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Targeting Adrenergic Receptors in Metabolic Therapies for Heart Failure. Int J Mol Sci 2021; 22:ijms22115783. [PMID: 34071350 PMCID: PMC8198887 DOI: 10.3390/ijms22115783] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 12/14/2022] Open
Abstract
The heart has a reduced capacity to generate sufficient energy when failing, resulting in an energy-starved condition with diminished functions. Studies have identified numerous changes in metabolic pathways in the failing heart that result in reduced oxidation of both glucose and fatty acid substrates, defects in mitochondrial functions and oxidative phosphorylation, and inefficient substrate utilization for the ATP that is produced. Recent early-phase clinical studies indicate that inhibitors of fatty acid oxidation and antioxidants that target the mitochondria may improve heart function during failure by increasing compensatory glucose oxidation. Adrenergic receptors (α1 and β) are a key sympathetic nervous system regulator that controls cardiac function. β-AR blockers are an established treatment for heart failure and α1A-AR agonists have potential therapeutic benefit. Besides regulating inotropy and chronotropy, α1- and β-adrenergic receptors also regulate metabolic functions in the heart that underlie many cardiac benefits. This review will highlight recent studies that describe how adrenergic receptor-mediated metabolic pathways may be able to restore cardiac energetics to non-failing levels that may offer promising therapeutic strategies.
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Perez DM. Current Developments on the Role of α 1-Adrenergic Receptors in Cognition, Cardioprotection, and Metabolism. Front Cell Dev Biol 2021; 9:652152. [PMID: 34113612 PMCID: PMC8185284 DOI: 10.3389/fcell.2021.652152] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/29/2021] [Indexed: 12/13/2022] Open
Abstract
The α1-adrenergic receptors (ARs) are G-protein coupled receptors that bind the endogenous catecholamines, norepinephrine, and epinephrine. They play a key role in the regulation of the sympathetic nervous system along with β and α2-AR family members. While all of the adrenergic receptors bind with similar affinity to the catecholamines, they can regulate different physiologies and pathophysiologies in the body because they couple to different G-proteins and signal transduction pathways, commonly in opposition to one another. While α1-AR subtypes (α1A, α1B, α1C) have long been known to be primary regulators of vascular smooth muscle contraction, blood pressure, and cardiac hypertrophy, their role in neurotransmission, improving cognition, protecting the heart during ischemia and failure, and regulating whole body and organ metabolism are not well known and are more recent developments. These advancements have been made possible through the development of transgenic and knockout mouse models and more selective ligands to advance their research. Here, we will review the recent literature to provide new insights into these physiological functions and possible use as a therapeutic target.
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Affiliation(s)
- Dianne M Perez
- The Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH, United States
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Papay RS, Perez DM. α 1-Adrenergic receptors increase glucose oxidation under normal and ischemic conditions in adult mouse cardiomyocytes. J Recept Signal Transduct Res 2020; 41:138-144. [PMID: 32757689 DOI: 10.1080/10799893.2020.1799291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The role of catecholamine receptors in cardiac energy metabolism is unknown. α1-adrenergic receptors (α1-ARs) have been identified to play a role in whole body metabolism but its role in cardiac energy metabolism has not been explored. We used freshly prepared primary adult mouse cardiomyocytes and incubated with either 14C-palmitate or 14C-glucose tracers to measure oxidation rates in the presence or absence of phenylephrine, an α1-AR agonist (with β and α2-AR blockers) under normal cell culture conditions. 14CO2 released was collected over a 10 min period in covered tissue culture plates using a 1 M hyamine hydroxide solution placed in well cups, counted by scintillation and converted into nmoles/hr. We found that phenylephrine stimulated glucose oxidation but not fatty acid oxidation in adult primary cardiomyocytes. α1-AR stimulated glucose oxidation was blocked by the AMPK inhibitor, dorsomorphin dihydrochloride, and the PKC inhibitor, rottlerin. Ischemic conditions were induced by lowering the glucose concentration from 22.5 mM to 1.375 mM. Under ischemic conditions, we found that phenylephrine also increased glucose oxidation. We report a direct role of α1-ARs in regulating glucose oxidation under normal and ischemic conditions that may lead to new therapeutic approaches in treating ischemia.
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Affiliation(s)
- Robert S Papay
- The Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Dianne M Perez
- The Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH, USA
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Lv Y, Hao J, Liu C, Huang H, Ma Y, Yang X, Tang L. Anti-diabetic effects of a phenolic-rich extract from Hypericum attenuatum Choisy in KK-Ay mice mediated through AMPK /PI3K/Akt/GSK3β signaling and GLUT4, PPARγ, and PPARα expression. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.103506] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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5
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Is there a Chance to Promote Arteriogenesis by DPP4 Inhibitors Even in Type 2 Diabetes? A Critical Review. Cells 2018; 7:cells7100181. [PMID: 30360455 PMCID: PMC6210696 DOI: 10.3390/cells7100181] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/08/2018] [Accepted: 10/18/2018] [Indexed: 12/18/2022] Open
Abstract
Cardiovascular diseases (CVD) are still the prevailing cause of death not only in industrialized countries, but even worldwide. Type 2 diabetes mellitus (type 2 DM) and hyperlipidemia, a metabolic disorder that is often associated with diabetes, are major risk factors for developing CVD. Recently, clinical trials proved the safety of gliptins in treating patients with type 2 DM. Gliptins are dipeptidyl-peptidase 4 (DPP4/CD26) inhibitors, which stabilize glucagon-like peptide-1 (GLP-1), thereby increasing the bioavailability of insulin. Moreover, blocking DPP4 results in increased levels of stromal cell derived factor 1 (SDF-1). SDF-1 has been shown in pre-clinical animal studies to improve heart function and survival after myocardial infarction, and to promote arteriogenesis, the growth of natural bypasses, compensating for the function of an occluded artery. Clinical trials, however, failed to demonstrate a superiority of gliptins compared to placebo treated type 2 DM patients in terms of cardiovascular (CV) outcomes. This review highlights the function of DPP4 inhibitors in type 2 DM, and in treating cardiovascular diseases, with special emphasis on arteriogenesis. It critically addresses the potency of currently available gliptins and gives rise to hope by pointing out the most relevant questions that need to be resolved.
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Huang Y, Hao J, Tian D, Wen Y, Zhao P, Chen H, Lv Y, Yang X. Antidiabetic Activity of a Flavonoid-Rich Extract From Sophora davidii (Franch.) Skeels in KK-Ay Mice via Activation of AMP-Activated Protein Kinase. Front Pharmacol 2018; 9:760. [PMID: 30061831 PMCID: PMC6055046 DOI: 10.3389/fphar.2018.00760] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/22/2018] [Indexed: 12/19/2022] Open
Abstract
The present study was undertaken to investigate the hypoglycemic activity and potential mechanisms of action of a flavonoid-rich extract from Sophora davidii (Franch.) Skeels (SD-FRE) through in vitro and in vivo studies. Four main flavonoids of SD-FRE namely apigenin, maackiain, leachianone A and leachianone B were purified and identified. In vitro, SD-FRE significantly promoted the translocation and expression of glucose transporter 4 (GLUT4) in L6 cells, which was significantly inhibited by Compound C (AMPK inhibitor), but not by Wortmannin (PI3K inhibitor) or Gö6983 (PKC inhibitor). These results indicated that SD-FRE enhanced GLUT4 expression and translocation to the plasma membrane via the AMPK pathway and finally resulted in an increase of glucose uptake. In vivo, using a spontaneously type 2 diabetic model, KK-Ay mice received intragastric administration of SD-FRE for 4 weeks. As a consequence, SD-FRE significantly alleviated the hyperglycemia, glucose intolerance, insulin resistance and hyperlipidemia in these mice. Hepatic steatosis, islet hypertrophy and larger adipocyte size were observed in KK-Ay mice. However, these pathological changes were effectively relieved by SD-FRE treatment. SD-FRE promoted GLUT4 expression and activated AMPK phosphorylation in insulin target tissues (muscle, adipose tissue and liver) of KK-Ay mice, thus facilitating glucose utilization to ameliorate insulin resistance. Regulation of ACC phosphorylation and PPARγ were also involved in the antidiabetic effects of SD-FRE. Taken together, these findings indicated that SD-FRE has the potential to alleviate type 2 diabetes.
