1
|
Veres T, Kerestély M, Kovács BM, Keresztes D, Schulc K, Seitz E, Vassy Z, Veres DV, Csermely P. Cellular forgetting, desensitisation, stress and ageing in signalling networks. When do cells refuse to learn more? Cell Mol Life Sci 2024; 81:97. [PMID: 38372750 PMCID: PMC10876757 DOI: 10.1007/s00018-024-05112-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/09/2023] [Accepted: 01/02/2024] [Indexed: 02/20/2024]
Abstract
Recent findings show that single, non-neuronal cells are also able to learn signalling responses developing cellular memory. In cellular learning nodes of signalling networks strengthen their interactions e.g. by the conformational memory of intrinsically disordered proteins, protein translocation, miRNAs, lncRNAs, chromatin memory and signalling cascades. This can be described by a generalized, unicellular Hebbian learning process, where those signalling connections, which participate in learning, become stronger. Here we review those scenarios, where cellular signalling is not only repeated in a few times (when learning occurs), but becomes too frequent, too large, or too complex and overloads the cell. This leads to desensitisation of signalling networks by decoupling signalling components, receptor internalization, and consequent downregulation. These molecular processes are examples of anti-Hebbian learning and 'forgetting' of signalling networks. Stress can be perceived as signalling overload inducing the desensitisation of signalling pathways. Ageing occurs by the summative effects of cumulative stress downregulating signalling. We propose that cellular learning desensitisation, stress and ageing may be placed along the same axis of more and more intensive (prolonged or repeated) signalling. We discuss how cells might discriminate between repeated and unexpected signals, and highlight the Hebbian and anti-Hebbian mechanisms behind the fold-change detection in the NF-κB signalling pathway. We list drug design methods using Hebbian learning (such as chemically-induced proximity) and clinical treatment modalities inducing (cancer, drug allergies) desensitisation or avoiding drug-induced desensitisation. A better discrimination between cellular learning, desensitisation and stress may open novel directions in drug design, e.g. helping to overcome drug resistance.
Collapse
Affiliation(s)
- Tamás Veres
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Márk Kerestély
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Borbála M Kovács
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Dávid Keresztes
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Klára Schulc
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
- Division of Oncology, Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
| | - Erik Seitz
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Zsolt Vassy
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
| | - Dániel V Veres
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary
- Turbine Ltd, Budapest, Hungary
| | - Peter Csermely
- Department of Molecular Biology, Semmelweis University, Budapest, Hungary.
| |
Collapse
|
2
|
Joseph JJ, Kluwe B, Zhao S, Kline D, Nedungadi D, Brock G, Hsueh WA, Golden SH. The association of aldosterone and endothelin-1 with incident diabetes among African Americans: The Jackson Heart Study. ENDOCRINE AND METABOLIC SCIENCE 2023; 11:100128. [PMID: 37475850 PMCID: PMC10358435 DOI: 10.1016/j.endmts.2023.100128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023] Open
Abstract
Introduction African Americans (AAs) have the highest prevalence of hypertension among United States racial/ethnic groups. Regulators of blood pressure, such as aldosterone and endothelin-1, impact glucose regulation. The relationship between these factors and incident diabetes is not well elucidated among AAs. Methods Among 3914 AA participants without prevalent diabetes in the Jackson Heart Study, linear regression models were used to examine cross-sectional associations of exposures (aldosterone, endothelin-1, and a combined aldosterone-endothelin-1 score [2-8]) with glycemic measures (fasting plasma glucose [FPG], HbA1c, homeostatic model assessments of beta cell function [HOMA-β] and insulin resistance [HOMA-IR]). Longitudinal associations of exposures with incident diabetes were examined using Cox proportional hazard models. Models were adjusted for age, sex, education, occupation, systolic blood pressure, smoking, physical activity, dietary intake, alcohol use and adiponectin. Results Aldosterone and the combined aldosterone-endothelin score were positively associated with FPG, HOMA-IR, and HOMA-β (all p < 0.05). Endothelin-1 was negatively associated with FPG but positively associated with HOMA-β (both p < 0.05). Only the aldosterone-endothelin score was positively associated with HbA1c (p < 0.01). A 1-SD higher serum aldosterone and endothelin-1 was associated with a 22 % and 14 % higher risk of incident diabetes, respectively, while a 1-point higher aldosterone-endothelin score was associated with a 13 % higher risk of incident diabetes after adjustment for diabetes risk factors (all p < 0.01). Conclusions Aldosterone and endothelin-1, factors integral in blood pressure regulation, may play a significant role in the development of diabetes among AAs.
Collapse
Affiliation(s)
- Joshua J. Joseph
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Bjorn Kluwe
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Songzhu Zhao
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University College of Medicine, Columbus, OH, USA
| | - David Kline
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Divya Nedungadi
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Guy Brock
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Willa A. Hsueh
- Division of Endocrinology, Diabetes and Metabolism, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Sherita H. Golden
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Columbus, OH, USA
| |
Collapse
|
3
|
Incorporation of Oxidized Phenylalanine Derivatives into Insulin Signaling Relevant Proteins May Link Oxidative Stress to Signaling Conditions Underlying Chronic Insulin Resistance. Biomedicines 2022; 10:biomedicines10050975. [PMID: 35625712 PMCID: PMC9138545 DOI: 10.3390/biomedicines10050975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 12/12/2022] Open
Abstract
A link between oxidative stress and insulin resistance has been suggested. Hydroxyl free radicals are known to be able to convert phenylalanine (Phe) into the non-physiological tyrosine isoforms ortho- and meta-tyrosine (o-Tyr, m-Tyr). The aim of our study was to examine the role of o-Tyr and m-Tyr in the development of insulin resistance. We found that insulin-induced uptake of glucose was blunted in cultures of 3T3-L1 grown on media containing o- or m-Tyr. We show that these modified amino acids are incorporated into cellular proteins. We focused on insulin receptor substrate 1 (IRS-1), which plays a role in insulin signaling. The activating phosphorylation of IRS-1 was increased by insulin, the effect of which was abolished in cells grown in m-Tyr or o-Tyr media. We found that phosphorylation of m- or o-Tyr containing IRS-1 segments by insulin receptor (IR) kinase was greatly reduced, PTP-1B phosphatase was incapable of dephosphorylating phosphorylated m- or o-Tyr IRS-1 peptides, and the SH2 domains of phosphoinositide 3-kinase (PI3K) bound the o-Tyr IRS-1 peptides with greatly reduced affinity. According to our data, m- or o-Tyr incorporation into IRS-1 modifies its protein–protein interactions with regulating enzymes and effectors, thus IRS-1 eventually loses its capacity to play its role in insulin signaling, leading to insulin resistance.
Collapse
|
4
|
Lien CC, Yin WH, Yang DM, Chen LK, Chen CW, Liu SY, Kwok CF, Ho LT, Juan CC. Endothelin-1 induces lipolysis through activation of the GC/cGMP/Ca 2+/ERK/CaMKIII pathway in 3T3-L1 adipocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159071. [PMID: 34748972 DOI: 10.1016/j.bbalip.2021.159071] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 10/24/2021] [Accepted: 11/03/2021] [Indexed: 02/07/2023]
Abstract
Endothelin-1 (ET-1) is a potent vasoconstrictive peptide produced and secreted mainly by endothelial cells. Recent studies indicate that ET-1 can regulate lipid metabolism, which may increase the risk of insulin resistance. Our previous studies revealed that ET-1 induced lipolysis in adipocytes, but the underlying mechanisms were unclear. 3T3-L1 adipocytes were used to investigate the effect of ET-1 on lipolysis and the underlying mechanisms. Glycerol levels in the incubation medium and hormone-sensitive lipase (HSL) phosphorylation were used as indices for lipolysis. ET-1 significantly increased HSL phosphorylation and lipolysis, which were completely inhibited by ERK inhibitor (PD98059) and guanylyl cyclase (GC) inhibitor (LY83583). LY83583 reduced ET-1-induced ERK phosphorylation. A Ca2+-free medium and PLC inhibitor caused significant decreases in ET-1-induced lipolysis as well as ERK and HSL phosphorylation, and IP3 receptor activator (D-IP3) increased lipolysis. ET-1 increased cGMP production, which was not affected by depletion of extracellular Ca2+. On the other hand, LY83583 diminished the ET-1-induced Ca2+ influx. Transient receptor potential vanilloid-1 (TRPV-1) antagonist and shRNA partially inhibited ET-1-induced lipolysis. ET-1-induced lipolysis was completely suppressed by CaMKIII inhibitor (NH-125). These results indicate that ET-1 stimulates extracellular Ca2+ entry and activates the intracellular PLC/IP3/Ca2+ pathway through a cGMP-dependent pathway. The increased cytosolic Ca2+ that results from ET-1 treatment stimulates ERK and HSL phosphorylation, which subsequently induces lipolysis. ET-1 induces HSL phosphorylation and lipolysis via the GC/cGMP/Ca2+/ERK/CaMKIII signaling pathway in 3T3-L1 adipocytes.
Collapse
Affiliation(s)
- Chih-Chan Lien
- Institutes of Physiology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Department of Life Science, College of Science, Chinese Culture University, Taipei, Taiwan
| | - Wei-Hsian Yin
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Division of Cardiology, Cheng-Hsin General Hospital, Taipei, Taiwan; Heart Center, Cheng-Hsin General Hospital, Taipei, Taiwan
| | - De-Ming Yang
- Institute of Biophotonics, College of Biomedical Science and Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan; Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Luen-Kui Chen
- Institutes of Physiology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chien-Wei Chen
- College of Human Development and Health, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Shui-Yu Liu
- Institutes of Physiology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ching-Fai Kwok
- Division of Metabolism, Cheng-Hsin General Hospital, Taipei, Taiwan; Division of Endocrinology and Metabolism, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Low-Tone Ho
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan; Division of Endocrinology and Metabolism, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chi-Chang Juan
- Institutes of Physiology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
| |
Collapse
|
5
|
Luk C, Haywood NJ, Bridge KI, Kearney MT. Paracrine Role of the Endothelium in Metabolic Homeostasis in Health and Nutrient Excess. Front Cardiovasc Med 2022; 9:882923. [PMID: 35557517 PMCID: PMC9086712 DOI: 10.3389/fcvm.2022.882923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 04/04/2022] [Indexed: 02/02/2023] Open
Abstract
The vascular endothelium traditionally viewed as a simple physical barrier between the circulation and tissue is now well-established as a key organ mediating whole organism homeostasis by release of a portfolio of anti-inflammatory and pro-inflammatory vasoactive molecules. Healthy endothelium releases anti-inflammatory signaling molecules such as nitric oxide and prostacyclin; in contrast, diseased endothelium secretes pro-inflammatory signals such as reactive oxygen species, endothelin-1 and tumor necrosis factor-alpha (TNFα). Endothelial dysfunction, which has now been identified as a hallmark of different components of the cardiometabolic syndrome including obesity, type 2 diabetes and hypertension, initiates and drives the progression of tissue damage in these disorders. Recently it has become apparent that, in addition to vasoactive molecules, the vascular endothelium has the potential to secrete a diverse range of small molecules and proteins mediating metabolic processes in adipose tissue (AT), liver, skeletal muscle and the pancreas. AT plays a pivotal role in orchestrating whole-body energy homeostasis and AT dysfunction, characterized by local and systemic inflammation, is central to the metabolic complications of obesity. Thus, understanding and targeting the crosstalk between the endothelium and AT may generate novel therapeutic opportunities for the cardiometabolic syndrome. Here, we provide an overview of the role of the endothelial secretome in controlling the function of AT. The endothelial-derived metabolic regulatory factors are grouped and discussed based on their physical properties and their downstream signaling effects. In addition, we focus on the therapeutic potential of these regulatory factors in treating cardiometabolic syndrome, and discuss areas of future study of potential translatable and clinical significance. The vascular endothelium is emerging as an important paracrine/endocrine organ that secretes regulatory factors in response to nutritional and environmental cues. Endothelial dysfunction may result in imbalanced secretion of these regulatory factors and contribute to the progression of AT and whole body metabolic dysfunction. As the vascular endothelium is the first responder to local nutritional changes and adipocyte-derived signals, future work elucidating the changes in the endothelial secretome is crucial to improve our understanding of the pathophysiology of cardiometabolic disease, and in aiding our development of new therapeutic strategies to treat and prevent cardiometabolic syndrome.
