechanisms linking cytokine signaling to impaired insulin function remain elusive. We previously demonstrated a role for Akt in insulin regulation of protein kinase CbetaII alternative splicing through phosphorylation of serine/arginine-rich protein 40, a required mechanism for insulin-stimulated glucose uptake. We hypothesized that TNFalpha attenuated insulin signaling by dephosphorylating Akt and its targets via ceramide-activated protein phosphatase. Western blot analysis of L6 cell lysates demonstrated impaired insulin-stimulated phosphorylation of Akt, serine/arginine-rich protein 40, and glycogen synthase kinase 3beta in response to TNFalpha and the short chain C6 ceramide analog. TNFalpha increased serine/threonine phosphatase activity of protein phosphatase 1 (PP1) in response to C6, but not insulin, suggesting a ceramide-specific effect. Myriocin, an inhibitor of de novo ceramide synthesis, blocked stimulation of the PP1 activity. Ceramide species measurement by liquid chromatography-mass spectrometry showed consistent increases in C24:1 and C16 ceramides. Effects of TNFalpha and C6 on insulin-stimulated phosphorylation of glycogen synthase kinase 3beta were prevented by myriocin and tautomycin, a PP1 inhibitor, further implicating a de novo ceramide-PP1 pathway. Alternative splicing assays demonstrated that TNFalpha abolished insulin-mediated inclusion of the protein kinase CbetaII exon. Collectively, our work demonstrates a role for PP1-like ceramide-activated protein phosphatase in mediating TNFalpha effects blocking insulin phosphorylation cascades involved in glycogen metabolism and alternative splicing.
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Affiliation(s)
- Nilanjan Ghosh
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612
| | - Niketa Patel
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612
| | - Kun Jiang
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612
| | - James E. Watson
- The Research Service, James A. Haley Veterans Hospital, Tampa, FL 33612
| | - Jin Cheng
- Moffitt Cancer Center, Tampa, FL 33612
| | - Charles E. Chalfant
- Department of Biochemistry, Virginia Commonwealth University, Richmond Virginia 23298
| | - Denise R. Cooper
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612
- The Research Service, James A. Haley Veterans Hospital, Tampa, FL 33612
- Corresponding author: Denise R. Cooper, Ph.D., J.A. Haley Veterans Hospital VAR 151, 13000 Bruce B. Downs Blvd, Tampa, FL 33612, E-mail: , Telephone: 813-972-2000 ext 7017, Fax: 813-972-7623
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Casano-Sancho P, López-Bermejo A, Fernández-Real JM, Monrós E, Valls C, Rodríguez-González FX, Ricart W, Ibáñez L. The tumour necrosis factor (TNF)-alpha-308GA promoter polymorphism is related to prenatal growth and postnatal insulin resistance. Clin Endocrinol (Oxf) 2006; 64:129-35. [PMID: 16430709 DOI: 10.1111/j.1365-2265.2006.02434.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Variation in the tumour necrosis factor gene, (TNF) has been associated with insulin resistance traits. We questioned whether the TNF-308G/A polymorphism is associated with birthweight and insulin resistance in children born small for gestational age (SGA), a patient population known to be at risk for insulin resistance. DESIGN A cross-sectional, hospital-based study assessing insulin sensitivity in SGA children. PATIENTS One hundred and ninety-eight school-age children born either SGA (n=90, age 7.4+/- 4.5 years) or appropriate for gestational age (AGA, n=108, age 8.7+/- 4.0 years). MEASUREMENTS All children were genotyped for the TNF-308G/A polymorphism; a biochemical profile was also performed in prepubertal SGA (n=58) and AGA (n=57) subjects. RESULTS Genotype frequencies for the TNF-308G/A single nucleotide polymorphisms (SNPs) (GG and GA/AA) differed between SGA and AGA children (86%vs. 72% and 14%vs. 28%, respectively; P=0.025). The GG genotype was associated with lower birthweight and birth length (2747.0+/- 23.3 g vs. 2851.0+/- 45.7 g, P=0.045, and 47.0+/- 0.2 cm vs. 48.2+/- 0.4 cm, P=0.011, respectively) and, in AGA but not in SGA children, with higher systolic blood pressure [103.3 (95% confidence interval (CI) 96.4-110.2) mmHg vs. 92.8 (84.9-100.7) mmHg; P=0.028], higher blood glucose [4.8 (4.7-5.0) mmol/l vs. 4.5 (4.3-4.8) mmol/l; P=0.042] and higher homeostasis model assessment for insulin resistance (HOMA-IR) index [1.4 (1.1-1.7) vs. 0.9 (0.4-1.3); P=0.005]. In multivariate analysis, the TNF-308GG genotype was an independent predictor of HOMA-IR during childhood, explaining 8% of its variance. CONCLUSION SGA children show increased frequency of the TNF-308G allele, an allele that is associated with prenatal growth and with postnatal insulin resistance. The TNF-308G/A polymorphism may have implications in the growth and metabolic abnormalities that characterise SGA children.