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Affiliation(s)
- Yun Huang
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China
| | - Ji Hao
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China
| | - Di Tian
- School of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Yanzhang Wen
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China
| | - Ping Zhao
- School of Life Sciences, South-Central University for Nationalities, Wuhan, China
| | - Hao Chen
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China.,College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, China
| | - Yibin Lv
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China
| | - Xinzhou Yang
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China
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Sanni SJ, Kulahin N, Jorgensen R, Lyngsø C, Gammeltoft S, Hansen JL. A bioluminescence resonance energy transfer 2 (BRET2) assay for monitoring seven transmembrane receptor and insulin receptor crosstalk. J Recept Signal Transduct Res 2017; 37:590-599. [DOI: 10.1080/10799893.2017.1369123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Samra Joke Sanni
- Department of Obesity and Liver Disease, Novo Nordisk A/S, Maalov, Denmark
- Department of Clinical Biochemistry, Glostrup Research Institute, Glostrup Hospital, Glostrup, Denmark
| | - Nikolaj Kulahin
- Department of Obesity and Liver Disease, Novo Nordisk A/S, Maalov, Denmark
| | - Rasmus Jorgensen
- Department of Diabetes and Cardiovascular Disease, Novo Nordisk A/S, Maalov, Denmark
| | - Christina Lyngsø
- Department of Clinical Biochemistry, Glostrup Research Institute, Glostrup Hospital, Glostrup, Denmark
| | - Steen Gammeltoft
- Department of Clinical Biochemistry, Glostrup Research Institute, Glostrup Hospital, Glostrup, Denmark
| | - Jakob Lerche Hansen
- Department of Diabetes and Cardiovascular Disease, Novo Nordisk A/S, Maalov, Denmark
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da Silva Junior ED, Sato M, Merlin J, Broxton N, Hutchinson DS, Ventura S, Evans BA, Summers RJ. Factors influencing biased agonism in recombinant cells expressing the human α 1A -adrenoceptor. Br J Pharmacol 2017; 174:2318-2333. [PMID: 28444738 DOI: 10.1111/bph.13837] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/06/2017] [Accepted: 04/12/2017] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Agonists acting at GPCRs promote biased signalling via Gα or Gβγ subunits, GPCR kinases and β-arrestins. Since the demonstration of biased agonism has implications for drug discovery, it is essential to consider confounding factors contributing to bias. We have examined bias at human α1A -adrenoceptors stably expressed at low levels in CHO-K1 cells, identifying off-target effects at endogenous receptors that contribute to ERK1/2 phosphorylation in response to the agonist oxymetazoline. EXPERIMENTAL APPROACH Intracellular Ca2+ mobilization was monitored in a Flexstation® using Fluo 4-AM. The accumulation of cAMP and ERK1/2 phosphorylation were measured using AlphaScreen® proximity assays, and mRNA expression was measured by RT-qPCR. Ligand bias was determined using the operational model of agonism. KEY RESULTS Noradrenaline, phenylephrine, methoxamine and A61603 increased Ca2+ mobilization, cAMP accumulation and ERK1/2 phosphorylation. However, oxymetazoline showed low efficacy for Ca+2 mobilization, no effect on cAMP generation and high efficacy for ERK1/2 phosphorylation. The apparent functional selectivity of oxymetazoline towards ERK1/2 was related to off-target effects at 5-HT1B receptors endogenously expressed in CHO-K1 cells. Phenylephrine and methoxamine showed genuine bias towards ERK1/2 phosphorylation compared to Ca2+ and cAMP pathways, whereas A61603 displayed bias towards cAMP accumulation compared to ERK1/2 phosphorylation. CONCLUSION AND IMPLICATIONS We have shown that while adrenergic agonists display bias at human α1A -adrenoceptors, the marked bias of oxymetazoline for ERK1/2 phosphorylation originates from off-target effects. Commonly used cell lines express a repertoire of endogenous GPCRs that may confound studies on biased agonism at recombinant receptors.
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Affiliation(s)
| | - Masaaki Sato
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Jon Merlin
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Natalie Broxton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Dana S Hutchinson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Sabatino Ventura
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Bronwyn A Evans
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
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Lee-Young RS, Hoffman NJ, Murphy KT, Henstridge DC, Samocha-Bonet D, Siebel AL, Iliades P, Zivanovic B, Hong YH, Colgan TD, Kraakman MJ, Bruce CR, Gregorevic P, McConell GK, Lynch GS, Drummond GR, Kingwell BA, Greenfield JR, Febbraio MA. Glucose-6-phosphate dehydrogenase contributes to the regulation of glucose uptake in skeletal muscle. Mol Metab 2016; 5:1083-1091. [PMID: 27818934 PMCID: PMC5081409 DOI: 10.1016/j.molmet.2016.09.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 08/29/2016] [Accepted: 09/05/2016] [Indexed: 12/25/2022] Open
Abstract
Objective The development of skeletal muscle insulin resistance is an early physiological defect, yet the intracellular mechanisms accounting for this metabolic defect remained unresolved. Here, we have examined the role of glucose-6-phosphate dehydrogenase (G6PDH) activity in the pathogenesis of insulin resistance in skeletal muscle. Methods Multiple mouse disease states exhibiting insulin resistance and glucose intolerance, as well as obese humans defined as insulin-sensitive, insulin-resistant, or pre-diabetic, were examined. Results We identified increased glucose-6-phosphate dehydrogenase (G6PDH) activity as a common intracellular adaptation that occurs in parallel with the induction of insulin resistance in skeletal muscle and is present across animal and human disease states with an underlying pathology of insulin resistance and glucose intolerance. We observed an inverse association between G6PDH activity and nitric oxide synthase (NOS) activity and show that increasing NOS activity via the skeletal muscle specific neuronal (n)NOSμ partially suppresses G6PDH activity in skeletal muscle cells. Furthermore, attenuation of G6PDH activity in skeletal muscle cells via (a) increased nNOSμ/NOS activity, (b) pharmacological G6PDH inhibition, or (c) genetic G6PDH inhibition increases insulin-independent glucose uptake. Conclusions We have identified a novel, previously unrecognized role for G6PDH in the regulation of skeletal muscle glucose metabolism. Defective skeletal muscle G6PDH activity in multiple insulin resistant animal models. Demonstration of defective skeletal muscle G6PDH activity in pre-diabetic individuals. Identification of nNOSμ as a regulator of G6PDH activity in skeletal muscle. G6PDH activity modulates insulin-independent glucose uptake in skeletal muscle.
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Affiliation(s)
- Robert S Lee-Young
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia.
| | - Nolan J Hoffman
- Diabetes & Metabolism Division, Garvan Institute of Medical Research, NSW, Australia
| | - Kate T Murphy
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Darren C Henstridge
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Dorit Samocha-Bonet
- Diabetes & Metabolism Division, Garvan Institute of Medical Research, NSW, Australia
| | - Andrew L Siebel
- Metabolic and Vascular Physiology Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Peter Iliades
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Borivoj Zivanovic
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Yet H Hong
- Institute for Sports, Exercise and Active Living, Victoria University, Footscray, VIC, Australia
| | - Timothy D Colgan
- Muscle Research and Therapeutics Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Michael J Kraakman
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Clinton R Bruce
- School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC, Australia
| | - Paul Gregorevic
- Muscle Research and Therapeutics Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Glenn K McConell
- Institute for Sports, Exercise and Active Living, Victoria University, Footscray, VIC, Australia
| | - Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Grant R Drummond
- Vascular Biology and Immunopharmacology Group, Department of Pharmacology, Monash University, Clayton, VIC, Australia
| | - Bronwyn A Kingwell
- Metabolic and Vascular Physiology Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia
| | - Jerry R Greenfield
- Diabetes & Metabolism Division, Garvan Institute of Medical Research, NSW, Australia
| | - Mark A Febbraio
- Cellular and Molecular Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, VIC, Australia; Diabetes & Metabolism Division, Garvan Institute of Medical Research, NSW, Australia.
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Shi T, Papay RS, Perez DM. The role of α 1-adrenergic receptors in regulating metabolism: increased glucose tolerance, leptin secretion and lipid oxidation. J Recept Signal Transduct Res 2016; 37:124-132. [PMID: 27277698 DOI: 10.1080/10799893.2016.1193522] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The role of α1-adrenergic receptors (α1-ARs) and their subtypes in metabolism is not well known. Most previous studies were performed before the advent of transgenic mouse models and utilized transformed cell lines and poorly selective antagonists. We have now studied the metabolic regulation of the α1A- and α1B-AR subtypes in vivo using knock-out (KO) and transgenic mice that express a constitutively active mutant (CAM) form of the receptor, assessing subtype-selective functions. CAM mice increased glucose tolerance while KO mice display impaired glucose tolerance. CAM mice increased while KO decreased glucose uptake into white fat tissue and skeletal muscle with the CAM α1A-AR showing selective glucose uptake into the heart. Using indirect calorimetry, both CAM mice demonstrated increased whole body fatty acid oxidation, while KO mice preferentially oxidized carbohydrate. CAM α1A-AR mice displayed significantly decreased fasting plasma triglycerides and glucose levels while α1A-AR KO displayed increased levels of triglycerides and glucose. Both CAM mice displayed increased plasma levels of leptin while KO mice decreased leptin levels. Most metabolic effects were more efficacious with the α1A-AR subtype. Our results suggest that stimulation of α1-ARs results in a favorable metabolic profile of increased glucose tolerance, cardiac glucose uptake, leptin secretion and increased whole body lipid metabolism that may contribute to its previously recognized cardioprotective and neuroprotective benefits.