Collapse
Affiliation(s)
- Cheukyau Luk
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, United Kingdom
| | - Natalie J Haywood
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, United Kingdom
| | - Katherine I Bridge
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, United Kingdom
| | - Mark T Kearney
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, United Kingdom
| |
Collapse
|
6
|
Onken MD, Noda SE, Kaltenbronn KM, Frankfater C, Makepeace CM, Fettig N, Piggott KD, Custer PL, Ippolito JE, Blumer KJ. Oncogenic Gq/11 signaling acutely drives and chronically sustains metabolic reprogramming in uveal melanoma. J Biol Chem 2022; 298:101495. [PMID: 34919964 PMCID: PMC8761705 DOI: 10.1016/j.jbc.2021.101495] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/04/2021] [Accepted: 12/06/2021] [Indexed: 12/02/2022] Open
Abstract
Metabolic reprogramming has been shown to occur in uveal melanoma (UM), the most common intraocular tumor in adults. Mechanisms driving metabolic reprogramming in UM are poorly understood. Elucidation of these mechanisms could inform development of new therapeutic strategies for metastatic UM, which has poor prognosis because existing therapies are ineffective. Here, we determined whether metabolic reprogramming is driven by constitutively active mutant α-subunits of the heterotrimeric G proteins Gq or G11 (Gq/11), the oncogenic drivers in ∼90% of UM patients. Using PET-computed tomography imaging, microphysiometry, and GC/MS, we found that inhibition of oncogenic Gq/11 with the small molecule FR900359 (FR) attenuated glucose uptake by UM cells in vivo and in vitro, blunted glycolysis and mitochondrial respiration in UM cell lines and tumor cells isolated from patients, and reduced levels of several glycolytic and tricarboxylic acid cycle intermediates. FR acutely inhibited glycolysis and respiration and chronically attenuated expression of genes in both metabolic processes. UM therefore differs from other melanomas that exhibit a classic Warburg effect. Metabolic reprogramming in UM cell lines and patient samples involved protein kinase C and extracellular signal-regulated protein kinase 1/2 signaling downstream of oncogenic Gq/11. Chronic administration of FR upregulated expression of genes involved in metabolite scavenging and redox homeostasis, potentially as an adaptive mechanism explaining why FR does not efficiently kill UM tumor cells or regress UM tumor xenografts. These results establish that oncogenic Gq/11 signaling is a crucial driver of metabolic reprogramming in UM and lay a foundation for studies aimed at targeting metabolic reprogramming for therapeutic development.
Collapse
Affiliation(s)
- Michael D Onken
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri, USA
| | - Sarah E Noda
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Kevin M Kaltenbronn
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Cheryl Frankfater
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri, USA; Department of Radiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Carol M Makepeace
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Nikki Fettig
- Department of Radiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Kisha D Piggott
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, Missouri, USA
| | - Philip L Custer
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, Missouri, USA
| | - Joseph E Ippolito
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri, USA; Department of Radiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Kendall J Blumer
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri, USA.
| |
Collapse
|
7
|
Xu J, Kitada M, Ogura Y, Koya D. Relationship Between Autophagy and Metabolic Syndrome Characteristics in the Pathogenesis of Atherosclerosis. Front Cell Dev Biol 2021; 9:641852. [PMID: 33937238 PMCID: PMC8083902 DOI: 10.3389/fcell.2021.641852] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/19/2021] [Indexed: 12/11/2022] Open
Abstract
Atherosclerosis is the main cause of mortality in metabolic-related diseases, including cardiovascular disease and type 2 diabetes (T2DM). Atherosclerosis is characterized by lipid accumulation and increased inflammatory cytokines in the vascular wall, endothelial cell and vascular smooth muscle cell dysfunction and foam cell formation initiated by monocytes/macrophages. The characteristics of metabolic syndrome (MetS), including obesity, glucose intolerance, dyslipidemia and hypertension, may activate multiple mechanisms, such as insulin resistance, oxidative stress and inflammatory pathways, thereby contributing to increased risks of developing atherosclerosis and T2DM. Autophagy is a lysosomal degradation process that plays an important role in maintaining cellular metabolic homeostasis. Increasing evidence indicates that impaired autophagy induced by MetS is related to oxidative stress, inflammation, and foam cell formation, further promoting atherosclerosis. Basal and mild adaptive autophagy protect against the progression of atherosclerotic plaques, while excessive autophagy activation leads to cell death, plaque instability or even plaque rupture. Therefore, autophagic homeostasis is essential for the development and outcome of atherosclerosis. Here, we discuss the potential role of autophagy and metabolic syndrome in the pathophysiologic mechanisms of atherosclerosis and potential therapeutic drugs that target these molecular mechanisms.
Collapse
Affiliation(s)
- Jing Xu
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Japan.,Department of Endocrinology and Metabolism, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Munehiro Kitada
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Japan.,Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Japan
| | - Yoshio Ogura
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Japan
| | - Daisuke Koya
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Japan.,Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Japan
| |
Collapse
|
8
|
Polak J, Punjabi NM, Shimoda LA. Blockade of Endothelin-1 Receptor Type B Ameliorates Glucose Intolerance and Insulin Resistance in a Mouse Model of Obstructive Sleep Apnea. Front Endocrinol (Lausanne) 2018; 9:280. [PMID: 29896159 PMCID: PMC5986958 DOI: 10.3389/fendo.2018.00280] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 05/11/2018] [Indexed: 01/17/2023] Open
Abstract
Obstructive sleep apnea (OSA) is associated with insulin resistance (IR) and glucose intolerance. Elevated endothelin-1 (ET-1) levels have been observed in OSA patients and in mice exposed to intermittent hypoxia (IH). We examined whether pharmacological blockade of type A and type B ET-1 receptors (ETA and ETB) would ameliorate glucose intolerance and IR in mice exposed to IH. Subcutaneously implanted pumps delivered BQ-123 (ETA antagonist; 200 nmol/kg/day), BQ-788 (ETB antagonist; 200 nmol/kg/day) or vehicle (saline or propyleneglycol [PG]) for 14 days in C57BL6/J mice (10/group). During treatment, mice were exposed to IH (decreasing the FiO2 from 20.9% to 6%, 60/h) or intermittent air (IA). After IH or IA exposure, insulin (0.5 IU/kg) or glucose (1 mg/kg) was injected intraperitoneally and plasma glucose determined after injection and area under glucose curve (AUC) was calculated. Fourteen-day IH increased fasting glucose levels (122 ± 7 vs. 157 ± 8 mg/dL, PG: 118 ± 6 vs. 139 ± 8; both p < 0.05) and impaired glucose tolerance (AUCglucose: 19,249 ± 1105 vs. 29,124 ± 1444, PG AUCglucose: 18,066 ± 947 vs. 25,135 ± 797; both p < 0.05) in vehicle-treated animals. IH-induced impairments in glucose tolerance were partially ameliorated with BQ-788 treatment (AUCglucose: 21,969 ± 662; p < 0.05). Fourteen-day IH also induced IR (AUCglucose: 7185 ± 401 vs. 8699 ± 401; p < 0.05). Treatment with BQ-788 decreased IR under IA (AUCglucose: 5281 ± 401, p < 0.05) and reduced worsening of IR with IH (AUCglucose: 7302 ± 401, p < 0.05). There was no effect of BQ-123 on IH-induced impairments in glucose tolerance or IR. Our results suggest that ET-1 plays a role in IH-induced impairments in glucose homeostasis.
Collapse
Affiliation(s)
- Jan Polak
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, United States
- Department for the Study of Obesity and Diabetes, Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Naresh M. Punjabi
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Larissa A. Shimoda
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, United States
| |
Collapse
|
9
|
Targeting endothelial metaflammation to counteract diabesity cardiovascular risk: Current and perspective therapeutic options. Pharmacol Res 2017; 120:226-241. [PMID: 28408314 DOI: 10.1016/j.phrs.2017.04.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/21/2017] [Accepted: 04/07/2017] [Indexed: 02/08/2023]
Abstract
The association of obesity and diabetes, termed "diabesity", defines a combination of primarily metabolic disorders with insulin resistance as the underlying common pathophysiology. Cardiovascular disorders associated with diabesity represent the leading cause of morbidity and mortality in the Western world. This makes diabesity, with its rising impacts on both health and economics, one of the most challenging biomedical and social threats of present century. The emerging comprehension of the genes whose alteration confers inter-individual differences on risk factors for diabetes or obesity, together with the potential role of genetically determined variants on mechanisms controlling responsiveness, effectiveness and safety of anti-diabetic therapy underlines the need of additional knowledge on molecular mechanisms involved in the pathophysiology of diabesity. Endothelial cell dysfunction, resulting from the unbalanced production of endothelial-derived vascular mediators, is known to be present at the earliest stages of insulin resistance and obesity, and may precede the clinical diagnosis of diabetes by several years. Once considered as a mere consequence of metabolic abnormalities, it is now clear that endothelial dysfunctional activity may play a pivotal role in the progression of diabesity. In the vicious circle where vascular defects and metabolic disturbances worsen and reinforce each other, a low-grade, chronic, and 'cold' inflammation (metaflammation) has been suggested to serve as the pathophysiological link that binds endothelial and metabolic dysfunctions. In this paradigm, it is important to consider how traditional antidiabetic treatments (specifically addressing metabolic dysregulation) may directly impact on inflammatory processes or cardiovascular function. Indeed, not all drugs currently available to treat diabetes possess the same anti-inflammatory potential, or target endothelial cell function equally. Perspective strategies pointing at reducing metaflammation or directly addressing endothelial dysfunction may disclose beneficial consequences on metabolic regulation. This review focuses on existing and potential new approaches ameliorating endothelial dysfunction and vascular inflammation in the context of diabesity.
Collapse
|
10
|
Mangmool S, Denkaew T, Parichatikanond W, Kurose H. β-Adrenergic Receptor and Insulin Resistance in the Heart. Biomol Ther (Seoul) 2017; 25:44-56. [PMID: 28035081 PMCID: PMC5207462 DOI: 10.4062/biomolther.2016.128] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/26/2016] [Accepted: 08/02/2016] [Indexed: 12/24/2022] Open
Abstract
Insulin resistance is characterized by the reduced ability of insulin to stimulate tissue uptake and disposal of glucose including cardiac muscle. These conditions accelerate the progression of heart failure and increase cardiovascular morbidity and mortality in patients with cardiovascular diseases. It is noteworthy that some conditions of insulin resistance are characterized by up-regulation of the sympathetic nervous system, resulting in enhanced stimulation of β-adrenergic receptor (βAR). Overstimulation of βARs leads to the development of heart failure and is associated with the pathogenesis of insulin resistance in the heart. However, pathological consequences of the cross-talk between the βAR and the insulin sensitivity and the mechanism by which βAR overstimulation promotes insulin resistance remain unclear. This review article examines the hypothesis that βARs overstimulation leads to induction of insulin resistance in the heart.