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Affiliation(s)
- Paula Casano-Sancho
- Paediatric Endocrinology, Sant Joan de Déu Children's Hospital, Barcelona, Spain
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Chavez JA, Holland WL, Bär J, Sandhoff K, Summers SA. Acid ceramidase overexpression prevents the inhibitory effects of saturated fatty acids on insulin signaling. J Biol Chem 2005; 280:20148-53. [PMID: 15774472 DOI: 10.1074/jbc.m412769200] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Recent studies indicate that insulin resistance and type 2 diabetes result from the accumulation of lipids in tissues not suited for fat storage, such as skeletal muscle and the liver. To elucidate the mechanisms linking exogenous fats to the inhibition of insulin action, we evaluated the effects of free fatty acids (FFAs) on insulin signal transduction in cultured C2C12 myotubes. As we described previously (Chavez, J. A., and Summers, S. A. (2003) Arch. Biochem. Biophys. 419, 101-109), long-chain saturated FFAs inhibited insulin stimulation of Akt/protein kinase B, a central regulator of glucose uptake and anabolic metabolism. Moreover, these FFAs stimulated the de novo synthesis of ceramide and sphingosine, two sphingolipids shown previously to inhibit insulin action. To determine the contribution of either sphingolipid in FFA-dependent inhibition of insulin action, we generated C2C12 myotubes that constitutively overexpress acid ceramidase (AC), an enzyme that catalyzes the lysosomal conversion of ceramide to sphingosine. AC overexpression negated the inhibitory effects of saturated FFAs on insulin signaling while blocking their stimulation of ceramide accumulation. By contrast, AC overexpression stimulated the accrual of sphingosine. These results support a role for aberrant accumulation of ceramide, but not sphingosine, in the inhibition of muscle insulin sensitivity by exogenous FFAs.
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Affiliation(s)
- Jose Antonio Chavez
- Department of Internal Medicine, Division of Endocrinology, Metabolism, and Diabetes, University of Utah, Salt Lake City, 84132, USA
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Abstract
Type 2 diabetes mellitus is a complex metabolic disease that occurs when insulin secretion can no longer compensate insulin resistance in peripheral tissues. At the molecular level, insulin resistance correlates with impaired insulin signalling. This review provides new insights into the molecular mechanisms of insulin action and resistance in brown adipose tissue and pinpoints the role of this tissue in the control of glucose homeostasis. Brown adipocytes are target cells for insulin and IGF-I action, especially during late foetal development when insulin supports survival and promotes both adipogenic and thermogenic differentiation. The main pathway involved in insulin induction of adipogenic differentiation, monitored by fatty acid synthase expression, is the cascade insulin receptor substrate (IRS)-1/phosphatidylinositol 3-kinase (PI3K)/Akt. Glucose transport in these cells is maintained mainly by the activity of GLUT4. Acute insulin treatment stimulates glucose transport largely by mediating translocation of GLUT4 to the plasma membrane, involving the activation of IRS-2/PI3K, and the downstream targets Akt and protein kinase C zeta. Tumour necrosis factor (TNF-alpha) caused insulin resistance on glucose uptake by impairing insulin signalling at the level of IRS-2. Activation of stress kinases and phosphatases by this cytokine contribute to insulin resistance. Furthermore, brown adipocytes are also target cells for rosiglitazone action since they show a high expression of peroxisome proliferator activated receptor gamma, and rosiglitazone increased the expression of the thermogenic uncoupling protein 1. Rosiglitazone ameliorates insulin resistance provoked by TNF-alpha, completely restoring insulin-stimulated glucose uptake in parallel to the insulin signalling cascade. Accordingly, foetal brown adipocytes represent a model for investigating insulin action, as well as for the mechanism by which rosiglitazone increase insulin sensitivity under situations that mimic insulin resistance.