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Affiliation(s)
- Ting Shi
- a Department of Molecular Cardiology , Lerner Research Institute, Cleveland Clinic Foundation , Cleveland , OH , USA
| | - Robert S Papay
- a Department of Molecular Cardiology , Lerner Research Institute, Cleveland Clinic Foundation , Cleveland , OH , USA
| | - Dianne M Perez
- a Department of Molecular Cardiology , Lerner Research Institute, Cleveland Clinic Foundation , Cleveland , OH , USA
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11
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Sato M, Dehvari N, Oberg AI, Dallner OS, Sandström AL, Olsen JM, Csikasz RI, Summers RJ, Hutchinson DS, Bengtsson T. Improving type 2 diabetes through a distinct adrenergic signaling pathway involving mTORC2 that mediates glucose uptake in skeletal muscle. Diabetes 2014; 63:4115-29. [PMID: 25008179 DOI: 10.2337/db13-1860] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is an increasing worldwide epidemic of type 2 diabetes that poses major health problems. We have identified a novel physiological system that increases glucose uptake in skeletal muscle but not in white adipocytes. Activation of this system improves glucose tolerance in Goto-Kakizaki rats or mice fed a high-fat diet, which are established models for type 2 diabetes. The pathway involves activation of β2-adrenoceptors that increase cAMP levels and activate cAMP-dependent protein kinase, which phosphorylates mammalian target of rapamycin complex 2 (mTORC2) at S2481. The active mTORC2 causes translocation of GLUT4 to the plasma membrane and glucose uptake without the involvement of Akt or AS160. Stimulation of glucose uptake into skeletal muscle after activation of the sympathetic nervous system is likely to be of high physiological relevance because mTORC2 activation was observed at the cellular, tissue, and whole-animal level in rodent and human systems. This signaling pathway provides new opportunities for the treatment of type 2 diabetes.
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MESH Headings
- Animals
- Blood Glucose/metabolism
- Cells, Cultured
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Diabetes Mellitus, Experimental/etiology
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 2/etiology
- Diabetes Mellitus, Type 2/metabolism
- Diet, High-Fat/adverse effects
- Glucose Tolerance Test
- Glucose Transporter Type 4/metabolism
- Mechanistic Target of Rapamycin Complex 2
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Multiprotein Complexes/metabolism
- Muscle, Skeletal/metabolism
- Phosphorylation
- Proto-Oncogene Proteins c-akt/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, beta-2/metabolism
- Signal Transduction
- TOR Serine-Threonine Kinases/metabolism
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Affiliation(s)
- Masaaki Sato
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden Department of Pharmacology, Monash University, Clayton, Victoria, Australia Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Nodi Dehvari
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Anette I Oberg
- Department of Pharmacology, Monash University, Clayton, Victoria, Australia Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Olof S Dallner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden Laboratory of Molecular Genetics, Howard Hughes Medical Institute, The Rockefeller University, New York, NY
| | - Anna L Sandström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jessica M Olsen
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Robert I Csikasz
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Roger J Summers
- Department of Pharmacology, Monash University, Clayton, Victoria, Australia Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Dana S Hutchinson
- Department of Pharmacology, Monash University, Clayton, Victoria, Australia Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Tore Bengtsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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12
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Mascarello A, Silva Frederico MJ, Gomes Castro AJ, Mendes CP, Dutra MF, Woehl VM, Yunes RA, Mena Barreto Silva FR, Nunes RJ. Novel sulfonyl(thio)urea derivatives act efficiently both as insulin secretagogues and as insulinomimetic compounds. Eur J Med Chem 2014; 86:491-501. [DOI: 10.1016/j.ejmech.2014.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
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13
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Boyda HN, Procyshyn RM, Pang CCY, Barr AM. Peripheral adrenoceptors: the impetus behind glucose dysregulation and insulin resistance. J Neuroendocrinol 2013; 25:217-28. [PMID: 23140239 DOI: 10.1111/jne.12002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/10/2012] [Accepted: 11/04/2012] [Indexed: 12/20/2022]
Abstract
It is now accepted that several pharmacological drug treatments trigger clinical manifestations of glucose dysregulation, such as hyperglycaemia, glucose intolerance and insulin resistance, in part through poorly understood mechanisms. Persistent sympathoadrenal activation is linked to glucose dysregulation and insulin resistance, both of which significantly increase the risk of emergent endocrinological disorders, including metabolic syndrome and type 2 diabetes mellitus. Through the use of targeted mutagenesis and pharmacological methods, preclinical and clinical research has confirmed physiological glucoregulatory roles for several peripheral α- and β-adrenoceptor subtypes. Adrenoceptor isoforms in the pancreas (α(2A) and β(2) ), skeletal muscle (α(1A) and β(2) ), liver (α(1A & B) and β(2) ) and adipose tissue (α(1A) and β(1 & 3) ) are convincing aetiological targets that account for both immediate and long-lasting alterations in blood glucose homeostasis. Because significant overlap exists between the therapeutic applications of numerous classes of drugs and their associated adverse side-effects, a better understanding of peripheral adrenoceptor-mediated glucose metabolism is thus warranted. Therefore, at the same time as providing a brief review of glucose homeostasis in the periphery, the present review addresses both functional and pathophysiological roles of the mammalian α(1) , α(2) , and β-adrenoceptor isoforms in whole-body glucose turnover. We highlight evidence relating to the clinical use of common adrenergic drugs and their impacts on glucose metabolism.
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Affiliation(s)
- H N Boyda
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada.
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14
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Liu J, Zhang JF, Lu JZ, Zhang DL, Li K, Su K, Wang J, Zhang YM, Wang N, Yang ST, Bu L, Ou-yang JP. Astragalus polysaccharide stimulates glucose uptake in L6 myotubes through AMPK activation and AS160/TBC1D4 phosphorylation. Acta Pharmacol Sin 2013; 34:137-45. [PMID: 23103623 DOI: 10.1038/aps.2012.133] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To establish the mechanism responsible for the stimulation of glucose uptake by Astragalus polysaccharide (APS), extracted from Astragalus membranaceus Bunge, in L6 myotubes in vitro. METHODS APS-stimulated glucose uptake in L6 myotubes was measured using the 2-deoxy-[(3)H]-D-glucose method. The adenine nucleotide contents in the cells were measured by HPLC. The phosphorylation of AMP-activated protein kinase (AMPK) and Akt substrate of 160 kDa (AS160) was examined using Western blot analysis. The cells transfected with 4P mutant AS160 (AS160-4P) were constructed using gene transfer approach. RESULTS Treatment of L6 myotubes with APS (100-1600 μg/mL) significantly increased glucose uptake in time- and concentration-dependent manners. The maximal glucose uptake was reached in the cells treated with APS (400 μg/mL) for 36 h. The APS-stimulated glucose uptake was significantly attenuated by pretreatment with Compound C, a selective AMPK inhibitor or in the cells overexpressing AS160-4P. Treatment of L6 myotubes with APS strongly promoted the activation of AMPK. We further demonstrated that either Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ) or liver kinase B1 (LKB1) mediated APS-induced activation of AMPK in L6 myotubes, and the increased cellular AMP: ATP ratio was also involved. Treatment of L6 myotubes with APS robustly enhanced the phosphorylation of AS160, which was significantly attenuated by pretreatment with Compound C. CONCLUSION Our results demonstrate that APS stimulates glucose uptake in L6 myotubes through the AMP-AMPK-AS160 pathway, which may contribute to its hypoglycemic effect.
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Hong NY, Cui ZG, Kang HK, Lee DH, Lee YK, Park DB. p-Synephrine stimulates glucose consumption via AMPK in L6 skeletal muscle cells. Biochem Biophys Res Commun 2012; 418:720-4. [PMID: 22306011 DOI: 10.1016/j.bbrc.2012.01.085] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 01/18/2012] [Indexed: 11/19/2022]
Abstract
Interest in p-synephrine, the primary protoalkaloid in the extract of bitter orange and other citrus species, has increased due to its various pharmacological effects and related adverse effects. The lipolytic activity of p-synephrine has been repeatedly revealed by in vitro and in vivo studies and p-synephrine is currently marketed as a dietary supplement for weight loss. The present study investigated the effect of p-synephrine on glucose consumption and its action mechanism in L6 skeletal muscle cells. Treatment of L6 skeletal muscle cells with p-synephrine (0-100μM) did not affect cell viability and increased basal glucose consumption up to 50% over the control in a dose-dependent manner. The basal- or insulin-stimulated lactic acid production as well as glucose consumption was significantly increased by the addition of p-synephrine. p-Synephrine stimulated the phosphorylation of AMPK but not of Akt. p-Synephrine-induced glucose consumption was sensitive to the inhibition of AMPK but not to the inhibition of PI3 kinase. p-Synephrine also stimulated the translocation of Glut4 from the cytoplasm to the plasma membrane; this stimulation was suppressed by the inhibition of AMPK, but not of PI3 kinase. Taken together, p-synephrine can stimulate glucose consumption (Glut4-dependent glucose uptake) by stimulating AMPK activity, regardless of insulin-stimulated PI3 kinase-Akt activity in L6 skeletal muscle cells.
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Affiliation(s)
- Na-Young Hong
- Department of Medicine, School of Medicine, Institute of Medical Science, Jeju National University, 690-756 Jeju, Republic of Korea
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Sattin A, Pekary AE, Blood J. Rapid modulation of TRH and TRH-like peptide release in rat brain and peripheral tissues by prazosin. Peptides 2011; 32:1666-76. [PMID: 21718733 DOI: 10.1016/j.peptides.2011.06.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 06/11/2011] [Accepted: 06/13/2011] [Indexed: 11/28/2022]
Abstract
Hyperresponsiveness to norepinephrine contributes to post-traumatic stress disorder (PTSD). Prazosin, a brain-active blocker of α(1)-adrenoceptors, originally used for the treatment of hypertension, has been reported to alleviate trauma nightmares, sleep disturbance and improve global clinical status in war veterans with PTSD. Thyrotropin-releasing hormone (TRH, pGlu-His-Pro-NH(2)) may play a role in the pathophysiology and treatment of neuropsychiatric disorders such as major depression, and PTSD (an anxiety disorder). To investigate whether TRH or TRH-like peptides (pGlu-X-Pro-NH(2), where "X" can be any amino acid residue) participate in the therapeutic effects of prazosin, male rats were injected with prazosin and these peptides then measured in brain and endocrine tissues. Prazosin stimulated TRH and TRH-like peptide release in those tissues with high α(1)-adrenoceptor levels suggesting that these peptides may play a role in the therapeutic effects of prazosin.