Collapse
Affiliation(s)
- Supachoke Mangmool
- Department of Pharmacology, Faculty of Pharmacy, Mahidol University, Bangkok 10400, Thailand.,Center of Excellence for Innovation in Drug Design and Discovery, Faculty of Pharmacy, Mahidol University, Bangkok 10400, Thailand
| | - Tananat Denkaew
- Department of Pharmacology, Faculty of Pharmacy, Mahidol University, Bangkok 10400, Thailand
| | | | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| |
Collapse
|
11
|
Mahmoud AM, Brown MD, Phillips SA, Haus JM. Skeletal Muscle Vascular Function: A Counterbalance of Insulin Action. Microcirculation 2016; 22:327-47. [PMID: 25904196 DOI: 10.1111/micc.12205] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/20/2015] [Indexed: 12/11/2022]
Abstract
Insulin is a vasoactive hormone that regulates vascular homeostasis by maintaining balance of endothelial-derived NO and ET-1. Although there is general agreement that insulin resistance and the associated hyperinsulinemia disturb this balance, the vascular consequences for hyperinsulinemia in isolation from insulin resistance are still unclear. Presently, there is no simple answer for this question, especially in a background of mixed reports examining the effects of experimental hyperinsulinemia on endothelial-mediated vasodilation. Understanding the mechanisms by which hyperinsulinemia induces vascular dysfunction is essential in advancing treatment and prevention of insulin resistance-related vascular complications. Thus, we review literature addressing the effects of hyperinsulinemia on vascular function. Furthermore, we give special attention to the vasoregulatory effects of hyperinsulinemia on skeletal muscle, the largest insulin-dependent organ in the body. This review also characterizes the differential vascular effects of hyperinsulinemia on large conduit vessels versus small resistance microvessels and the effects of metabolic variables in an effort to unravel potential sources of discrepancies in the literature. At the cellular level, we provide an overview of insulin signaling events governing vascular tone. Finally, we hypothesize a role for hyperinsulinemia and insulin resistance in the development of CVD.
Collapse
Affiliation(s)
- Abeer M Mahmoud
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.,Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Michael D Brown
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.,Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Shane A Phillips
- Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.,Department of Physical Therapy, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Jacob M Haus
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.,Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| |
Collapse
|
12
|
Briançon-Marjollet A, Monneret D, Henri M, Hazane-Puch F, Pepin JL, Faure P, Godin-Ribuot D. Endothelin regulates intermittent hypoxia-induced lipolytic remodelling of adipose tissue and phosphorylation of hormone-sensitive lipase. J Physiol 2016; 594:1727-40. [PMID: 26663321 DOI: 10.1113/jp271321] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 12/08/2015] [Indexed: 12/23/2022] Open
Abstract
Obstructive sleep apnoea syndrome is characterized by repetitive episodes of upper airway collapse during sleep resulting in chronic intermittent hypoxia (IH). Obstructive sleep apnoea syndrome, through IH, promotes cardiovascular and metabolic disorders. Endothelin-1 (ET-1) secretion is upregulated by IH, and is able to modulate adipocyte metabolism. Therefore, the present study aimed to characterize the role of ET-1 in the metabolic consequences of IH on adipose tissue in vivo and in vitro. Wistar rats were submitted to 14 days of IH-cycles (30 s of 21% FiO2 and 30 s of 5% FiO2 ; 8 h day(-1) ) or normoxia (air-air cycles) and were treated or not with bosentan, a dual type A and B endothelin receptor (ETA-R and ETB-R) antagonist. Bosentan treatment decreased plasma free fatty acid and triglyceride levels, and inhibited IH-induced lipolysis in adipose tissue. Moreover, IH induced a 2-fold increase in ET-1 transcription and ETA-R expression in adipose tissue that was reversed by bosentan. In 3T3-L1 adipocytes, ET-1 upregulated its own and its ETA-R transcription and this effect was abolished by bosentan. Moreover, ET-1 induced glycerol release and inhibited insulin-induced glucose uptake. Bosentan and BQ123 inhibited these effects. Bosentan also reversed the ET-1-induced phosphorylation of hormone-sensitive lipase (HSL) on Ser(660) . Finally, ET-1-induced lipolysis and HSL phosphorylation were also observed under hypoxia. Altogether, these data suggest that ET-1 is involved in IH-induced lipolysis in Wistar rats, and that upregulation of ET-1 production and ETA-R expression by ET-1 itself under IH could amplify its effects. Moreover, ET-1-induced lipolysis could be mediated through ETA-R and activation of HSL by Ser(660) phosphorylation.
Collapse
Affiliation(s)
| | - Denis Monneret
- Université Grenoble Alpes, HP2, Grenoble, France.,INSERM, HP2, U1042, Grenoble, France.,CHU Grenoble, Departement of Biochemistry, Toxicology and Pharmacology, Biology Pole, Grenoble, France.,Present address: Department of Metabolic Biochemistry, La Pitié Salpêtrière-Charles Foix University Hospital (AP-HP), Paris, France
| | - Marion Henri
- Université Grenoble Alpes, HP2, Grenoble, France.,INSERM, HP2, U1042, Grenoble, France
| | - Florence Hazane-Puch
- CHU Grenoble, Departement of Biochemistry, Toxicology and Pharmacology, Biology Pole, Grenoble, France
| | - Jean-Louis Pepin
- Université Grenoble Alpes, HP2, Grenoble, France.,INSERM, HP2, U1042, Grenoble, France.,CHU Grenoble, EFCR Laboratory, Thorax and vessels pole, Grenoble, France
| | - Patrice Faure
- Université Grenoble Alpes, HP2, Grenoble, France.,INSERM, HP2, U1042, Grenoble, France.,CHU Grenoble, Departement of Biochemistry, Toxicology and Pharmacology, Biology Pole, Grenoble, France
| | - Diane Godin-Ribuot
- Université Grenoble Alpes, HP2, Grenoble, France.,INSERM, HP2, U1042, Grenoble, France
| |
Collapse
|
13
|
Chai SP, Fong JC. Synergistic induction of insulin resistance by endothelin-1 and cAMP in 3T3-L1 adipocytes. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2048-55. [PMID: 26143144 DOI: 10.1016/j.bbadis.2015.06.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/30/2015] [Accepted: 06/25/2015] [Indexed: 12/27/2022]
Abstract
Both endothelin-1 (ET-1) and cAMP are implicated for inducing insulin resistance. Since we have shown previously that there is a crosstalk between ET-1 and cAMP signaling pathways in regulating glucose uptake in 3T3-L1 adipocytes, we extended our investigation in this study on whether they may have a synergistic effect on inducing insulin resistance. Our results showed that it was indeed the case. Insulin-stimulated glucose uptake, phosphorylation of PKB, IRS-1-associated PI3K, and IRS-1 tyrosine phosphorylation were all inhibited by ET-1 and 8-bromo cAMP in a synergistic manner. IRS-1 protein levels were similarly decreased by ET-1 and 8-bromo cAMP, attributable to suppressed mRNA expression. In addition, after correction for the loss in IRS-1 protein, the inhibition of insulin-stimulated IRS-1 tyrosine phosphorylation or IRS-1-associated PI3K was mainly caused by cAMP. Moreover, whereas IRS-2 protein levels were increased by cAMP or ET-1 plus cAMP, insulin-stimulated IRS-2-associated PI3K activities were abolished by both treatments. Furthermore, ET-1 and β-adrenergic agonists had similar synergistic inhibition on insulin-stimulated glucose uptake. In conclusion, we have shown that ET-1 and cAMP may synergistically induce insulin resistance in adipocytes via inhibiting IRS-1 expression as well as insulin-stimulated IRS-1/IRS-2 activities.
Collapse
Affiliation(s)
- Shin-Pei Chai
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan, ROC
| | - Jim C Fong
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan, ROC.
| |
Collapse
|
14
|
Papaetis GS, Papakyriakou P, Panagiotou TN. Central obesity, type 2 diabetes and insulin: exploring a pathway full of thorns. Arch Med Sci 2015; 11:463-82. [PMID: 26170839 PMCID: PMC4495144 DOI: 10.5114/aoms.2015.52350] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 06/20/2013] [Accepted: 07/04/2013] [Indexed: 12/19/2022] Open
Abstract
The prevalence of type 2 diabetes (T2D) is rapidly increasing. This is strongly related to the contemporary lifestyle changes that have resulted in increased rates of overweight individuals and obesity. Central (intra-abdominal) obesity is observed in the majority of patients with T2D. It is associated with insulin resistance, mainly at the level of skeletal muscle, adipose tissue and liver. The discovery of macrophage infiltration in the abdominal adipose tissue and the unbalanced production of adipocyte cytokines (adipokines) was an essential step towards novel research perspectives for a better understanding of the molecular mechanisms governing the development of insulin resistance. Furthermore, in an obese state, the increased cellular uptake of non-esterified fatty acids is exacerbated without any subsequent β-oxidation. This in turn contributes to the accumulation of intermediate lipid metabolites that cause defects in the insulin signaling pathway. This paper examines the possible cellular mechanisms that connect central obesity with defects in the insulin pathway. It discusses the discrepancies observed from studies organized in cell cultures, animal models and humans. Finally, it emphasizes the need for therapeutic strategies in order to achieve weight reduction in overweight and obese patients with T2D.
Collapse
Affiliation(s)
- Georgios S. Papaetis
- Diabetes Clinic, Paphos, Cyprus
- Diabetes Clinic, 3 Department of Medicine, University of Athens Medical School, ‘Sotiria’ General Hospital, Athens, Greece
| | | | - Themistoklis N. Panagiotou
- Diabetes Clinic, 3 Department of Medicine, University of Athens Medical School, ‘Sotiria’ General Hospital, Athens, Greece
| |
Collapse
|
15
|
Martin-Conejero A, Modrego Martín J, Hernández Mateo M, Rodríguez Sierra P, Serrano Hernando F, López Farré A. Efectos del bosentán sobre la función vascular e inflamación de pacientes diabéticos con enfermedad vascular periférica. ANGIOLOGIA 2015. [DOI: 10.1016/j.angio.2014.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
16
|
Campia U, Tesauro M, Di Daniele N, Cardillo C. The vascular endothelin system in obesity and type 2 diabetes: Pathophysiology and therapeutic implications. Life Sci 2014; 118:149-55. [DOI: 10.1016/j.lfs.2014.02.028] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/05/2014] [Accepted: 02/20/2014] [Indexed: 12/29/2022]
|
17
|
Czech MP, Tencerova M, Pedersen DJ, Aouadi M. Insulin signalling mechanisms for triacylglycerol storage. Diabetologia 2013; 56:949-64. [PMID: 23443243 PMCID: PMC3652374 DOI: 10.1007/s00125-013-2869-1] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/22/2013] [Indexed: 02/06/2023]
Abstract
Insulin signalling is uniquely required for storing energy as fat in humans. While de novo synthesis of fatty acids and triacylglycerol occurs mostly in liver, adipose tissue is the primary site for triacylglycerol storage. Insulin signalling mechanisms in adipose tissue that stimulate hydrolysis of circulating triacylglycerol, uptake of the released fatty acids and their conversion to triacylglycerol are poorly understood. New findings include (1) activation of DNA-dependent protein kinase to stimulate upstream stimulatory factor (USF)1/USF2 heterodimers, enhancing the lipogenic transcription factor sterol regulatory element binding protein 1c (SREBP1c); (2) stimulation of fatty acid synthase through AMP kinase modulation; (3) mobilisation of lipid droplet proteins to promote retention of triacylglycerol; and (4) upregulation of a novel carbohydrate response element binding protein β isoform that potently stimulates transcription of lipogenic enzymes. Additionally, insulin signalling through mammalian target of rapamycin to activate transcription and processing of SREBP1c described in liver may apply to adipose tissue. Paradoxically, insulin resistance in obesity and type 2 diabetes is associated with increased triacylglycerol synthesis in liver, while it is decreased in adipose tissue. This and other mysteries about insulin signalling and insulin resistance in adipose tissue make this topic especially fertile for future research.