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Affiliation(s)
- A M Valverde
- Instituto de Bioquimica. Centro Mixto CSIC/UCM, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain
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Hernandez R, Teruel T, de Alvaro C, Lorenzo M. Rosiglitazone ameliorates insulin resistance in brown adipocytes of Wistar rats by impairing TNF-alpha induction of p38 and p42/p44 mitogen-activated protein kinases. Diabetologia 2004; 47:1615-24. [PMID: 15365619 DOI: 10.1007/s00125-004-1503-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Accepted: 04/22/2004] [Indexed: 01/25/2023]
Abstract
AIMS/HYPOTHESIS TNF-alpha caused insulin resistance on glucose uptake and on insulin signalling in fetal brown adipocytes. Since treatment with TNF-alpha activates stress kinases, including c-jun NH2 terminal kinase (JNK), and p42/p44 and p38 mitogen-activated protein kinases (MAPK), we explored the contribution of these pathways to insulin resistance by TNF-alpha. Rosiglitazone is used to treat Type 2 diabetes as it improves insulin sensitivity in vivo. However, its ability to ameliorate TNF-alpha-induced insulin resistance in brown adipocytes remains to be explored. METHODS We used fetal rat primary brown adipocytes cultured with TNF-alpha, with or without stress kinase inhibitors or rosiglitazone, and further stimulated with insulin. Then, we measured glucose uptake and GLUT4 translocation. To determine the insulin signalling cascade, we submitted cells to lysis, immunoprecipitation and immunoblotting. RESULTS Exposure to TNF-alpha for 24 h impairs insulin stimulation of the phosphatidylinositol (PI) 3-kinase activity associated with IRS-2 and Akt activity. Pretreatment with PD98059 or PD169316, which inhibit p42/p44MAPK and p38MAPK respectively, restored insulin signalling and insulin-induced glucose uptake in the presence of TNF-alpha. However, in the presence of SP600125, an inhibitor of JNK, TNF-alpha still produced insulin resistance. Rosiglitazone ameliorated insulin resistance by TNF-alpha in brown adipocytes, restoring completely insulin-stimulated glucose uptake and insulin-induced GLUT4 translocation to plasma membrane in parallel to the insulin signalling cascade IRS-2/PI 3-kinase/Akt. CONCLUSIONS/INTERPRETATION Rosiglitazone treatment impaired TNF-alpha activation of p38 and p42/p44MAPK, restoring insulin signalling and leading to normalisation of glucose uptake.
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Affiliation(s)
- R Hernandez
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, Complutense University, 28040-Madrid, Spain
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Liu P, Leffler BJ, Weeks LK, Chen G, Bouchard CM, Strawbridge AB, Elmendorf JS. Sphingomyelinase activates GLUT4 translocation via a cholesterol-dependent mechanism. Am J Physiol Cell Physiol 2003; 286:C317-29. [PMID: 14522816 DOI: 10.1152/ajpcell.00073.2003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A basis for the insulin mimetic effect of sphingomyelinase on glucose transporter isoform GLUT4 translocation remains unclear. Because sphingomyelin serves as a major determinant of plasma membrane cholesterol and a relationship between plasma membrane cholesterol and GLUT4 levels has recently become apparent, we assessed whether GLUT4 translocation induced by sphingomyelinase resulted from changes in membrane cholesterol content. Exposure of 3T3-L1 adipocytes to sphingomyelinase resulted in a time-dependent loss of sphingomyelin from the plasma membrane and a concomitant time-dependent accumulation of plasma membrane GLUT4. Degradation products of sphingomyelin did not mimic this stimulatory action. Plasma membrane cholesterol amount was diminished in cells exposed to sphingomyelinase. Restoration of membrane cholesterol blocked the stimulatory effect of sphingomyelinase. Increasing concentrations of methyl-beta-cyclodextrin, which resulted in a dose-dependent reversible decrease in membrane cholesterol, led to a dose-dependent reversible increase in GLUT4 incorporation into the plasma membrane. Although increased plasma membrane GLUT4 content by cholesterol extraction with concentrations of methyl-beta-cyclodextrin above 5 mM most likely reflected decreased GLUT4 endocytosis, translocation stimulated by sphingomyelinase or concentrations of methyl-beta-cyclodextrin below 2.5 mM occurred without any visible changes in the endocytic retrieval of GLUT4. Furthermore, moderate loss of cholesterol induced by sphingomyelinase or low concentrations of methyl-beta-cyclodextrin did not alter membrane integrity or increase the abundance of other plasma membrane proteins such as the GLUT1 glucose transporter or the transferrin receptor. Regulation of GLUT4 translocation by moderate cholesterol loss did not involve known insulin-signaling proteins. These data reveal that sphingomyelinase enhances GLUT4 exocytosis via a novel cholesterol-dependent mechanism.