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Affiliation(s)
- Albert Sattin
- Psychiatry Services, VA Greater Los Angeles Healthcare System, CA 90073, USA
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Öberg AI, Yassin K, Csikasz RI, Dehvari N, Shabalina IG, Hutchinson DS, Wilcke M, Östenson CG, Bengtsson T. Shikonin increases glucose uptake in skeletal muscle cells and improves plasma glucose levels in diabetic Goto-Kakizaki rats. PLoS One 2011; 6:e22510. [PMID: 21818330 PMCID: PMC3144218 DOI: 10.1371/journal.pone.0022510] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 06/28/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND There is considerable interest in identifying compounds that can improve glucose homeostasis. Skeletal muscle, due to its large mass, is the principal organ for glucose disposal in the body and we have investigated here if shikonin, a naphthoquinone derived from the Chinese plant Lithospermum erythrorhizon, increases glucose uptake in skeletal muscle cells. METHODOLOGY/PRINCIPAL FINDINGS Shikonin increases glucose uptake in L6 skeletal muscle myotubes, but does not phosphorylate Akt, indicating that in skeletal muscle cells its effect is medaited via a pathway distinct from that used for insulin-stimulated uptake. Furthermore we find no evidence for the involvement of AMP-activated protein kinase in shikonin induced glucose uptake. Shikonin increases the intracellular levels of calcium in these cells and this increase is necessary for shikonin-mediated glucose uptake. Furthermore, we found that shikonin stimulated the translocation of GLUT4 from intracellular vesicles to the cell surface in L6 myoblasts. The beneficial effect of shikonin on glucose uptake was investigated in vivo by measuring plasma glucose levels and insulin sensitivity in spontaneously diabetic Goto-Kakizaki rats. Treatment with shikonin (10 mg/kg intraperitoneally) once daily for 4 days significantly decreased plasma glucose levels. In an insulin sensitivity test (s.c. injection of 0.5 U/kg insulin), plasma glucose levels were significantly lower in the shikonin-treated rats. In conclusion, shikonin increases glucose uptake in muscle cells via an insulin-independent pathway dependent on calcium. CONCLUSIONS/SIGNIFICANCE Shikonin increases glucose uptake in skeletal muscle cells via an insulin-independent pathway dependent on calcium. The beneficial effects of shikonin on glucose metabolism, both in vitro and in vivo, show that the compound possesses properties that make it of considerable interest for developing novel treatment of type 2 diabetes.
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Affiliation(s)
- Anette I. Öberg
- Department of Physiology, Arrhenius Laboratories F3, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Kamal Yassin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Robert I. Csikasz
- Department of Physiology, Arrhenius Laboratories F3, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Nodi Dehvari
- Department of Physiology, Arrhenius Laboratories F3, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Irina G. Shabalina
- Department of Physiology, Arrhenius Laboratories F3, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Dana S. Hutchinson
- Department of Pharmacology, Monash University, Parkville, Victoria, Australia
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | | | - Claes-Göran Östenson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Tore Bengtsson
- Department of Physiology, Arrhenius Laboratories F3, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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Pharmacological modulation of dopamine receptor D2-mediated transmission alters the metabolic phenotype of diet induced obese and diet resistant C57Bl6 mice. EXPERIMENTAL DIABETES RESEARCH 2011; 2011:928523. [PMID: 21603181 PMCID: PMC3096057 DOI: 10.1155/2011/928523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 02/09/2011] [Indexed: 11/18/2022]
Abstract
High fat feeding induces a variety of obese and lean phenotypes in inbred rodents. Compared to Diet Resistant (DR) rodents, Diet Induced Obese (DIO) rodents are insulin resistant and have a reduced dopamine receptor D2 (DRD2) mediated tone. We hypothesized that this differing dopaminergic tone contributes to the distinct metabolic profiles of these animals.
C57Bl6 mice were classified as DIO or DR based on their weight gain during 10 weeks of high fat feeding. Subsequently DIO mice were treated with the DRD2 agonist bromocriptine and DR mice with the DRD2 antagonist haloperidol for 2 weeks.
Compared to DR mice, the bodyweight of DIO mice was higher and their insulin sensitivity decreased. Haloperidol treatment reduced the voluntary activity and energy expenditure of DR mice and induced insulin resistance in these mice. Conversely, bromocriptine treatment tended to reduce bodyweight and voluntary activity, and reinforce insulin action in DIO mice.
These results show that DRD2 activation partly redirects high fat diet induced metabolic anomalies in obesity-prone mice. Conversely, blocking DRD2 induces an adverse metabolic profile in mice that are inherently resistant to the deleterious effects of high fat food. This suggests that dopaminergic neurotransmission is involved in the control of metabolic phenotype.
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Genistein stimulates duodenal HCO(3)(-) secretion through PI3K pathway in mice. Eur J Pharmacol 2010; 651:159-67. [PMID: 21093426 DOI: 10.1016/j.ejphar.2010.10.070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 10/10/2010] [Accepted: 10/29/2010] [Indexed: 11/20/2022]
Abstract
Genistein has been proposed as a promising pharmacotherapeutic for cystic fibrosis. We recently found that genistein stimulates murine duodenal HCO(3)(-) secretion through cystic fibrosis transmembrane conductance regulator (CFTR). The aim of the present study was to determine the intracellular signal pathways involved in genistein-stimulated duodenal HCO(3)(-) secretion. Murine duodenal mucosal HCO(3)(-) secretion was examined in vitro in Ussing chambers by the pH-stat technique. The results showed that neither cAMP-dependent signal pathway inhibitors MDL-12330A and KT-5720, nor cGMP signal pathway inhibitors NS2028 and KT5823, nor calcium signal pathway inhibitors verapamil and W-13, altered genistein-stimulated duodenal HCO(3)(-) secretion. In calcium-free solution, genistein-stimulated duodenal HCO(3)(-) secretion was not altered either. Vanadate, an inhibitor of protein tyrosine phosphatase, only partially inhibited genistein-stimulated duodenal HCO(3)(-) secretion. However, both wortmannin and LY294002, two structurally and mechanistically distinct phosphatidylinositol 3-kinase (PI3K) inhibitors, markedly inhibited genistein-stimulated duodenal HCO(3)(-) secretion. Genistein increased duodenal mucosal PI3K activity and induced the phosphorylation of Akt, a signaling molecule downstream of PI3K, which was again inhibited by wortmannin. Estrogen receptor antagonist, ICI182,780, also markedly inhibited genistein-stimulated duodenal HCO(3)(-) secretion and genistein-induced PI3K activity increase in duodenal mucosa. These results demonstrate that genistein stimulates duodenal HCO(3)(-) secretion mainly through estrogen receptor and PI3K-dependent pathway. These findings contribute to the understanding of the molecular mechanism of genistein-induced anion secretion and further pharmacotherapeutic development and use of genistein or related substances in the treatment of diseases of epithelial tissues.
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Merlin J, Evans BA, Csikasz RI, Bengtsson T, Summers RJ, Hutchinson DS. The M3-muscarinic acetylcholine receptor stimulates glucose uptake in L6 skeletal muscle cells by a CaMKK-AMPK-dependent mechanism. Cell Signal 2010; 22:1104-13. [PMID: 20206685 DOI: 10.1016/j.cellsig.2010.03.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 02/23/2010] [Accepted: 03/01/2010] [Indexed: 11/15/2022]
Abstract
The role of muscarinic acetylcholine receptors (mAChRs) in regulating glucose uptake in L6 skeletal muscle cells was investigated. [(3)H]-2-Deoxyglucose uptake was increased in differentiated L6 cells by insulin, acetylcholine, oxotremorine-M and carbachol. mAChR-mediated glucose uptake was inhibited by the AMPK inhibitor Compound C. Whole cell radioligand binding using [(3)H]-N-methyl scopolamine chloride identified mAChRs in differentiated but not undifferentiated L6 cells and M(3) mAChR mRNA was detected only in differentiated cells. M(3) mAChRs are Gq-coupled, and cholinergic stimulation by the mAChR agonists acetylcholine, oxotremorine-M and carbachol increased Ca(2+) in differentiated but not undifferentiated L6 cells. This was due to muscarinic but not nicotinic activation as responses were antagonised by the muscarinic antagonist atropine but not the nicotinic antagonist tubocurarine. Western blotting showed that both carbachol and the AMPK activator AICAR increased phosphorylation of the AMPKalpha subunit at Thr172, with responses to carbachol blocked by Compound C and the CaMKK inhibitor STO609 but not by the PI3K inhibitor wortmannin. AICAR-stimulated AMPK phosphorylation was not sensitive to STO-609, confirming that this compound inhibits CaMKK but not the classical AMPK kinase LKB1. The TAK1 inhibitor (5Z)-7-oxozeaenol and the G(i) inhibitor pertussis toxin both failed to block AMPK phosphorylation in response to carbachol. Using CHO-K1 cells stably expressing each of the mAChR subtypes (M(1)-M(4)), it was determined that only the M(1) and M(3) mAChRs phosphorylate AMPK, confirming a G(q)-dependent mechanism. This study demonstrates that activation of M(3) mAChRs in L6 skeletal muscle cells stimulates glucose uptake via a CaMKK-AMPK-dependent mechanism, independent of the insulin-stimulated pathway.