Collapse
Affiliation(s)
- M P Czech
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
| | | | | | | |
Collapse
|
18
|
Nacci C, Leo V, De Benedictis L, Carratù MR, Bartolomeo N, Altomare M, Giordano P, Faienza MF, Montagnani M. Elevated endothelin-1 (ET-1) levels may contribute to hypoadiponectinemia in childhood obesity. J Clin Endocrinol Metab 2013; 98:E683-93. [PMID: 23457411 DOI: 10.1210/jc.2012-4119] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
CONTEXT Pediatric obesity is associated with endothelial dysfunction and hypoadiponectinemia, but the relationship between these two conditions remains to be fully clarified. Whether enhanced release of endothelin-1 (ET-1) may directly impair adiponectin (Ad) production in obese children is not known. OBJECTIVE The aim of the study was to explore whether and how high circulating levels of ET-1 may contribute to impair Ad production, release, and vascular activity. DESIGN AND PARTICIPANTS Sixty children were included into obese (Ob; n = 30), overweight (OW; n = 11), and lean (n = 19) groups. Total and high-molecular-weight Ad, ET-1, vascular cell adhesion molecule-1, and von Willebrand factor levels were measured in serum samples. Adipocytes were stimulated with exogenous ET-1 or with sera from lean, OW, and Ob, and Ad production and release measured in the absence or in the presence of ETA (BQ-123) and ETB (BQ-788) receptor blockers, p42/44 MAPK inhibitor PD-98059, or c-Jun NH2-terminal protein kinase inhibitor SP-600125. Vasodilation to Ad was evaluated in rat isolated arteries in the absence or in the presence of BQ-123/788. RESULTS Total and high-molecular-weight Ad was significantly decreased and ET-1 levels significantly increased in OW (P < .01) and Ob (P < .001) children. A statistically significant linear regression (P < .01) was found between Ad and ET-1. Exposure of adipocytes to exogenous ET-1 or serum from OW and Ob significantly decreased Ad mRNA and protein levels (P < 0.001). The inhibitory effect of ET-1 on Ad was reverted by BQ-123/788 or PD-98059 but not SP-600125. Ad-mediated vasodilation was further increased in arteries pretreated with BQ-123/788. CONCLUSIONS ET-1-mediated inhibition of Ad synthesis via p42/44 MAPK signaling may provide a possible explanation for hypoadiponectinemia in pediatric obesity and contribute to the development of cardiovascular complications.
Collapse
Affiliation(s)
- Carmela Nacci
- Department of Biomedical Sciences and Human Oncology, University of Bari, Medical School, 70124 Bari, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Dai M, Freeman B, Bruno FP, Shikani HJ, Tanowitz HB, Weiss LM, Reznik SE, Stephani RA, Desruisseaux MS. The novel ETA receptor antagonist HJP-272 prevents cerebral microvascular hemorrhage in cerebral malaria and synergistically improves survival in combination with an artemisinin derivative. Life Sci 2012; 91:687-92. [PMID: 22820174 PMCID: PMC3523882 DOI: 10.1016/j.lfs.2012.07.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 06/28/2012] [Accepted: 07/06/2012] [Indexed: 11/30/2022]
Abstract
AIM To investigate the association between vasculopathy and survival during experimental cerebral malaria (ECM), and to determine whether targeting the endothelin-1 (ET-1) pathway alone or in combination with the anti-malaria drug artemether (a semi-synthetic derivative of artemisinin) will improve microvascular hemorrhage and survival. MAIN METHODS C57BL/6 mice infected with Plasmodium berghei ANKA (PbA) were randomly assigned to four groups: no treatment, artemether treated, ET(A) receptor antagonist (HJP-272) treated, or HJP-272 and artemether treated. The uninfected control mice were treated with HJP-272 and artemether. We analyzed survival, cerebral hemorrhage, weight change, blood glucose levels and parasitemia. KEY FINDINGS Our studies demonstrated decreased brain hemorrhage in PbA-infected (ECM) mice treated when HJP-272, a 1,3,6-trisubstituted-2-carboxy-quinol-4-one novel ET(A) receptor antagonist synthesized by our group, is used in conjunction with artemether, an anti-malarial agent. In addition, despite adversely affecting parasitemia and weight in non-artemether treated infected mice, HJP-272, seemed to confer some survival benefit when used as adjunctive therapy, though this did not reach significance. SIGNIFICANCE Previous studies demonstrate that the endothelin pathway is associated with vasculopathy, neuronal injury and inflammation in ECM. As demonstrated here, components of the ET-1 pathway may be important targets for adjunctive therapy in ECM, and may help in preventing hemorrhage and in improving survival when used as adjunctive therapy during malaria infection. The data presented suggest that our novel agent, HJP-272, may ameliorate alterations in the vasculature which can potentially lead to inflammation, neurological dysfunction, and subsequent death in mice with ECM.
Collapse
Affiliation(s)
- Minxian Dai
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Brandi Freeman
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Fernando P. Bruno
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Henry J. Shikani
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Herbert B. Tanowitz
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Louis M. Weiss
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Sandra E. Reznik
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, St. John’s University, Queens, New York, United States of America
| | - Ralph A. Stephani
- Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, St. John’s University, Queens, New York, United States of America
| | - Mahalia S. Desruisseaux
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| |
Collapse
|
20
|
Brame LA, Considine RV, Yamauchi M, Baron AD, Mather KJ. Insulin and Endothelin in the Acute Regulation of Adiponectin in Vivo in Humans. ACTA ACUST UNITED AC 2012; 13:582-8. [PMID: 15833944 DOI: 10.1038/oby.2005.62] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE In vitro, insulin and endothelin (ET) both modulate adiponectin secretion from adipocyte cell lines. The current studies were performed to assess whether endogenous ET contributes to the acute action of insulin infusions on adiponectin levels in vivo in humans. RESEARCH METHODS AND PROCEDURES We studied 17 lean and 20 obese subjects (BMI 21.8 +/- 2.2 and 34.0 +/- 5.0 kg/m(2), respectively). Hyperinsulinemic euglycemic clamp studies were performed using insulin infusion rates of 10, 30, or 300 mU/m(2) per minute alone or with concurrent infusion of BQ123, an antagonist of type A ET receptors. Circulating adiponectin levels were assessed at baseline and after achievement of steady-state glucose with the insulin infusion. RESULTS Adiponectin levels were lower in obese than lean subjects (6.76 +/- 3.66 vs. 8.37 +/- 2.79 microg/mL, p = 0.0148 adjusted for differences across gender). Insulin infusions suppressed adiponectin by a mean of 7.8% (p < 0.0001). In a subset of 13 lean and 14 obese subjects for whom data with and without BQ123 were available, there was no evident effect of BQ123 to modulate clamp-associated suppression of adiponectin (p = 0.16). Surprisingly, there was no evident relationship between steady-state insulin concentrations and adiponectin suppression (r = 0.14, p = 0.30), and again no effect of BQ123 to modify this relationship was seen. DISCUSSION Despite baseline differences in adiponectin levels, we observed equal suppression of adiponectin with insulin infusions in lean and obese subjects. ET receptor antagonism with BQ123 did not modulate this effect, suggesting that endogenous ET does not have a role in modifying the acute effects of insulin on adiponectin production and/or disposition.
Collapse
Affiliation(s)
- Lori A Brame
- Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | | | | | | |
Collapse
|
21
|
Ho PC, Tsui YC, Lin YW, Persaud SD, Wei LN. Endothelin-1 promotes cytoplasmic accumulation of RIP140 through a ET(A)-PLCβ-PKCε pathway. Mol Cell Endocrinol 2012; 351:176-83. [PMID: 22209746 PMCID: PMC3288750 DOI: 10.1016/j.mce.2011.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 11/15/2011] [Accepted: 12/02/2011] [Indexed: 01/14/2023]
Abstract
The physiological signal activating cytoplasmic accumulation of nuclear receptor interacting protein 140 (RIP140) in adipocytes was unclear. We uncover that endothelin-1 (ET-1) promotes cytoplasmic accumulation of RIP140 in 3T3-L1 adipocytes. We determine ET-1's signal transduction pathway in adipocytes, which is by activating ET(A) receptor-PLCβ-nuclear PKCε. Blocking this pathway in 3T3-L1 adipocyte cultures, by treating cells with an ET(A) antagonist, inhibiting PLCβ, or silencing PKCε, reduces ET-1-stimulated cytoplasmic accumulation of RIP140. In a HFD-fed obese mouse model, administration of a selective ET(A) antagonist, ambrisentan, effectively dampens cytoplasmic accumulation of RIP140 in the epididymal adipose tissue and reduces HFD-caused adipocyte dysfunctions. Importantly, ambrisentan improves blood glucose control and reduces the severity of hepatic steatosis in HFD-fed mice. This study reports a physiological signal that stimulates nuclear export of RIP140 in adipocytes and provides evidence for a strategy using selective ET(A) antagonist to treat obesity-induced insulin resistance and, possibly, other metabolic disorders.
Collapse
Affiliation(s)
- Ping-Chih Ho
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455-0217, USA
| | | | | | | | | |
Collapse
|
22
|
Pernow J, Shemyakin A, Böhm F. New perspectives on endothelin-1 in atherosclerosis and diabetes mellitus. Life Sci 2012; 91:507-16. [PMID: 22483688 DOI: 10.1016/j.lfs.2012.03.029] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/20/2012] [Accepted: 03/12/2012] [Indexed: 11/26/2022]
Abstract
Endothelin-1 (ET-1) is a vasoconstrictor, proinflammatory and proliferative endothelial cell-derived peptide that is of significant importance in the regulation of vascular function. It is involved in the development of endothelial dysfunction including important interactions with nitric oxide. The expression and functional effects of ET-1 and its receptors are markedly altered during development of cardiovascular disease. Increased production of ET-1 and its receptors mediate many pathophysiological events contributing to the development of atherosclerosis and vascular complications in diabetes mellitus. The present review focuses on the pathophysiological role of ET-1 and the potential importance of ET receptors as a therapeutic target for treatment of these conditions.