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Affiliation(s)
- Ping Liu
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Center for Diabetes Research, Indianapolis, IN 46202, USA
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Chavez JA, Knotts TA, Wang LP, Li G, Dobrowsky RT, Florant GL, Summers SA. A role for ceramide, but not diacylglycerol, in the antagonism of insulin signal transduction by saturated fatty acids. J Biol Chem 2003; 278:10297-303. [PMID: 12525490 DOI: 10.1074/jbc.m212307200] [Citation(s) in RCA: 455] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Multiple studies suggest that lipid oversupply to skeletal muscle contributes to the development of insulin resistance, perhaps by promoting the accumulation of lipid metabolites capable of inhibiting signal transduction. Herein we demonstrate that exposing muscle cells to particular saturated free fatty acids (FFAs), but not mono-unsaturated FFAs, inhibits insulin stimulation of Akt/protein kinase B, a serine/threonine kinase that is a central mediator of insulin-stimulated anabolic metabolism. These saturated FFAs concomitantly induced the accumulation of ceramide and diacylglycerol, two products of fatty acyl-CoA that have been shown to accumulate in insulin-resistant tissues and to inhibit early steps in insulin signaling. Preventing de novo ceramide synthesis negated the antagonistic effect of saturated FFAs toward Akt/protein kinase B. Moreover, inducing ceramide buildup recapitulated and augmented the inhibitory effect of saturated FFAs. By contrast, diacylglycerol proved dispensable for these FFA effects. Collectively these results identify ceramide as a necessary and sufficient intermediate linking saturated fats to the inhibition of insulin signaling.
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Affiliation(s)
- Jose Antonio Chavez
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins 80523-1870, USA
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Fujishiro M, Gotoh Y, Katagiri H, Sakoda H, Ogihara T, Anai M, Onishi Y, Ono H, Abe M, Shojima N, Fukushima Y, Kikuchi M, Oka Y, Asano T. Three mitogen-activated protein kinases inhibit insulin signaling by different mechanisms in 3T3-L1 adipocytes. Mol Endocrinol 2003; 17:487-97. [PMID: 12554784 DOI: 10.1210/me.2002-0131] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
TNFalpha, which activates three different MAPKs [ERK, p38, and jun amino terminal kinase (JNK)], also induces insulin resistance. To better understand the respective roles of these three MAPK pathways in insulin signaling and their contribution to insulin resistance, constitutively active MAPK/ERK kinase (MEK)1, MAPK kinase (MKK6), and MKK7 mutants were overexpressed in 3T3-L1 adipocytes using an adenovirus-mediated transfection procedure. The MEK1 mutant, which activates ERK, markedly down-regulated expression of the insulin receptor (IR) and its major substrates, IRS-1 and IRS-2, mRNA and protein, and in turn reduced tyrosine phosphorylation of IR as well as IRS-1 and IRS-2 and their associated phosphatidyl inositol 3-kinase (PI3K) activity. The MKK6 mutant, which activates p38, moderately inhibited IRS-1 and IRS-2 expressions and IRS-1-associated PI3K activity without exerting a significant effect on the IR. Finally, the MKK7 mutant, which activates JNK, reduced tyrosine phosphorylation of IRS-1 and IRS-2 and IRS-associated PI3K activity without affecting expression of the IR, IRS-1, or IRS-2. In the context of our earlier report showing down-regulation of glucose transporter 4 by MEK1-ERK and MKK6/3-p38, the present findings suggest that chronic activation of ERK, p38, or JNK can induce insulin resistance by affecting glucose transporter expression and insulin signaling, though via distinctly different mechanisms. The contribution of ERK is, however, the strongest.