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Affiliation(s)
- Jon Merlin
- Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Victoria, 3800, Australia
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21
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Cheng TC, Lin CS, Hsu CC, Chen LJ, Cheng KC, Cheng JT. Activation of muscarinic M-1 cholinoceptors by curcumin to increase glucose uptake into skeletal muscle isolated from Wistar rats. Neurosci Lett 2009; 465:238-41. [PMID: 19765405 DOI: 10.1016/j.neulet.2009.09.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 09/08/2009] [Accepted: 09/11/2009] [Indexed: 02/04/2023]
Abstract
Curcumin, an active principle contained in rhizome of Curcuma longa, has been mentioned to show merit for diabetes through its anti-oxidative and anti-inflammatory properties. In the present study, we found that curcumin caused a concentration-dependent increase of glucose uptake into skeletal muscle isolated from Wistar rats. This action was inhibited by pirenzepine at concentration enough to block muscarinic M-1 cholinoceptor (M(1)-mAChR). In radioligand binding assay, the binding of [(3)H]-pirenzepine was also displaced by curcumin in a concentration-dependent manner. In the presence of inhibitors for PLC-PI3K pathway, either U73122 (phospholipase C inhibitor) or LY294002 (phosphoinositide 3-kinase inhibitor), curcumin-stimulated glucose uptake into skeletal muscle was markedly reduced. In Western blotting analysis, the membrane protein level of glucose transporter 4 (GLUT4) increased by curcumin was also reversed by blockade of M(1)-mAChR or PLC-PI3K pathway in a same manner. In conclusion, the obtained results suggest that curcumin can activate M(1)-mAChR at concentrations lower than to scavenge free radicals for increase of glucose uptake into skeletal muscle through PLC-PI3-kinase pathway.
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Affiliation(s)
- Tse-Chou Cheng
- Department of Urology, Chi-Mei Medical Center, Yong Kang, Taiwan, ROC
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Tuo B, Wen G, Zhang Y, Liu X, Wang X, Liu X, Dong H. Involvement of phosphatidylinositol 3-kinase in cAMP- and cGMP-induced duodenal epithelial CFTR activation in mice. Am J Physiol Cell Physiol 2009; 297:C503-15. [PMID: 19535511 DOI: 10.1152/ajpcell.00460.2008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although phosphatidylinositol 3-kinase (PI3K) is essential for several cellular signal transductions, its role in the regulation of cystic fibrosis transmembrane conductance regulator (CFTR) activity in intestinal epithelial cells is poorly understood. Therefore, the possible involvement of PI3K in the regulation of cAMP- and cGMP-induced duodenal epithelial CFTR activation was investigated in the present study. Forskolin and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) markedly stimulated duodenal mucosal HCO(3)(-) secretion and short-circuit current (I(sc)) in CFTR wild-type mice, which was significantly inhibited by CFTR(inh)-172, a highly potent and specific CFTR inhibitor. Forskolin and 8-Br-cGMP failed to stimulate duodenal HCO(3)(-) secretion and I(sc) in CFTR knockout mice. Moreover, forskolin- and 8-Br-cGMP-stimulated duodenal HCO(3)(-) secretion and I(sc) were significantly reduced by wortmannin and LY294002, two selective PI3K inhibitors that are structurally and mechanistically different. Forskolin and 8-Br-cGMP induced CFTR phosphorylation and shifted CFTR proteins to the plasma membrane of duodenal epithelial cells, which were inhibited by wortmannin and LY294002. Forskolin and 8-Br-cGMP not only increased the activity of PI3K but also induced the phosphorylation of Akt, a signaling molecule downstream of PI3K, which were again inhibited by wortmannin and LY294002. Together, our results obtained from functional, biochemical, and morphological studies demonstrate that PI3K pathway plays an important role in the regulation of cAMP- and cGMP-induced duodenal epithelial CFTR channel activity and intracellular trafficking.
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Affiliation(s)
- Biguang Tuo
- Dept. of Gastroenterology, Affiliated Hospital of Zunyi Medical College, Dalian Road 149, Zunyi 563003, China.
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Alterations of insulin signaling in type 2 diabetes: A review of the current evidence from humans. Biochim Biophys Acta Mol Basis Dis 2009; 1792:83-92. [DOI: 10.1016/j.bbadis.2008.10.019] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 10/21/2008] [Accepted: 10/21/2008] [Indexed: 01/03/2023]
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Yea K, Kim J, Lim S, Kwon T, Park HS, Park KS, Suh PG, Ryu SH. Lysophosphatidylserine regulates blood glucose by enhancing glucose transport in myotubes and adipocytes. Biochem Biophys Res Commun 2008; 378:783-8. [PMID: 19063864 DOI: 10.1016/j.bbrc.2008.11.122] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 11/23/2008] [Indexed: 12/27/2022]
Abstract
Lysophosphatidylserine (LPS) is known to have diverse cellular effects, but although LPS is present in many biological fluids, its in vivo effects have not been elucidated. In the present study, we investigated the effects of LPS on glucose metabolism in vivo, and how skeletal muscle cells respond to LPS stimulation. LPS enhanced glucose uptake in a dose- and time-dependent manner in L6 GLUT4myc myotubes, and this effect of LPS on glucose uptake was mediated by a Galpha(i) and PI 3-kinase dependent signal pathway. LPS increased the level of GLUT4 on the cell surface of L6 GLUT4myc myotubes, and enhanced glucose uptake in 3T3-L1 adipocytes. In line with its cellular functions, LPS lowered blood glucose levels in normal mice, while leaving insulin secretion unaffected. LPS also had a glucose-lowering effect in STZ-treated type 1 diabetic mice and in obese db/db type 2 diabetic mice. This study shows that LPS-stimulated glucose transport both in skeletal muscle cells and adipocytes, and significantly lowered blood glucose levels both in type 1 and 2 diabetic mice. Our results suggest that LPS is involved in the regulation of glucose homeostasis in skeletal muscle and adipose tissue.
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Affiliation(s)
- Kyungmoo Yea
- Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, South Korea
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Hutchinson DS, Summers RJ, Bengtsson T. Regulation of AMP-activated protein kinase activity by G-protein coupled receptors: Potential utility in treatment of diabetes and heart disease. Pharmacol Ther 2008; 119:291-310. [DOI: 10.1016/j.pharmthera.2008.05.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 05/27/2008] [Indexed: 12/25/2022]
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Role of beta-adrenoceptors in memory consolidation: beta3-adrenoceptors act on glucose uptake and beta2-adrenoceptors on glycogenolysis. Neuropsychopharmacology 2008; 33:2384-97. [PMID: 18046311 DOI: 10.1038/sj.npp.1301629] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Noradrenaline, acting via beta(2)- and beta(3)-adrenoceptors (AR), enhances memory formation in single trial-discriminated avoidance learning in day-old chicks by mechanisms involving changes in metabolism of glucose and/or glycogen. Earlier studies of memory consolidation in chicks implicated beta(3)- rather than beta(2)-ARs in enhancement of memory consolidation by glucose, but did not elucidate whether stimulation of glucose uptake or of glycolysis was responsible. This study examines the role of glucose transport in memory formation using central injection of the nonselective facilitative glucose transporter (GLUT) inhibitor cytochalasin B, the endothelial/astrocytic GLUT-1 inhibitor phloretin and the Na(+)/energy-dependent endothelial glucose transporter (SGLT) inhibitor phlorizin. Cytochalasin B inhibited memory when injected into the mesopallium (avian cortex) either close to or between 25 and 45 min after training, whereas phloretin and phlorizin only inhibited memory at 30 min. This suggested that astrocytic/endothelial (GLUT-1) transport is critical at the time of consolidation, whereas a different transporter, probably the neuronal glucose transporter (GLUT-3), is important at the time of training. Inhibition of glucose transport by cytochalasin B, phloretin, or phlorizin also interfered with beta(3)-AR-mediated memory enhancement 20 min posttraining, whereas inhibition of glycogenolysis interfered with beta(2)-AR agonist enhancement of memory. We conclude that in astrocytes (1) activities of both GLUT-1 and SGLT are essential for memory consolidation 30 min posttraining; (2) neuronal GLUT-3 is essential at the time of training; and (3) beta(2)- and beta(3)-ARs consolidate memory by different mechanisms; beta(3)-ARs stimulate central glucose transport, whereas beta(2)-ARs stimulate central glycogenolysis.