Collapse
Affiliation(s)
- John Pernow
- Karolinska Institutet, Cardiology Unit, Department of Medicine, Karolinska University Hospital, 171 76 Stockholm, Sweden.
| | | | | |
Collapse
|
23
|
Synergistic induction of interleukin-6 expression by endothelin-1 and cyclic AMP in adipocytes. Int J Obes (Lond) 2012; 37:197-203. [PMID: 22290536 DOI: 10.1038/ijo.2012.11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND We have demonstrated previously that endothelin-1 (ET-1) may stimulate interleukin-6 (IL-6) release from 3T3-L1 adipocytes. In this study, we further examined the combined effect of ET-1 and cyclic adenosine monophosphate (cAMP) on IL-6 release. METHODS IL-6 release was measured by enzyme-linked immuosorbent assay. Reverse transcriptase-PCR and real-time PCR analyses were used to determine cellular mRNA levels. A luciferase reporter driven by promoter (-1310/+198) of mouse IL-6 gene was transfected into 3T3-L1 adipocytes to monitor IL-6 transcription. RESULTS ET-1 and cAMP induced IL-6 release in a synergistic manner that can be attributed to their synergistic induction of IL-6 gene expression, as evidenced by IL-6 mRNA analysis and the IL-6 promoter reporter assay. Both ET(A) and ET(B) receptors seem to be involved. In addition, enhanced IL-6 promoter activity can be similarly induced by ET-1 and catecholamines (epinephrine and norepinephrine). The cooperative interaction between ET-1 and cAMP on IL-6 expression seems distinctive, as no other proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and IL-1β, are similarly affected. In fact, cAMP inhibited ET-1-stimulated TNF-α and IL-1β expressions in adipocytes. Furthermore, injection of mice with epinephrine and ET-1 induced a tremendously synergistic increase in serum IL-6 levels. Nevertheless, whereas cAMP induced IL-6 expression in RAW264.7 mouse macrophages, ET-1 had no effect on either the basal or the cAMP-induced IL-6 expression. CONCLUSION ET-1 and epinephrine may boost plasma IL-6 levels in mice in a synergistic manner, probably through their synergistic induction of IL-6 expression in adipocytes. SIGNIFICANCE This study should provide a new perspective for treating IL-6-related diseases, especially those accompanied with elevated ET-1 and catecholamine levels.
Collapse
|
24
|
Li Q, Hosaka T, Shikama Y, Bando Y, Kosugi C, Kataoka N, Nakaya Y, Funaki M. Heparin-binding EGF-like growth factor (HB-EGF) mediates 5-HT-induced insulin resistance through activation of EGF receptor-ERK1/2-mTOR pathway. Endocrinology 2012; 153:56-68. [PMID: 22028447 DOI: 10.1210/en.2011-1418] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although an inverse correlation between insulin sensitivity and the level of Gq/11-coupled receptor agonists, such as endothelin-1, thrombin, and 5-hydroxytryptamine (5-HT), has been reported, its precise mechanism remains unclear. In this report, we provide evidence that 5-HT induced production of heparin-binding epidermal growth factor-like growth factor (HB-EGF) and caused insulin resistance in 3T3-L1 adipocytes, primary adipocytes, and C2C12 myotubes. In 3T3-L1 adipocytes, 5-HT stimulated HB-EGF production by promoting metalloproteinase-dependent shedding of transmembrane protein pro-HB-EGF. HB-EGF then bound and tyrosine-phosphorylated EGF receptors, which activated the mammalian target of rapamycin pathway through ERK1/2 phosphorylation. Mammalian target of rapamycin activation caused serine phosphorylation of insulin receptor substrate-1, which attenuated insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1 and glucose uptake. Pharmacological inhibition of either Gq/11-coupled receptors or metalloproteinases, as well as either inhibition or knockdown of HB-EGF or Gαq/11, restored insulin signal transduction impaired by 5-HT. Inhibition of metalloproteinase activity also abolished HB-EGF production and subsequent EGF receptor activation by other Gq/11-coupled receptor agonists known to cause insulin resistance, such as endothelin-1 and thrombin. These results suggest that transactivation of the EGF receptor through HB-EGF processing plays a pivotal role in 5-HT-induced insulin resistance.
Collapse
Affiliation(s)
- Qinkai Li
- The Clinical Research Center for Diabetes, Tokushima University Hospital, 2-50-1 Kuramoto-cho, Tokushima 770-8503, Japan
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Bussey CT, Kolka CM, Rattigan S, Richards SM. Adiponectin opposes endothelin-1-mediated vasoconstriction in the perfused rat hindlimb. Am J Physiol Heart Circ Physiol 2011; 301:H79-86. [PMID: 21515669 DOI: 10.1152/ajpheart.00864.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent studies have shown that adiponectin is able to increase nitric oxide (NO) production by the endothelium and relax preconstricted isolated aortic rings, suggesting that adiponectin may act as a vasodilator. Endothelin-1 (ET-1) is a potent vasoconstrictor, elevated levels of which are associated with obesity, type 2 diabetes, hypertension, and cardiovascular disease. We hypothesized that adiponectin has NO-dependent vascular actions opposing the vasoconstrictor actions of ET-1. We studied the vascular and metabolic effects of a physiological concentration of adiponectin (6.5 μg/ml) on hooded Wistar rats in the constant-flow pump-perfused rat hindlimb. Adiponectin alone had no observable vascular activity; however, adiponectin pretreatment and coinfusion inhibited the increase in perfusion pressure and associated metabolic stimulation caused by low-dose (1 nM) ET-1. Adiponectin was not able to oppose vasoconstriction when infusion was commenced after ET-1. This is in contrast to the NO donor sodium nitroprusside, which significantly reduced the pressure due to established ET-1 vasoconstriction, suggesting dissociation of the actions of adiponectin and NO. In addition, adiponectin had no effect on vasoconstriction caused by either high-dose (20 nM) ET-1 or low-dose (50 nM) norepinephrine. Our findings suggest that adiponectin has specific, apparently NO-independent, vascular activity to oppose the vasoconstrictor effects of ET-1. The hemodynamic actions of adiponectin may be an important aspect of its insulin-sensitizing ability by regulating access of insulin and glucose to myocytes. Imbalance in the relationship between adiponectin and ET-1 in obesity may contribute to the development of insulin resistance and cardiovascular disease.
Collapse
Affiliation(s)
- Carol T Bussey
- Menzies Research Institute, Medical Science 1 Bldg., Private Bag 23, Hobart, Tasmania, Australia 7000
| | | | | | | |
Collapse
|
26
|
Kao YS, Fong JC. A novel cross-talk between endothelin-1 and cyclic AMP signaling pathways in the regulation of GLUT1 transcription in 3T3-L1 adipocytes. Cell Signal 2011; 23:901-10. [PMID: 21262356 DOI: 10.1016/j.cellsig.2011.01.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/14/2011] [Indexed: 01/04/2023]
Abstract
We showed previously that chronic exposure to both endothelin-1 (ET-1) and cAMP resulted in a synergistic increase in Glut1 transcription in 3T3-L1 adipocytes via a protein kinase C (PKC)-dependent mechanism. In the present study, we further examined the molecular mechanism involved. Employing transient transfections with Glut1 promoter/enhancer -luciferase reporter and several dominant negative or constitutively active PKC mutants, we identified PKCε as the responsible PKC. Investigation with deletion and mutation mutants of the promoter/enhancer reporter suggested that Sp1, CREB and AP-1 responsive elements on enhancer 2 were involved. Furthermore, chromatin immunoprecipitation and co-immunoprecipitation analysis were applied to characterize the interactions between these transcription factors and their bindings to enhancer 2 in vivo. The results indicate that there are both negative and positive interactions between ET-1 and cAMP signaling pathways. On the one hand, cAMP inhibits ET-1 induced NF-κB activation required for ET-1-stimulated Glut1 transcription; on the other hand, cAMP, via sustained CREB phosphorylation, may activate AP-1 and cooperate with ET-1-activated PKCε to enhance Sp1 expression and consequently to generate a stable enhancer 2-bound Sp1/pCREB/AP-1 complex, which can strongly facilitate Glut1 transcription more than the additive effect of ET-1 and cAMP alone.
Collapse
Affiliation(s)
- Ying-Shiun Kao
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, ROC
| | | |
Collapse
|
27
|
Chien Y, Lai YH, Kwok CF, Ho LT. Endothelin-1 suppresses long-chain fatty acid uptake and glucose uptake via distinct mechanisms in 3T3-L1 adipocytes. Obesity (Silver Spring) 2011; 19:6-12. [PMID: 20559307 DOI: 10.1038/oby.2010.124] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Endothelin-1 (ET-1) has been demonstrated to induce insulin resistance (IR) and lipolysis, raising the possibility that ET-1 may also contribute to the elevated fatty acid levels in IR-associated comorbidities. We attempted to evaluate whether ET-1 also affects the long-chain fatty acid (LCFA) utilization in 3T3-L1 adipocytes. The effects of chronic ET-1 exposure on basal and insulin-stimulated LCFA uptake, and LCFA uptake kinetics were examined in 3T3-L1 adipocytes. Chronic exposure to ET-1 induced IR and suppressed basal and insulin-stimulated LCFA uptake. Given that insulin acutely stimulates LCFA uptake, there was dramatically similar trend of dose-response curves for ET-1-suppressed LCFA uptake, and also similar corresponding IC₅₀ values, between basal and insulin-stimulated states, reflecting that ET-1 predominantly suppresses basal LCFA uptake. Results of LCFA kinetics, western blots, and CD36 inhibition using sulfosuccinimidyl oleate (SSO) revealed that suppression of LCFA uptake by ET-1 is associated with downregulation of CD36. ET type A receptor (ET(A)R) antagonist BQ-610 reversed the IR induction and the ET-1-suppressed LCFA uptake. Exogenous replenishment of phosphatidylinositol (PI) 4, 5-bisphosphate (PIP₂) prevented IR induction, but not the suppression of LCFA uptake by ET-1. Pharmacological inhibition of the activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) completely blocked the ET-1-suppressed LCFA uptake. Serving as an inducer of IR, ET-1 also chronically suppresses LCFA uptake via PIP₂-independent and ERK-dependent pathway. The interplay between impaired glucose disposal and diminished LCFA utilization, induced by ET-1, could worsen the dysregulation of adipose metabolism and energy homeostasis in insulin-resistant states.
Collapse
Affiliation(s)
- Yueh Chien
- Institutes of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | | | | | | |
Collapse
|
28
|
Fujita H, Hatakeyama H, Watanabe TM, Sato M, Higuchi H, Kanzaki M. Identification of three distinct functional sites of insulin-mediated GLUT4 trafficking in adipocytes using quantitative single molecule imaging. Mol Biol Cell 2010; 21:2721-31. [PMID: 20519436 PMCID: PMC2912357 DOI: 10.1091/mbc.e10-01-0029] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Insulin stimulation of glucose uptake is achieved by redistribution of insulin-responsive glucose transporters, GLUT4, from intracellular storage compartment(s) to the plasma membrane in adipocytes and muscle cells. Although GLUT4 translocation has been investigated using various approaches, GLUT4 trafficking properties within the cell are largely unknown. Our novel method allows direct analysis of intracellular GLUT4 dynamics at the single molecule level by using Quantum dot technology, quantitatively establishing the behavioral nature of GLUT4. Our data demonstrate the predominant mechanism for intracellular GLUT4 sequestration in the basal state to be "static retention" in fully differentiated 3T3L1 adipocytes. We also directly defined three distinct insulin-stimulated GLUT4 trafficking processes: 1) release from the putative GLUT4 anchoring system in storage compartment(s), 2) the speed at which transport GLUT4-containing vesicles move, and 3) the tethering/docking steps at the plasma membrane. Intriguingly, insulin-induced GLUT4 liberation from its static state appeared to be abolished by either pretreatment with an inhibitor of phosphatidylinositol 3-kinase or overexpression of a dominant-interfering AS160 mutant (AS160/T642A). In addition, our novel approach revealed the possibility that, in certain insulin-resistant states, derangements in GLUT4 behavior can impair insulin-responsive GLUT4 translocation.