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Affiliation(s)
- Midori Fujishiro
- Department of Diabetes and Metabolism, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan
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Mei J, Wang CN, O'Brien L, Brindley DN. Cell-permeable ceramides increase basal glucose incorporation into triacylglycerols but decrease the stimulation by insulin in 3T3-L1 adipocytes. Int J Obes (Lond) 2003; 27:31-9. [PMID: 12532151 DOI: 10.1038/sj.ijo.0802183] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2002] [Revised: 07/10/2002] [Accepted: 07/16/2002] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To investigate mechanisms for the regulation of glucose incorporation into triacylgycerols in adipocytes by ceramides, which mediate some actions of tumour necrosis factor-alpha (TNFalpha). DESIGN The effects of C(2)- and C(6)-ceramides (N-acetyl- and N-hexanoyl-sphingosines, respectively) on glucose uptake and incorporation into triacylglycerols and pathways of signal tansduction were measured in 3T3-L1 adipocytes. RESULTS C(6)-ceramide increased basal 2-deooxyglucose uptake but decreased insulin-stimulated uptake without changing the EC(50) for insulin. Incubating 3T3-L1 adipocytes from 2 to 24 h with C(2)-ceramide progressively increased glucose incorporation into the fatty acid and especially the glycerol moieties of triacylglycerol. These effects were accompanied by increased GLUT1 synthesis resulting from ceramide-induced activation phosphatidylinositol 3-kinase, ribosomal S6 kinase and mitogen-activated protein kinase. C(2)-ceramide also increased p21-activated kinase and protein kinase B activities. However, C(2)-ceramide decreased the insulin-stimulated component of these signalling pathways and also glucose incorporation into triacylglycerol after 2 h. CONCLUSIONS Cell-permeable ceramides can mimic some effects of TNFalpha in producing insulin resistance. However, ceramides also mediate long-term effects that enable 3T3 L1 adipocytes to take up glucose and store triacylglycerols in the absence of insulin. These observations help to explain part of the nature and consequence of TNFalpha-induced insulin resistance and the control of fat accumulation in adipocytes in insulin resistance and obesity.
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Affiliation(s)
- J Mei
- Department of Biochemistry (Signal Transduction Research Group), University of Alberta, Edmonton, Alberta, Canada
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Miura A, Kajita K, Ishizawa M, Kanoh Y, Kawai Y, Natsume Y, Sakuma H, Yamamoto Y, Yasuda K, Ishizuka T. Inhibitory effect of ceramide on insulin-induced protein kinase Czeta translocation in rat adipocytes. Metabolism 2003; 52:19-24. [PMID: 12524657 DOI: 10.1053/meta.2003.50011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Ceramide has been confirmed to be a signal mediator of apoptosis that is induced by tumor necrosis factor-alpha (TNF-alpha). It has also been reported that ceramide may induce insulin resistance as well as TNF-alpha. We investigated the effect of ceramide on insulin signaling pathways, such as insulin receptor (IR) beta-subunit, insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and protein kinase Czeta (PKCzeta) in rat adipocytes. We examined insulin-stimulated [(3)H]2-deoxyglucose (2-DOG) uptake in rat adipocytes pretreated with N-hexanoylsphingosine (C(6)-ceramide, 10 to 30 micromol/L). Insulin-induced 2-DOG uptake was significantly reduced by C(6)-ceramide pretreatment. We also examined the effect of various concentrations of C(6)-ceramide pretreatment on insulin-induced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, enzyme activity of PI3K, and membrane-associated PKCzeta immunoreactivity. Pretreatment with C(6)-ceramide significantly reduced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, and enzyme activity of PI3K. Moreover, membrane-associated PKCzeta immunoreactivity and immunoprecipitable PKCzeta enzyme activity, downstream of PI3K, were significantly suppressed by C(6)-ceramide pretreatment. These results suggest that ceramide may induce insulin resistance via the suppression of IRS-1-PI3K signaling, and subsequent activation of PKCzeta.
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Affiliation(s)
- Atsushi Miura
- Third Department of Internal Medicine, Gifu University School of Medicine, Gifu, Japan
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