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Hutchinson DS, Summers RJ, Gibbs ME. Energy metabolism and memory processing: role of glucose transport and glycogen in responses to adrenoceptor activation in the chicken. Brain Res Bull 2008; 76:224-34. [PMID: 18498935 DOI: 10.1016/j.brainresbull.2008.02.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 01/22/2008] [Accepted: 02/11/2008] [Indexed: 11/28/2022]
Abstract
From experiments using a discriminated bead task in young chicks, we have defined when and where adrenoceptors (ARs) are involved in memory modulation. All three ARs subtypes (alpha(1)-, alpha(2)- and beta-ARs) are found in the chick brain and in regions associated with memory. Glucose and glycogen are important in the role of memory consolidation in the chick since increasing glucose levels improves memory consolidation while inhibiting glucose transporters (GLUTs) or glycogen breakdown inhibits memory consolidation. The selective beta(3)-AR agonist CL316243 enhances memory consolidation by a glucose-dependent mechanism and the administration of the non-metabolized glucose analogue 2-deoxyglucose reduces the ability of CL316243 to enhance memory. Agents that reduce glucose uptake by GLUTs and its incorporation into the glycolytic pathway also reduce the effectiveness of CL316243, but do not alter the dose-response relationship to the beta(2)-AR agonist zinterol. However, beta(2)-ARs do have a role in memory related to glycogen breakdown and inhibition of glycogenolysis reduces the ability of zinterol to enhance memory. Both beta(2)- and beta(3)-ARs are found on astrocytes from chick forebrain, and the actions of beta(3)-ARs on glucose uptake, and beta(2)-ARs on the breakdown of glycogen is consistent with an effect on astrocytic metabolism at the time of memory consolidation 30 min after training. We have shown that both beta(2)- and beta(3)-ARs can increase glucose uptake in chick astrocytes but do so by different mechanisms. This review will focus on the role of ARs on memory consolidation and specifically the role of energy metabolism on AR modulation of memory.
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Affiliation(s)
- Dana S Hutchinson
- Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia.
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Oxidative stress and alpha1-adrenoceptor-mediated stimulation of the Cl-/HCO3- exchanger in immortalized SHR proximal tubular epithelial cells. Br J Pharmacol 2008; 153:1445-55. [PMID: 18297111 DOI: 10.1038/bjp.2008.16] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE This study evaluated the signalling coupled to the alpha1-adrenoceptor-induced stimulation of the Cl-/HCO3- exchanger in hypertension. EXPERIMENTAL APPROACH The Na+ -independent HCO3- transport system activity was assayed as the initial rate of pHi recovery after an alkaline load (CO2/HCO3 removal) in immortalized renal proximal tubular epithelial cells from spontaneously hypertensive rat (SHR) and their normotensive control (Wistar Kyoto rat; WKY). KEY RESULTS Noradrenaline increased Cl-/HCO3- exchanger activity with EC50 values of 0.6 and 5.3 microM in SHR and WKY cells, respectively. These effects were abolished by prazosin, but not by yohimbine. Phenylephrine increased Cl-/HCO3- exchanger activity in SHR and WKY cells (EC50 of 2.6 and 4.9 microM, respectively). Phenylephrine-mediated increase in Cl-/HCO3- exchanger activity in WKY and SHR cells was inhibited by protein kinase C (PKC), MAPK/ERK kinase (MEK) and p38 mitogen-activated protein kinase (p38 MAPK) inhibitors. The expression of alpha1A- and alpha1B-adrenoceptors was identical in WKY and SHR cells. SHR cells generated more H2O2 than WKY cells. In SHR cells, the NADPH oxidase inhibitor apocynin reduced their increased ability to generate H2O2 and abolished their hypersensitivity to phenylephrine, but failed to affect basal Cl-/HCO3- exchanger activity. H2O2-dependent stimulation of Cl-/HCO3- exchange activity was significantly higher in SHR than in WKY cells. CONCLUSIONS AND IMPLICATIONS Differences between WKY and SHR cells on their sensitivity to alpha1-adrenoceptor stimulation did not correlate with the abundance of alpha1A- and alpha1B-adrenoceptors and may be related to the increased generation of H2O2, which may amplify the response downstream of alpha1-adrenoceptor activation.
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Hutchinson DS, Summers RJ, Gibbs ME. β2- and β3-Adrenoceptors activate glucose uptake in chick astrocytes by distinct mechanisms: a mechanism for memory enhancement? J Neurochem 2007; 103:997-1008. [PMID: 17680985 DOI: 10.1111/j.1471-4159.2007.04789.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Isoprenaline, acting at beta-adrenoceptors (ARs), enhances memory formation in single trial discriminated avoidance learning in day-old chicks by mechanisms involving alterations in glucose and glycogen metabolism. Earlier studies of memory consolidation in chicks indicated that beta3-ARs enhanced memory by increasing glucose uptake, whereas beta2-ARs enhance memory by increasing glycogenolysis. This study examines the ability of beta-ARs to increase glucose uptake in chick forebrain astrocytes. The beta-AR agonist isoprenaline increased glucose uptake in a concentration-dependent manner, as did insulin. Glucose uptake was increased by the beta2-AR agonist zinterol and the beta3-AR agonist CL316243, but not by the beta1-AR agonist RO363. In chick astrocytes, reverse transcription-polymerase chain reaction studies showed that beta1-, beta2-, and beta3-AR mRNA were present, whereas radioligand-binding studies showed the presence of only beta2- and beta3-ARs. beta-AR or insulin-mediated glucose uptake was inhibited by phosphatidylinositol-3 kinase and protein kinase C inhibitors, suggesting a possible interaction between the beta-AR and insulin pathways. However beta2- and beta3-ARs increase glucose uptake by two different mechanisms: beta2-ARs via a Gs-cAMP-protein kinase A-dependent pathway, while beta3-ARs via interactions with Gi. These results indicate that activation of beta2- and beta3-ARs causes glucose uptake in chick astrocytes by distinct mechanisms, which may be relevant for memory enhancement.
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MESH Headings
- Adrenergic beta-2 Receptor Agonists
- Adrenergic beta-3 Receptor Agonists
- Adrenergic beta-Agonists/pharmacology
- Animals
- Astrocytes/drug effects
- Astrocytes/metabolism
- Brain/cytology
- Brain/metabolism
- Cells, Cultured
- Chick Embryo
- Dioxoles/pharmacology
- Dose-Response Relationship, Drug
- Enzyme Inhibitors/pharmacology
- Ethanolamines/pharmacology
- GTP-Binding Protein alpha Subunits, Gi-Go/drug effects
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gs/drug effects
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Glucose/metabolism
- Glucose/pharmacokinetics
- Insulin/metabolism
- Insulin/pharmacology
- Isoproterenol/pharmacology
- Memory/drug effects
- Memory/physiology
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoinositide-3 Kinase Inhibitors
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Adrenergic, beta-3/genetics
- Receptors, Adrenergic, beta-3/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
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30
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Yea K, Kim J, Lim S, Park HS, Park KS, Suh PG, Ryu SH. Lysophosphatidic acid regulates blood glucose by stimulating myotube and adipocyte glucose uptake. J Mol Med (Berl) 2007; 86:211-20. [PMID: 17924084 DOI: 10.1007/s00109-007-0269-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Revised: 09/06/2007] [Accepted: 09/13/2007] [Indexed: 01/06/2023]
Abstract
Lysophosphatidic acid (LPA) is known to have diverse cellular effects, but although LPA is present in many biological fluids, including blood, its effects on glucose metabolism have not been elucidated. In this study, we investigated whether LPA stimulation is related to glucose regulation. LPA was found to enhance glucose uptake in a dose-dependent manner both in L6 GLUT4myc myotubes and 3T3-L1 adipocytes by triggering GLUT4 translocation to the plasma membrane. Moreover, the effect of LPA on glucose uptake was completely inhibited by pretreating both cells with LPA receptor antagonist Ki16425 and Gi inhibitor pertussis toxin. In addition, LPA increased the phosphorylation of AKT-1 with no effects on IRS-1, and LPA-induced glucose uptake was abrogated by pretreatment with the PI 3-kinase inhibitor LY294002. When low concentration of insulin and LPA were treated simultaneously, an additive effect on glucose uptake was observed in both cell types. In line with its cellular functions, LPA significantly lowered blood glucose levels in normal mice but did not affect insulin secretion. LPA also had a glucose-lowering effect in streptozotocin-treated type 1 diabetic mice. In combination, these results suggest that LPA is involved in the regulation of glucose homeostasis in muscle and adipose tissues.
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Affiliation(s)
- Kyungmoo Yea
- Division of Molecular and Life Science, Pohang University of Science and Technology, San 31 Hyojadong, Pohang, 790-784, South Korea
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31
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Tuo BG, Wen GR, Seidler U. Phosphatidylinositol 3-kinase is involved in prostaglandin E2-mediated murine duodenal bicarbonate secretion. Am J Physiol Gastrointest Liver Physiol 2007; 293:G279-87. [PMID: 17495030 DOI: 10.1152/ajpgi.00488.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Prostaglandin E(2) (PGE(2)) plays an important role in the regulation of duodenal bicarbonate (HCO(3)(-)) secretion, but its signaling pathway(s) are not fully understood. In the present study, we investigated the signaling pathways involved in PGE(2)-mediated duodenal HCO(3)(-) secretion. Murine duodenal mucosal HCO(3)(-) secretion was examined in vitro in Ussing chambers by pH-stat titration in the presence of a variety of signal transduction modulators. Phosphatidylinositol 3-kinase (PI3K) activity was measured by immunoprecipitation of PI3K and ELISA, and Akt phosphorylation was measured by Western analysis with anti-phospho-Akt and anti-Akt antibodies. PGE(2)-stimulated duodenal HCO(3)(-) secretion was reduced by the cAMP-dependent signaling pathway inhibitors MDL-12330A and KT-5720 by 23% and 20%, respectively; the Ca(2+)-influx inhibitor verapamil by 26%; and the calmodulin antagonist W-13 by 24%; whereas the PI3K inhibitors wortmannin and LY-294002 reduced PGE(2)-stimulated HCO(3)(-) secretion by 51% and 47%, respectively. Neither the MAPK inhibitor PD-98059 nor the tyrosine kinase inhibitor genistein altered PGE(2)-stimulated HCO(3)(-) secretion. PGE(2) application caused a rapid and concentration-dependent increase in duodenal mucosal PI3K activity and Akt phosphorylation. These results demonstrated that PGE(2) activates PI3K in duodenal mucosa and stimulates duodenal HCO(3)(-) secretion via cAMP-, Ca(2+)-, and PI3K-dependent signaling pathways.