Collapse
Affiliation(s)
- Hideaki Fujita
- Tohoku University Biomedical Engineering Research Organization, Sendai, Miyagi, 980-8575, Japan
| | | | | | | | | | | |
Collapse
|
29
|
Shemyakin A, Salehzadeh F, Böhm F, Al-Khalili L, Gonon A, Wagner H, Efendic S, Krook A, Pernow J. Regulation of glucose uptake by endothelin-1 in human skeletal muscle in vivo and in vitro. J Clin Endocrinol Metab 2010; 95:2359-66. [PMID: 20207830 DOI: 10.1210/jc.2009-1506] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CONTEXT Expression of the vasoconstrictor and proinflammatory peptide endothelin (ET)-1 is increased in insulin-resistant (IR) subjects. OBJECTIVE The aim of this study was to investigate whether ET-1 regulates skeletal muscle glucose uptake in IR subjects in vivo and in cultured human skeletal muscle cells. DESIGN AND PARTICIPANTS Eleven subjects participated in three protocols using brachial artery infusion of: A) BQ123 (10 nmol/min) and BQ788 (10 nmol/min) (ET(A) and ET(B) receptor antagonist, respectively), followed by coinfusion with insulin (0.05 mU/kg/min); B) insulin alone; and C) insulin followed by coinfusion with ET-1 (20 pmol/min). MAIN OUTCOME MEASURES Forearm blood flow (FBF) and forearm glucose uptake (FGU) were determined. Glucose uptake and molecular signaling were determined in cultured skeletal muscle cells. RESULTS ET(A)/ET(B) receptor blockade increased FGU by 63% (P < 0.05). Coadministration of insulin caused a further 2-fold increase in FGU (P < 0.001). ET(A)/ET(B) receptor blockade combined with insulin resulted in greater FGU than insulin infusion alone (P < 0.005). ET(A)/ET(B) receptor blockade increased FBF by 30% (P < 0.05), with a further 16% increase (P < 0.01) during insulin coinfusion. ET-1 decreased basal FBF by 35% without affecting FGU. ET-1 impaired basal and insulin-stimulated glucose uptake in cultured muscle cells (P < 0.01) via an effect that was prevented by ET(A)/ET(B) receptor blockade. CONCLUSION ET(A)/ET(B) receptor blockade enhances basal and insulin-stimulated glucose uptake in IR subjects. ET-1 directly impairs glucose uptake in skeletal muscle cells via a receptor-dependent mechanism. These data suggest that ET-1 regulates glucose metabolism via receptor-dependent mechanisms in IR subjects.
Collapse
Affiliation(s)
- Alexey Shemyakin
- Karolinska University Hospital Solna, Center for Molecular Medicine, L8:03, S-171 76, Stockholm, Sweden.
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Reiter CEN, Kim JA, Quon MJ. Green tea polyphenol epigallocatechin gallate reduces endothelin-1 expression and secretion in vascular endothelial cells: roles for AMP-activated protein kinase, Akt, and FOXO1. Endocrinology 2010; 151:103-14. [PMID: 19887561 PMCID: PMC2803145 DOI: 10.1210/en.2009-0997] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Epigallocatechin gallate (EGCG), a green tea polyphenol, promotes vasodilation by phosphatidylinositol 3-kinase-dependent activation of Akt and endothelial nitric oxide synthase to stimulate production of nitric oxide. Reduction in endothelin-1 (ET-1) synthesis may also increase bioavailability of nitric oxide. We hypothesized that the phosphatidylinositol 3-kinase-dependent transcription factor FOXO1 may mediate effects of EGCG to regulate expression of ET-1 in endothelial cells. EGCG treatment (10 microm, 8 h) of human aortic endothelial cells reduced expression of ET-1 mRNA, protein, and ET-1 secretion. We identified a putative FOXO binding domain in the human ET-1 promoter 51 bp upstream from the transcription start site. Trans-activation of a human ET-1 (hET-1) promoter luciferase reporter was enhanced by coexpression of a constitutively nuclear FOXO1 mutant, whereas expression of a mutant FOXO1 with disrupted DNA binding domain did not trans-activate the hET-1 promoter. Disrupting the hET-1 putative FOXO binding domain by site-directed mutagenesis ablated promoter activity in response to overexpression of wild-type FOXO1. EGCG stimulated time-dependent phosphorylation of Akt (S(473)), FOXO1 (at Akt phosphorylation site T(24)), and AMP-activated protein kinase alpha (AMPK alpha) (T(172)). EGCG-induced nuclear exclusion of FOXO1, FOXO1 binding to the hET-1 promoter, and reduction of ET-1 expression was partially inhibited by the AMPK inhibitor Compound C. Basal ET-1 protein expression was enhanced by short interfering RNA knock-down of Akt and reduced by short interfering RNA knock-down of FOXO1 or adenovirus-mediated expression of dominant-negative Foxo1. We conclude that EGCG decreases ET-1 expression and secretion from endothelial cells, in part, via Akt- and AMPK-stimulated FOXO1 regulation of the ET-1 promoter. These findings may be relevant to beneficial cardiovascular actions of green tea.
Collapse
Affiliation(s)
- Chad E N Reiter
- Diabetes Unit, National Center for Complementary and Alternative Medicine, National Institutes of Health, 9 Memorial Drive, Bethesda, Maryland 20892-0920, USA
| | | | | |
Collapse
|
31
|
Katakam PVG, Domoki F, Lenti L, Gáspár T, Institoris A, Snipes JA, Busija DW. Cerebrovascular responses to insulin in rats. J Cereb Blood Flow Metab 2009; 29:1955-67. [PMID: 19724283 PMCID: PMC2814524 DOI: 10.1038/jcbfm.2009.177] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Effects of insulin on cerebral arteries have never been examined. Therefore, we determined cerebrovascular actions of insulin in rats. Both PCR and immunoblot studies identified insulin receptor expression in cerebral arteries and in cultured cerebral microvascular endothelial cells (CMVECs). Diameter measurements (% change) of isolated rat cerebral arteries showed a biphasic dose response to insulin with an initial vasoconstriction at 0.1 ng/mL (-9.7%+/-1.6%), followed by vasodilation at 1 to 100 ng/mL (31.9%+/-1.4%). Insulin also increased cortical blood flow in vivo (30%+/-8% at 120 ng/mL) when applied topically. Removal of reactive oxygen species (ROS) abolished the vasoconstriction to insulin. Endothelial denudation, inhibition of K(+) channels, and nitric oxide (NO) synthase, all diminished insulin-induced vasodilation. Inhibition of cytochrome P450 enhanced vasodilation in endothelium-intact arteries, but promoted vasoconstriction after endothelial denudation. Inhibition of cyclooxygenase abolished vasoconstriction and enhanced vasodilation to insulin in all arteries. Inhibition of endothelin type A receptors enhanced vasodilation, whereas endothelin type B receptor blockade diminished vasodilation. Insulin treatment in vitro increased Akt phosphorylation in cerebral arteries and CMVECs. Fluorescence studies of CMVECs showed that insulin increased intracellular calcium and enhanced the generation of NO and ROS. Thus, cerebrovascular responses to insulin were mediated by complex mechanisms originating in both the endothelium and smooth muscle.
Collapse
|
32
|
Abstract
Insulin is a vascular hormone, able to influence vascular cell responses. In this review, we consider the insulin actions on vascular endothelium and on vascular smooth muscle cells (VSMC) both in physiological conditions and in the presence of insulin resistance. In particular, we focus the relationships between activation of insulin signalling pathways of phosphatidylinositol-3 kinase (PI3-K) and mitogen-activated protein kinase (MAPK) and the different vascular actions of insulin, with a particular attention to the insulin ability to activate the pathway nitric oxide (NO)/cyclic GMP/PKG via PI3-K, owing to the peculiar relevance of NO in vascular biology. We also discuss the insulin actions mediated by the MAPK pathway (such as endothelin-1 synthesis and secretion and VSMC proliferation and migration) and by the interactions between the two pathways, both in insulin-sensitive and in insulin-resistant states. Finally, we consider the influence of free fatty acids, cytokines and endothelin on vascular insulin resistance.
Collapse
Affiliation(s)
- Giovanni Anfossi
- Internal Medicine University Unit, San Luigi Gonzaga Faculty of Medicine and Department of Clinical and Biological Sciences, Turin University, San Luigi Gonzaga Hospital, 10043 Orbassano, Turin, Italy
| | | | | | | |
Collapse
|
33
|
Chang E, Donkin SS, Teegarden D. Parathyroid hormone suppresses insulin signaling in adipocytes. Mol Cell Endocrinol 2009; 307:77-82. [PMID: 19524129 PMCID: PMC2714196 DOI: 10.1016/j.mce.2009.03.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 03/16/2009] [Accepted: 03/17/2009] [Indexed: 10/20/2022]
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.
Collapse
Affiliation(s)
| | | | - Dorothy Teegarden
- Corresponding Author: Dorothy Teegarden, PhD, 700 W. State St., West Lafayette IN 47907, 765-494-8246, FAX: 765-494-0906,
| |
Collapse
|
34
|
Abstract
Insulin signaling at target tissues is essential for growth and development and for normal homeostasis of glucose, fat, and protein metabolism. Control over this process is therefore tightly regulated. It can be achieved by a negative feedback control mechanism whereby downstream components inhibit upstream elements along the insulin-signaling pathway (autoregulation) or by signals from apparently unrelated pathways that inhibit insulin signaling thus leading to insulin resistance. Phosphorylation of insulin receptor substrate (IRS) proteins on serine residues has emerged as a key step in these control processes under both physiological and pathological conditions. The list of IRS kinases implicated in the development of insulin resistance is growing rapidly, concomitant with the list of potential Ser/Thr phosphorylation sites in IRS proteins. Here, we review a range of conditions that activate IRS kinases to phosphorylate IRS proteins on "hot spot" domains. The flexibility vs. specificity features of this reaction is discussed and its characteristic as an "array" phosphorylation is suggested. Finally, its implications on insulin signaling, insulin resistance and type 2 diabetes, an emerging epidemic of the 21st century are outlined.
Collapse
Affiliation(s)
- Sigalit Boura-Halfon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100 Israel
| | | |
Collapse
|
35
|
Boura-Halfon S, Zick Y. Serine kinases of insulin receptor substrate proteins. VITAMINS AND HORMONES 2009; 80:313-49. [PMID: 19251043 DOI: 10.1016/s0083-6729(08)00612-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Signaling of insulin and insulin-like growth factor-I (IGF-1) at target tissues is essential for growth, development and for normal homeostasis of glucose, fat, and protein metabolism. Control over this process is therefore tightly regulated. It can be achieved by a negative-feedback control mechanism, whereby downstream components inhibit upstream elements along the insulin and IGF-1 signaling pathway or by signals from other pathways that inhibit insulin/IGF-1 signaling thus leading to insulin/IGF-1 resistance. Phosphorylation of insulin receptor substrates (IRS) proteins on serine residues has emerged as a key step in these control processes both under physiological and pathological conditions. The list of IRS kinases is growing rapidly, concomitant with the list of potential Ser/Thr phosphorylation sites in IRS proteins. Here we review a range of conditions that activate IRS kinases to phosphorylate IRS proteins on selected domains. The specificity of this reaction is discussed and its characteristic as an "array" phosphorylation is suggested. Finally, its implications on insulin/IGF-1 signaling, insulin/IGF-1 resistance and diabetes, an emerging epidemic of the twenty-first century are outlined.