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Affiliation(s)
- Bi-Guang Tuo
- Department of Gastroenterology, Hepatology, and Endocrinology, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany
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32
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Faenza I, Ramazzotti G, Bavelloni A, Fiume R, Gaboardi GC, Follo MY, Gilmour RS, Martelli AM, Ravid K, Cocco L. Inositide-dependent phospholipase C signaling mimics insulin in skeletal muscle differentiation by affecting specific regions of the cyclin D3 promoter. Endocrinology 2007; 148:1108-17. [PMID: 17122077 DOI: 10.1210/en.2006-1003] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Our main goal in this study was to investigate the role of phospholipase C (PLC) beta(1) and PLCgamma(1) in skeletal muscle differentiation and the existence of potential downstream targets of their signaling activity. To examine whether PLC signaling can modulate the expression of cyclin D3, a target of PLCbeta(1) in erythroleukemia cells, we transfected C2C12 cells with expression vectors containing PLCbeta(1) or PLCgamma(1) cDNA and with small interfering RNAs from regions of the PLCbeta(1) or PLCgamma(1) gene and followed myogenic differentiation in this well-established cell system. Intriguingly, overexpressed PLCbeta(1) and PLCgamma(1) were able to mimic insulin induction of both cyclin D3 and muscle differentiation. By knocking down PLCbeta(1) or PLCgamma(1) expression, C2C12 cells almost completely lost the increase in cyclin D3, and the differentiation program was down-regulated. To explore the induction of the cyclin D3 gene promoter during this process, we used a series of 5'-deletions of the 1.68-kb promoter linked to a reporter gene and noted a 5-fold augmentation of promoter activity upon insulin stimulation. These constructs were also cotransfected with PLCbeta(1) or PLCgamma(1) cDNAs and small interfering RNAs, respectively. Our data indicate that PLCbeta(1) or PLCgamma(1) signaling is capable of acting like insulin in regard to both the myogenic differentiation program and cyclin D3 up-regulation. Taken together, this is the first study that hints at cyclin D3 as a target of PLCbeta(1) and PLCgamma(1) during myogenic differentiation in vitro and implies that up-regulation of these enzymes is sufficient to mimic the actions of insulin in this process.
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Affiliation(s)
- Irene Faenza
- Cellular Signalling Laboratory, Department of Human Anatomical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
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33
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Yamamoto DL, Hutchinson DS, Bengtsson T. Beta(2)-Adrenergic activation increases glycogen synthesis in L6 skeletal muscle cells through a signalling pathway independent of cyclic AMP. Diabetologia 2007; 50:158-67. [PMID: 17119919 DOI: 10.1007/s00125-006-0484-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 09/01/2006] [Indexed: 01/05/2023]
Abstract
AIMS/HYPOTHESIS In skeletal muscle, the storage of glycogen by insulin is regulated by glycogen synthase, which is regulated by glycogen synthase kinase 3 (GSK3). Here we examined whether adrenergic receptor activation, which can increase glucose uptake, regulates glycogen synthesis in L6 skeletal muscle cells. METHODS We used L6 cells and measured glycogen synthesis (as incorporation of D: -[U-(14)C]glucose into glycogen) and GSK3 phosphorylation following adrenergic activation. RESULTS Insulin (negative logarithm of median effective concentration [pEC(50)] 8.2 +/- 0.3) and the beta-adrenergic agonist isoprenaline (pEC(50) 7.5 +/- 0.3) induced a twofold increase in glycogen synthesis in a concentration-dependent manner. The alpha(1)-adrenergic agonist cirazoline and alpha(2)-adrenergic agonist clonidine had no effect. Both insulin and isoprenaline phosphorylated GSK3. The beta-adrenergic effect on glycogen synthesis is mediated by beta(2)-adrenoceptors and not beta(1)-/beta(3)-adrenoceptors, and was not mimicked by 8-bromo-cyclic AMP or cholera toxin, and also was insensitive to pertussis toxin, indicating no involvement of cyclic AMP or inhibitory G-protein (G(i)) signalling in the beta(2)-adrenergic effect on glycogen synthesis. 12-O-tetra-decanoylphorbol-13-acetate (TPA) increased glycogen synthesis 2.5-fold and phosphorylated GSK3 fourfold. Inhibition of protein kinase C (PKC) isoforms with 12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrollo(3,4-c)-carbazole (Gö6976; inhibits conventional and novel PKCs) or 2-[1-(3-dimethylaminopropyl)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl)maleimide (Gö6983; inhibits conventional, novel and atypical PKCs) inhibited the stimulatory TPA effect, but did not significantly inhibit glycogen synthesis mediated by insulin or isoprenaline. Inhibition of phosphatidylinositol 3-kinase (PI3K) with wortmannin inhibited the effects of insulin and isoprenaline on glycogen synthesis. CONCLUSIONS/INTERPRETATION These results demonstrate that in L6 skeletal muscle cells adrenergic stimulation through beta(2)-adrenoceptors, but not involving cyclic AMP or G(i), activates a PI3K pathway that stimulates glycogen synthesis through GSK3.
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Affiliation(s)
- D L Yamamoto
- Department of Physiology, The Wenner-Gren Institute, Arrhenius Laboratories F3, Stockholm University, SE 10691, Stockholm, Sweden
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34
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Zeng ZZ, Jia Y, Hahn NJ, Markwart SM, Rockwood KF, Livant DL. Role of Focal Adhesion Kinase and Phosphatidylinositol 3′-Kinase in Integrin Fibronectin Receptor-Mediated, Matrix Metalloproteinase-1–Dependent Invasion by Metastatic Prostate Cancer Cells. Cancer Res 2006; 66:8091-9. [PMID: 16912186 DOI: 10.1158/0008-5472.can-05-4400] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
alpha(5)beta(1) Integrin interacts with the PHSRN sequence of plasma fibronectin, causing constitutive invasion by human prostate cancer cells. Inhibition of this process reduces tumorigenesis and prevents metastasis and recurrence. In this study, naturally serum-free basement membranes were used as in vitro invasion substrates. Immunoassays were employed to dissect the roles of focal adhesion kinase (FAK), phosphatidylinositol 3'-kinase (PI3K), and protein kinase Cdelta (PKC delta) in alpha(5)beta(1)-mediated, matrix metalloproteinase-1 (MMP-1)-dependent invasion by metastatic human DU 145 prostate cancer cells. We found that a peptide composed of the PHSRN sequence induced rapid FAK phosphorylation at Tyr(397) (Y397), a site whose phosphorylation is associated with kinase activation. The technique of RNA silencing [small interfering RNA (siRNA)] confirmed the role of FAK in PHSRN-induced invasion. PHSRN also induced the association of the p85-regulatory subunit of PI3K with FAK at a time corresponding to FAK phosphorylation and activation, and maximal PI3K activity occurred at this same time. The necessity of PI3K activity in both PHSRN-induced invasion and MMP-1 expression was confirmed by using specific PI3K inhibitors. By employing a specific inhibitor, Rottlerin, and by using siRNA, we also found that PKC delta, a PI3K substrate found in focal adhesions, functions in PHSRN-induced invasion. In addition, the induction of MMP-1 in PHSRN-treated DU 145 cells was shown by immunoblotting, and the role of MMP-1 in PHSRN-induced invasion was confirmed by the use of blocking anti-MMP-1 monoclonal antibody. Finally, a close temporal correspondence was observed between PHSRN-induced invasion and PHSRN-induced MMP-1 activity in DU 145 cells.
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Affiliation(s)
- Zhao-Zhu Zeng
- Department of Radiation Oncology and Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109-0582, USA
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35
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Nevzorova J, Evans BA, Bengtsson T, Summers RJ. Multiple signalling pathways involved in beta2-adrenoceptor-mediated glucose uptake in rat skeletal muscle cells. Br J Pharmacol 2006; 147:446-54. [PMID: 16415914 PMCID: PMC1616992 DOI: 10.1038/sj.bjp.0706626] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
1. Beta-adrenoceptor (AR) agonists increase 2-deoxy-[3H]-D-glucose uptake (GU) via beta2-AR in rat L6 cells. The beta-AR agonists, zinterol (beta2-AR) and (-)-isoprenaline, increased cAMP accumulation in a concentration-dependent manner (pEC50=9.1+/-0.02 and 7.8+/-0.02). Cholera toxin (% max increase 141.8+/-2.5) and the cAMP analogues, 8-bromo-cAMP (8Br-cAMP) and dibutyryl cAMP (dbcAMP), also increased GU (196.8+/-13.5 and 196.4+/-17.3%). 2. The adenylate cyclase inhibitor, 2',5'-dideoxyadenosine (50 microM), significantly reduced cAMP accumulation to zinterol (100 nM) (109.7+35.0 to 21.6+4.5 pmol well(-1)), or forskolin (10 microM) (230.1+/-58.0 to 107.2+/-26.3 pmol well(-1)), and partially inhibited zinterol-stimulated GU (217+/-26.3 to 176.1+/-20.4%). The protein kinase A (PKA) inhibitor, 4-cyano-3-methylisoquinoline (100 nM), did not inhibit zinterol-stimulated GU. The PDE4 inhibitor, rolipram (10 microM), increased cAMP accumulation to zinterol or forskolin, and sensitised the GU response to zinterol, indicating a stimulatory role of cAMP in GU. 3. cAMP accumulation studies indicated that the beta2-AR was desensitised by prolonged stimulation with zinterol, but not forskolin, whereas GU responses to zinterol increased with time, suggesting that receptor desensitisation may be involved in GU. Receptor desensitisation was not reversed by inhibition of PKA or Gi. 4. PTX pretreatment (100 ng ml(-1)) inhibited insulin or zinterol-stimulated but not 8Br-cAMP or dbcAMP-stimulated GU. The PI3K inhibitor, LY294002 (1 microM), inhibited insulin- (174.9+/-5.9 to 142.7+/-2.7%) and zinterol- (166.9+/-7.6 to 141.1+/-8.1%) but not 8 Br-cAMP-stimulated GU. In contrast to insulin, zinterol did not cause phosphorylation of Akt. 5. The results suggest that GU in L6 cells involves three mechanisms: (1) an insulin-dependent pathway involving PI3K, (2) a beta2-AR-mediated pathway involving both cAMP and PI3K, and (3) a receptor-independent pathway suggested by cAMP analogues that increase GU independently of PI3K. PKA appears to negatively regulate beta2-AR-mediated GU.
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Affiliation(s)
- Julia Nevzorova
- Department of Pharmacology, PO Box 13E, Monash University, Victoria 3800, Australia
| | - Bronwyn A Evans
- Department of Pharmacology, PO Box 13E, Monash University, Victoria 3800, Australia
| | - Tore Bengtsson
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Roger J Summers
- Department of Pharmacology, PO Box 13E, Monash University, Victoria 3800, Australia
- Author for correspondence:
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36
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Tao Y, Maegawa H, Ugi S, Ikeda K, Nagai Y, Egawa K, Nakamura T, Tsukada S, Nishio Y, Maeda S, Kashiwagi A. The transcription factor AP-2beta causes cell enlargement and insulin resistance in 3T3-L1 adipocytes. Endocrinology 2006; 147:1685-96. [PMID: 16373417 DOI: 10.1210/en.2005-1304] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have reported the association of variations in the activating protein-2beta (AP-2beta) transcription factor gene with type 2 diabetes. This gene was preferentially expressed in 3T3-L1 adipocytes in a differentiation stage-dependent manner, and preliminary experiments showed that subjects with the disease-susceptible allele showed stronger expression in adipose tissue than those without the susceptible allele. Thus, we overexpressed the AP-2beta gene in 3T3-L1 adipocytes to clarify whether AP-2beta might play a crucial role in the pathogenesis of type 2 diabetes through dysregulation of adipocyte function. In cells overexpressing AP-2beta, cells increased in size by accumulation of triglycerides accompanied by enhanced glucose uptake. On the contrary, suppression of AP-2beta expression by small interfering RNA inhibited glucose uptake. Enhancement of glucose uptake by AP-2beta overexpression was attenuated by inhibitors of phospholipase C (PLC) and atypical protein kinase Czeta/lambda (PKCzeta/lambda), but not by a phosphatidylinositol 3-kinase (PI3-K) inhibitor. Consistently, we found activation of PLC and atypical PKC, but not PI3-K, by AP-2beta expression. Furthermore, overexpression of PLCgamma enhanced glucose uptake, and this activation was inhibited by an atypical PKC inhibitor, suggesting that the enhanced glucose uptake may be mediated through PLC and atypical PKCzeta/lambda, but not PI3-K. Moreover, we observed the increased tyrosine phosphorylation of Grb2-associated binder-1 (Gab1) and its association with PLCgamma, indicating that Gab1 may be involved in AP-2beta-induced PLCgamma activation. Finally, AP-2beta overexpression was found to relate to the impaired insulin signaling. We propose that AP-2beta is a candidate gene for producing adipocyte hypertrophy and may relate to the abnormal characteristics of adipocytes observed in obesity.
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Affiliation(s)
- Yukari Tao
- Division of Endocrinology and Metabolism, Department of Medicine, Shiga University of Medical Science, Seta, Otsu, Japan
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37
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Hutchinson DS, Bengtsson T. AMP-activated protein kinase activation by adrenoceptors in L6 skeletal muscle cells: mediation by alpha1-adrenoceptors causing glucose uptake. Diabetes 2006; 55:682-90. [PMID: 16505231 DOI: 10.2337/diabetes.55.03.06.db05-0901] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AMP-activated protein kinase (AMPK), which functions as a sensor of cellular energy homeostasis, was phosphorylated after norepinephrine stimulation in L6 skeletal muscle cells. This effect was mediated by alpha1-adrenoceptors, with no stimulatory effects due to interactions at alpha2- or beta-adrenoceptors. Alpha1-adrenoceptors are Gq-coupled receptors, and calcium but not phorbol esters could mimic the effect of alpha1-adrenergic stimulation; and we show that protein kinase C is not involved as an upstream signal to AMPK by alpha1-adrenergic stimulation and that the AMP-to-ATP ratio is unaltered after alpha1-adrenergic stimulation. We further show that glucose uptake mediated by alpha1- but not by beta-adrenoceptors can be inhibited by AMPK inhibition. Acetyl-CoA carboxylase (ACC) is phosphorylated at Ser218 by AMPK, and alpha1- but not beta-adrenoceptor stimulation results in phosphorylation of ACC at this residue. These results suggest a novel pathway where alpha1-adrenoceptor activation, independent of protein kinase C, leads to activation of AMPK in skeletal muscle, which contributes to alpha1-adrenoceptor-mediated increases in glucose uptake.
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Affiliation(s)
- Dana S Hutchinson
- Department of Physiology, The Wenner-Gren Institute, Stockholm University, SE 10691 Stockholm, Sweden
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38
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Chernogubova E, Hutchinson DS, Nedergaard J, Bengtsson T. Alpha1- and beta1-adrenoceptor signaling fully compensates for beta3-adrenoceptor deficiency in brown adipocyte norepinephrine-stimulated glucose uptake. Endocrinology 2005; 146:2271-84. [PMID: 15665039 DOI: 10.1210/en.2004-1104] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To assess the relative roles and potential contribution of adrenergic receptor subtypes other than the beta3-adrenergic receptor in norepinephrine-mediated glucose uptake in brown adipocytes, we have here analyzed adrenergic activation of glucose uptake in primary cultures of brown adipocytes from wild-type and beta3-adrenergic receptor knockout (KO) mice. In control cells in addition to high levels of beta3-adrenergic receptor mRNA, there were relatively low alpha1A-, alpha1D-, and moderate beta1-adrenergic receptor mRNA levels with no apparent expression of other adrenergic receptors. The levels of alpha1A-, alpha1D-, and beta1-adrenergic receptor mRNA were not changed in the beta3-KO brown adipocytes, indicating that the beta3-adrenergic receptor ablation does not influence adrenergic gene expression in brown adipocytes in culture. As expected, the beta3-adrenergic receptor agonists BRL-37344 and CL-316 243 did not induce 2-deoxy-d-glucose uptake in beta3-KO brown adipocytes. Surprisingly, the endogenous adrenergic neurotransmitter norepinephrine induced the same concentration-dependent 2-deoxy-D-glucose uptake in wild-type and beta3-KO brown adipocytes. This study demonstrates that beta1-adrenergic receptors, and to a smaller degree alpha1-adrenergic receptors, functionally compensate for the lack of beta3-adrenergic receptors in glucose uptake. Beta1-adrenergic receptors activate glucose uptake through a cAMP/protein kinase A/phosphatidylinositol 3-kinase pathway, stimulating conventional and novel protein kinase Cs. The alpha1-adrenergic receptor component (that is not evident in wild-type cells) stimulates glucose uptake through a phosphatidylinositol 3-kinase and protein kinase C pathway in the beta3-KO cells.
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MESH Headings
- Adipocytes/chemistry
- Adipocytes/drug effects
- Adipocytes/metabolism
- Adipose Tissue, Brown/drug effects
- Adipose Tissue, Brown/metabolism
- Animals
- Blotting, Western
- Carrier Proteins/genetics
- Cells, Cultured
- Cyclic AMP/physiology
- Deoxyglucose/metabolism
- Gene Expression
- Glucose/metabolism
- Insulin/pharmacology
- Ion Channels
- Membrane Proteins/genetics
- Mice
- Mice, Knockout
- Mitochondrial Proteins
- Norepinephrine/pharmacology
- Phosphatidylinositol 3-Kinases/metabolism
- Protein Kinase C/metabolism
- RNA, Messenger/analysis
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/physiology
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-3/deficiency
- Receptors, Adrenergic, beta-3/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Uncoupling Protein 1
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Affiliation(s)
- Ekaterina Chernogubova
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, SE-106 91 Sweden
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