Collapse
Affiliation(s)
- Sigalit Boura-Halfon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | | |
Collapse
|
36
|
Chai SP, Chang YN, Fong JC. Endothelin-1 stimulates interleukin-6 secretion from 3T3-L1 adipocytes. Biochim Biophys Acta Gen Subj 2008; 1790:213-8. [PMID: 19162127 DOI: 10.1016/j.bbagen.2008.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/14/2008] [Accepted: 12/18/2008] [Indexed: 11/24/2022]
Abstract
BACKGROUND Since both endothelin-1 (ET-1) and interleukin-6 (IL-6) may induce insulin resistance and adipose tissue is a major contributor of circulating IL-6, we examined the effects of ET-1 on IL-6 secretion from 3T3-L1 adipocytes. METHODS IL-6 release was measured by ELISA. RT-PCR and real-time PCR analyses were used to determine cellular IL-6 mRNA levels. A luciferase reporter driven by promoter (-1310/+198) of mouse IL-6 gene was transfected into 3T3-L1 adipocytes to monitor IL-6 transcription. RESULTS Treatment of adipocytes with ET-1 dose- and time-dependently increased IL-6 secretion. The stimulatory effect of ET-1 on IL-6 secretion was abolished by actinomycin D and ET-1 induced an increase in IL-6 mRNA levels. ET-1 was able to enhance the IL-6 promoter activity and its stimulatory effect was inhibited by GF109203X, U0126, salicylate, dominant negative CREB and mithramycin A. Thus it appears that ET-1 may stimulate IL-6 secretion mainly through an enhanced IL-6 transcription, by a mechanism involving both protein kinase C and p42/p44 mitogen-activated protein kinase, and probably downstream NF-kappaB, CREB and Sp1 transcription factors. GENERAL SIGNIFICANCE This study demonstrates that ET-1 is able to increase IL-6 secretion from adipocytes and raises the possibility that ET-1-induced insulin resistance may be mediated by IL-6.
Collapse
Affiliation(s)
- Shin-Pei Chai
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan
| | | | | |
Collapse
|
37
|
Elgebaly MM, Kelly A, Harris AK, Elewa H, Portik-Dobos V, Ketsawatsomkron P, Marrero M, Ergul A. Impaired insulin-mediated vasorelaxation in a nonobese model of type 2 diabetes: role of endothelin-1. Can J Physiol Pharmacol 2008; 86:358-64. [PMID: 18516099 DOI: 10.1139/y08-034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Insulin resistance involves decreased phosphorylation of insulin receptor substrate (IRS) proteins and (or) Akt. In the vasculature, modulated Akt phosphorylation may cause impaired vasorelaxation via decreased eNOS activation. Diet-induced insulin resistance enhances endothelin-1(ET-1)-mediated vasoconstriction and prevents vasodilatation to insulin. Presently, we evaluated insulin-mediated vascular relaxation, assessed molecular markers of the insulin signaling pathway, and determined the involvement of ET-1 in response to insulin by using selective ETA- or ETB-receptor blockade in a lean model of type 2 diabetes. Dose-response curves to insulin (0.01-100 ng/mL) were generated with wire myograph using thoracic aorta rings from control Wistar or diabetic Goto-Kakizaki (GK) rats (n=3-11). Maximal relaxation (Rmax) to insulin was significantly impaired and insulin sensitivity was decreased in the GK group. Preincubation with 1 micromol/L BQ-123 or BQ-788 for ETA- and ETB-receptor blockade, respectively, resulted in improved insulin sensitivity. Immunoblotting for native and phosphorylated Akt and IRS-1 revealed a decrease in Akt activation in the GK group. In vivo hyperinsulinemic euglycemic clamp studies showed decreased glucose utilization in GK rats, indicative of insulin resistance. These findings provide evidence that vascular insulin resistance occurs in a nonobese model of diabetes and that both ET receptor subtypes are involved in vascular relaxation to insulin.
Collapse
Affiliation(s)
- Mostafa M Elgebaly
- Program in Clinical and Experimental Therapeutics, University of Georgia College of Pharmacy, Augusta, GA 30912, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Kashyap SR, Belfort R, Cersosimo E, Lee S, Cusi K. Chronic Low-Dose Lipid Infusion in Healthy Patients Induces Markers of Endothelial Activation Independent of Its Metabolic Effects. ACTA ACUST UNITED AC 2008; 3:141-6. [DOI: 10.1111/j.1559-4572.2008.00013.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
39
|
Kao YS, Fong JC. Endothelin-1 induces glut1 transcription through enhanced interaction between Sp1 and NF-κB transcription factors. Cell Signal 2008; 20:771-8. [DOI: 10.1016/j.cellsig.2007.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Accepted: 12/17/2007] [Indexed: 01/04/2023]
|
40
|
Endothelin-1 induction of Glut1 transcription in 3T3-L1 adipocytes involves distinct PKCε- and p42/p44 MAPK-dependent pathways. Biochim Biophys Acta Gen Subj 2008; 1780:154-9. [DOI: 10.1016/j.bbagen.2007.11.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 11/11/2007] [Accepted: 11/27/2007] [Indexed: 01/04/2023]
|
41
|
van Harmelen V, Eriksson A, Aström G, Wåhlén K, Näslund E, Karpe F, Frayn K, Olsson T, Andersson J, Rydén M, Arner P. Vascular peptide endothelin-1 links fat accumulation with alterations of visceral adipocyte lipolysis. Diabetes 2008; 57:378-86. [PMID: 18025413 DOI: 10.2337/db07-0893] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Visceral obesity increases risk of insulin resistance and type 2 diabetes. This may partly be due to a region-specific resistance to insulin's antilipolytic effect in visceral adipocytes. We investigated whether adipose tissue releases the vascular peptide endothelin-1 (ET-1) and whether ET-1 could account for regional differences in lipolysis. RESEARCH DESIGN AND METHODS One group consisted of eleven obese and eleven nonobese subjects in whom ET-1 levels were compared between abdominal subcutaneous and arterialized blood samples. A second group included subjects undergoing anti-obesity surgery. Abdominal subcutaneous and visceral adipose tissues were obtained to study the effect of ET-1 on differentiated adipocytes regarding lipolysis and gene and protein expression. RESULTS Adipose tissue had a marked net release of ET-1 in vivo, which was 2.5-fold increased in obesity. In adipocytes treated with ET-1, the antilipolytic effect of insulin was attenuated in visceral but not in subcutaneous adipocytes, which could not be explained by effects of ET-1 on adipocyte differentiation. ET-1 decreased the expression of insulin receptor, insulin receptor substrate-1 and phosphodiesterase-3B and increased the expression of endothelin receptor-B (ET(B)R) in visceral but not in subcutaneous adipocytes. These effects were mediated via ET(B)R with signals through protein kinase C and calmodulin pathways. The effect of ET-1 could be mimicked by knockdown of IRS-1. CONCLUSIONS ET-1 is released from human adipose tissue and links fat accumulation to insulin resistance. It selectively counteracts insulin inhibition of visceral adipocyte lipolysis via ET(B)R signaling pathways, which affect multiple steps in insulin signaling.
Collapse
Affiliation(s)
- Vanessa van Harmelen
- Karolinska Institutet, Department of Medicine, M63, Karolinska University Hospital, Huddinge, SE-141 86 Stockholm, Sweden
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Kawamata Y, Imamura T, Babendure JL, Lu JC, Yoshizaki T, Olefsky JM. Tumor necrosis factor receptor-1 can function through a G alpha q/11-beta-arrestin-1 signaling complex. J Biol Chem 2007; 282:28549-28556. [PMID: 17664271 DOI: 10.1074/jbc.m705869200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Tumor necrosis factor-alpha (TNFalpha) is a proinflammatory cytokine secreted from macrophages and adipocytes. It is well known that chronic TNFalpha exposure can lead to insulin resistance both in vitro and in vivo and that elevated blood levels of TNFalpha are observed in obese and/or diabetic individuals. TNFalpha has many acute biologic effects, mediated by a complex intracellular signaling pathway. In these studies we have identified new G-protein signaling components to this pathway in 3T3-L1 adipocytes. We found that beta-arrestin-1 is associated with TRAF2 (TNF receptor-associated factor 2), an adaptor protein of TNF receptors, and that TNFalpha acutely stimulates tyrosine phosphorylation of G alpha(q/11) with an increase in G alpha(q/11) activity. Small interfering RNA-mediated knockdown of beta-arrestin-1 inhibits TNFalpha-induced tyrosine phosphorylation of G alpha(q/11) by interruption of Src kinase activation. TNFalpha stimulates lipolysis in 3T3-L1 adipocytes, and beta-arrestin-1 knockdown blocks the effects of TNFalpha to stimulate ERK activation and glycerol release. TNFalpha also led to activation of JNK with increased expression of the proinflammatory gene, monocyte chemoattractant protein-1 and matrix metalloproteinase 3, and beta-arrestin-1 knockdown inhibited both of these effects. Taken together these results reveal novel elements of TNFalpha action; 1) the trimeric G-protein component G alpha(q/11) and the adapter protein beta-arrestin-1 can function as signaling molecules in the TNFalpha action cascade; 2) beta-arrestin-1 can couple TNFalpha stimulation to ERK activation and lipolysis; 3) beta-arrestin-1 and G alpha(q/11) can mediate TNFalpha-induced phosphatidylinositol 3-kinase activation and inflammatory gene expression.
Collapse
Affiliation(s)
- Yuji Kawamata
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673
| | - Takeshi Imamura
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673
| | - Jennie L Babendure
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673
| | - Juu-Chin Lu
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673
| | - Takeshi Yoshizaki
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673
| | - Jerrold M Olefsky
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673.
| |
Collapse
|
43
|
Liao W, Nguyen MTA, Yoshizaki T, Favelyukis S, Patsouris D, Imamura T, Verma IM, Olefsky JM. Suppression of PPAR-gamma attenuates insulin-stimulated glucose uptake by affecting both GLUT1 and GLUT4 in 3T3-L1 adipocytes. Am J Physiol Endocrinol Metab 2007; 293:E219-27. [PMID: 17389706 DOI: 10.1152/ajpendo.00695.2006] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays a critical role in regulating insulin sensitivity and glucose homeostasis. In this study, we identified highly efficient small interfering RNA (siRNA) sequences and used lentiviral short hairpin RNA and electroporation of siRNAs to deplete PPAR-gamma from 3T3-L1 adipocytes to elucidate its role in adipogenesis and insulin signaling. We show that PPAR-gamma knockdown prevented adipocyte differentiation but was not required for maintenance of the adipocyte differentiation state after the cells had undergone adipogenesis. We further demonstrate that PPAR-gamma suppression reduced insulin-stimulated glucose uptake without affecting the early insulin signaling steps in the adipocytes. Using dual siRNA strategies, we show that this effect of PPAR-gamma deletion was mediated by both GLUT4 and GLUT1. Interestingly, PPAR-gamma-depleted cells displayed enhanced inflammatory responses to TNF-alpha stimulation, consistent with a chronic anti-inflammatory effect of endogenous PPAR-gamma. In summary, 1) PPAR-gamma is essential for the process of adipocyte differentiation but is less necessary for maintenance of the differentiated state, 2) PPAR-gamma supports normal insulin-stimulated glucose transport, and 3) endogenous PPAR-gamma may play a role in suppression of the inflammatory pathway in 3T3-L1 cells.
Collapse
Affiliation(s)
- Wei Liao
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA 92093, USA
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Abstract
The dissection of mechanisms that regulate glucose transport by insulin has revealed an intricate network of signaling molecules scattered from the insulin receptor to the intracellular glucose transporter GLUT4. It is also appreciated that some insulin receptor signals jaunt in different directions to regulate events essential for the efficient redistribution of GLUT4 to the plasma membrane. Moreover key assists in the process appear to be arranged by membrane lipids and cytoskeletal proteins. Following current considerations of insulin signals regulating GLUT4, this review will focus on in vitro and in vivo evidence that supports an essential role for phosphoinositides and actin filaments in the control of glucose transport. The discussion will visit recent cell culture, whole animal, and human data highlighting membrane and cytoskeletal aspects of insulin resistance.
Collapse
Affiliation(s)
- Joseph T Brozinick
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, USA.
| | | | | |
Collapse
|
45
|
Abstract
The normal action of insulin to vasodilate and redistribute blood flow in support of skeletal muscle metabolism is impaired in insulin-resistant states. Increased endogenous endothelin contributes to endothelial dysfunction in obesity and diabetes. Here, we test the hypothesis that increased endogenous endothelin action also contributes to skeletal muscle insulin resistance via impairments in insulin-stimulated vasodilation. We studied nine lean and seven obese humans, measuring the metabolic and hemodynamic effects of insulin (300 mU . m(-2) . min(-1)) alone and during femoral artery infusion of BQ123 (an antagonist of type A endothelin receptors, 1 micromol/min). Endothelin antagonism augmented skeletal muscle responses to insulin in obese subjects through changes in both leg blood flow (LBF) and glucose extraction. Insulin-stimulated LBF was significantly increased in obese subjects only. These changes, combined with differential effects on glucose extraction, resulted in augmented insulin-stimulated leg glucose uptake in obese subjects (54.7 +/- 5.7 vs. 107.4 +/- 18.9 mg/min with BQ123), with no change in lean subjects (103.7 +/- 11.4 vs. 88.9 +/- 16.3, P = 0.04 comparing BQ123 across groups). BQ123 allowed augmented leg glucose extraction in obese subjects even in the face of NOS antagonism. These findings suggest that increased endogenous endothelin action contributes to insulin resistance in skeletal muscle of obese humans, likely through both vascular and tissue effects.
Collapse
Affiliation(s)
- Amale Lteif
- Division of Endocrinology and Metabolism, Department of Medicine, Indiana University School of Medicine, CL459, 541 North Clinical Drive, Indianapolis, IN 46202, USA
| | | | | | | |
Collapse
|
46
|
Sarafidis PA, Bakris GL. Review: Insulin and endothelin: an interplay contributing to hypertension development? J Clin Endocrinol Metab 2007; 92:379-85. [PMID: 17118997 DOI: 10.1210/jc.2006-1819] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
CONTEXT The aim of this article was to review the existing data on the interactions among insulin, insulin resistance, and endothelin and how those contribute to the development of hypertension in insulin-resistant states. EVIDENCE ACQUISITION A literature search of MEDLINE database was performed to identify English-language articles published during the last 20 yr. Search terms used were endothelin, insulin, insulin resistance, and hyperinsulinemia in combination with blood pressure and hypertension. Reference lists of retrieved articles were also evaluated for relevant information. EVIDENCE SYNTHESIS Several mechanisms connect insulin resistance and compensatory hyperinsulinemia with blood pressure elevation in the context of the metabolic syndrome, i.e. sodium retention, sympathetic activation, and impairment of endothelial nitric oxide production. Accumulating evidence suggests that activation of the endothelin system seems to be another important, yet less discussed, mechanism. In vitro studies have shown that insulin stimulates both endothelin-1 production and action on the vascular wall. In vivo, high levels of insulin result in increase in circulating endothelin-1 in healthy individuals, and this effect is also seen in insulin-resistant subjects, a relationship not observed with nitric oxide production. Moreover, endothelin receptor antagonism effectively reduces blood pressure in animal models of insulin resistance and hypertension. On the other hand, elevation of endothelin-1 levels can further increase insulin resistance, forming possibly a deleterious circle. CONCLUSIONS Endothelin-1 may play a crucial role in the pathogenesis of hypertension in insulin-resistant states. Future research should examine the potential of endothelin receptor antagonism to help blood pressure control in patients with insulin resistance.
Collapse
Affiliation(s)
- Pantelis A Sarafidis
- Hypertension/Clinical Research Center, Department of Preventive Medicine, Rush University Medical Center, 1700 West Van Buren, Suite 470, Chicago, Illinois 60612, USA.
| | | |
Collapse
|
47
|
Bhattacharya I, Ullrich A. Endothelin-1 inhibits adipogenesis: role of phosphorylation of Akt and ERK1/2. FEBS Lett 2006; 580:5765-71. [PMID: 17022980 DOI: 10.1016/j.febslet.2006.09.032] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 08/11/2006] [Accepted: 09/13/2006] [Indexed: 11/23/2022]
Abstract
In adipogenesis, growth factors play a crucial role. Using serum depleted condition, we studied the causal role of endothelin-1 (ET-1) and epidermal growth factor (EGF), separately or together, in adipocyte differentiation of 3T3-L1 cells. ET-1 stimulation caused an anti-adipogenic response and this effect was potentiated upon treatment with EGF. Co-treatment with EGF and ET-1 blocked the expression of C/EBPalpha and PPARgamma, the adipogenic markers. The inhibition of adipogenesis was preceded by a biphasic (early and late) attenuation of Akt phosphorylation. We suggest that treatment with ET-1 and EGF together induce a more potent anti-adipogenic response, involving increased Erk1/2 phosphorylation and biphasic attenuation of Akt phosphorylation.
Collapse
Affiliation(s)
- Indranil Bhattacharya
- Department of Molecular Biology, Max Planck Institute for Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | | |
Collapse
|
48
|
Strawbridge AB, Elmendorf JS. Endothelin-1 impairs glucose transporter trafficking via a membrane-based mechanism. J Cell Biochem 2006; 97:849-56. [PMID: 16240321 PMCID: PMC2409058 DOI: 10.1002/jcb.20687] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Endothelin-1 (ET-1) disrupts insulin-regulated glucose transporter GLUT4 trafficking. Since the negative consequence of chronic ET-1 exposure appears to be independent of signal disturbance along the insulin receptor substrate-1/phosphatidylinositol (PI) 3-kinase (PI3K)/Akt-2 pathway of insulin action, we tested if ET-1 altered GLUT4 regulation engaged by osmotic shock, a PI3K-independent stimulus that mimics insulin action. Regulation of GLUT4 by hyperosmotic stress was impaired by ET-1. Because of the mutual disruption of both insulin- and hyperosmolarity-stimulated GLUT4 translocation, we tested whether shared signaling and/or key phosphatidylinositol 4,5-bisphosphate (PIP2)-regulated cytoskeletal events of GLUT4 trafficking were targets of ET-1. Both insulin and hyperosmotic stress signaling to Cbl were impaired by ET-1. Also, plasma membrane PIP2 and cortical actin levels were reduced in cells exposed to ET-1. Exogenous PIP2, but not PI 3,4,5-bisphosphate, restored actin structure, Cbl activation, and GLUT4 translocation. These data show that ET-1-induced PIP2/actin disruption impairs GLUT4 trafficking elicited by insulin and hyperosmolarity. In addition to showing for the first time the important role of PIP2-regulated cytoskeletal events in GLUT4 regulation by stimuli other than insulin, these studies reveal a novel function of PIP2/actin structure in signal transduction.
Collapse
Affiliation(s)
- Andrew B. Strawbridge
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Center for Diabetes Research, Indianapolis, Indiana
| | - Jeffrey S. Elmendorf
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Center for Diabetes Research, Indianapolis, Indiana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Center for Diabetes Research, Indianapolis, Indiana
- *Correspondence to: Jeffrey S. Elmendorf, 635 Barnhill Drive, MS308A, Indianapolis, Indiana 46202., E-mail:
| |
Collapse
|
49
|
Abstract
Obesity and obstructive sleep apnea (OSA) often coexist. OSA has been linked to cardiovascular disease. Thus, OSA may contribute to the cardiovascular consequences of obesity. In this review, we explore clinical and pathophysiological interactions between obesity, cardiovascular disease and OSA. We discuss the mechanisms whereby OSA may contribute to hypertension, atherosclerosis, insulin resistance and atrial fibrillation associated with obesity, and emphasize the potential implications for understanding why only a subgroup of obese patients develop cardiovascular disease. Identification of the OSA-dependent and OSA-independent pathways in the cardiovascular pathophysiology of obesity may hold clinical and therapeutic promise.
Collapse
Affiliation(s)
- R Wolk
- Department of Medicine, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55902, USA
| | | |
Collapse
|
50
|
Liao W, Nguyen MTA, Imamura T, Singer O, Verma IM, Olefsky JM. Lentiviral short hairpin ribonucleic acid-mediated knockdown of GLUT4 in 3T3-L1 adipocytes. Endocrinology 2006; 147:2245-52. [PMID: 16497797 DOI: 10.1210/en.2005-1638] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adipose tissue is an important insulin target organ, and 3T3-L1 cells are a model cell line for adipocytes. In this study, we have used lentivirus-mediated short hairpin RNA (shRNA) for functional gene knockdown in 3T3-L1 adipocytes to assess the molecular mechanisms of insulin signaling. We chose to target GLUT4 to validate this approach. We showed that lentiviruses efficiently delivered transgenes and small interfering RNA (siRNA) into fully differentiated 3T3-L1 adipocytes. We established a strategy for identifying efficient siRNA sequences for gene knockdown by transfecting 293 cells with the target gene fluorescent fusion protein plasmid along with a plasmid that expresses shRNA. Using these methods, we identified highly efficient siGLUT4 sequences. We demonstrated that lentivirus-mediated shRNA against GLUT4 reduced endogenous GLUT4 expression to almost undetectable levels in 3T3-L1 adipocytes. Interestingly, insulin-stimulated glucose uptake was only reduced by 50-60%, suggesting that another glucose transporter mediates part of this effect. When siGLUT1 was introduced into GLUT4-deficient adipocytes, insulin-stimulated glucose uptake was essentially abolished, indicating that both GLUT4 and GLUT1 contribute to insulin-stimulated glucose transport in 3T3-L1 adipocytes. We also found that GLUT4 knockdown led to impaired insulin-responsive aminopeptidase protein expression that was dependent on whether GLUT4 was knocked down in the differentiating or differentiated stage. We further found that GLUT4 expression was not required for adipogenic differentiation but was necessary for full lipogenic capacity of differentiated adipocytes. These studies indicate that lentiviral shRNA constructs provide an excellent approach to deliver functional siRNAs into 3T3-L1 adipocytes for studying insulin signaling and adipocyte biology.
Collapse
Affiliation(s)
- Wei Liao
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, 92093, USA
| | | | | | | | | | | |
Collapse
|