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Synthesis and Characterization of Novel Resveratrol Butyrate Esters That Have the Ability to Prevent Fat Accumulation in a Liver Cell Culture Model. Molecules 2020; 25:molecules25184199. [PMID: 32937766 PMCID: PMC7571132 DOI: 10.3390/molecules25184199] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/09/2020] [Accepted: 09/12/2020] [Indexed: 12/19/2022] Open
Abstract
To facilitate broad applications and enhance bioactivity, resveratrol was esterified to resveratrol butyrate esters (RBE). Esterification with butyric acid was conducted by the Steglich esterification method at room temperature with N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC) and 4-dimethyl aminopyridine (DMAP). Our experiments demonstrated the synthesis of RBE through EDC- and DMAP-facilitated esterification was successful and that the FTIR spectra of RBE revealed absorption (1751 cm−1) in the ester region. 13C-NMR spectrum of RBE showed a peak at 171 ppm corresponding to the ester group and peaks between 1700 and 1600 cm−1 in the FTIR spectra. RBE treatment (25 or 50 μM) decreased oleic acid-induced lipid accumulation in HepG2 cells. This effect was stronger than that of resveratrol and mediated through the downregulation of p-ACC and SREBP-2 expression. This is the first study demonstrating RBE could be synthesized by the Steglich method and that resulting RBE could inhibit lipid accumulation in HepG2 cells. These results suggest that RBE could potentially serve as functional food ingredients and supplements for health promotion.
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2
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A synbiotic consisting of Lactobacillus plantarum S58 and hull-less barley β-glucan ameliorates lipid accumulation in mice fed with a high-fat diet by activating AMPK signaling and modulating the gut microbiota. Carbohydr Polym 2020; 243:116398. [DOI: 10.1016/j.carbpol.2020.116398] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/19/2020] [Accepted: 04/28/2020] [Indexed: 02/08/2023]
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3
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Li Y, Li Y, Yang T, Wang M. Dioscin attenuates oxLDL uptake and the inflammatory reaction of dendritic cells under high glucose conditions by blocking p38 MAPK. Mol Med Rep 2019; 21:304-310. [PMID: 31746382 PMCID: PMC6896274 DOI: 10.3892/mmr.2019.10806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 10/15/2019] [Indexed: 12/26/2022] Open
Abstract
Dioscin has been shown to affect the regulation of metabolic diseases, including diabetes; however, the mechanism of action is still unclear. Under high glucose (HG) conditions, the expression of scavenger receptors and the uptake of oxidized low‑density lipoprotein (oxLDL) are upregulated in dendritic cells (DCs), which are critical steps in atherogenesis and inflammation. In this study, the focus was on the impact of dioscin on the function of DCs. Immature DCs were cultured with: 5.5 mM glucose medium (control group); 30 mM glucose medium (HG group); HG + 10 mM dioscin; HG + 20 mM dioscin; HG + 30 mM dioscin; and HG + 40 mM dioscin. For subsequent experiments, 30 mM dioscin was used as the experimental concentration. Dichlorodihydrofluorescein fluorescence was used to measure the intracellular production of reactive oxygen species (ROS) in DCs. The expression levels of the scavenger receptors, including class A scavenger receptors (SR‑A), CD36 and lectin‑like oxidized low‑density lipoprotein receptor‑1 (LOX‑1) were determined via quantitative PCR. The protein expression of p38 mitogen‑activated protein kinase (MAPK) was determined by western blotting. Furthermore, ELISA was used to detect the levels of interleukin (IL)‑6, IL‑10 and IL‑12. Finally, DCs were incubated with diOlistic (Dil)‑labeled oxLDL, and flow cytometry analysis was used to investigate the Dil‑oxLDL‑incorporated fraction. The incubation of DCs with dioscin inhibited the induction of ROS production, in a dose‑dependent manner, under HG conditions. The upregulation of SR‑A, CD36 and LOX‑1 genes was partially abolished by dioscin, which also partially reversed p38 MAPK protein upregulation. Furthermore, increased secretion of IL‑6 and IL‑12, and decreased secretion of IL‑10 in DCs, induced by HG, was also reversed by dioscin. To conclude, dioscin could attenuate the production of ROS, inflammatory cytokine secretion and oxLDL uptake by DCs in HG conditions by preventing the expression of scavenger receptors and p38 MAPK, thus playing a positive role in preventing atherogenesis.
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Affiliation(s)
- Ying Li
- Cardiovascular Department, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400011, P.R. China
| | - Yong Li
- Cardiovascular Department, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400011, P.R. China
| | - Te Yang
- Cardiovascular Department, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400011, P.R. China
| | - Ming Wang
- Cardiovascular Department, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400011, P.R. China
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Daniels LJ, Varma U, Annandale M, Chan E, Mellor KM, Delbridge LMD. Myocardial Energy Stress, Autophagy Induction, and Cardiomyocyte Functional Responses. Antioxid Redox Signal 2019; 31:472-486. [PMID: 30417655 DOI: 10.1089/ars.2018.7650] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Significance: Energy stress in the myocardium occurs in a variety of acute and chronic pathophysiological contexts, including ischemia, nutrient deprivation, and diabetic disease settings of substrate disturbance. Although the heart is highly adaptive and flexible in relation to fuel utilization and routes of adenosine-5'-triphosphate (ATP) generation, maladaptations in energy stress situations confer functional deficit. An understanding of the mechanisms that link energy stress to impaired myocardial performance is crucial. Recent Advances: Emerging evidence suggests that, in parallel with regulated enzymatic pathways that control intracellular substrate supply, other processes of "bulk" autophagic macromolecular breakdown may be important in energy stress conditions. Recent findings indicate that cargo-specific autophagic activity may be important in different stress states. In particular, induction of glycophagy, a glycogen-specific autophagy, has been described in acute and chronic energy stress situations. The impact of elevated cardiomyocyte glucose flux relating to glycophagy dysregulation on contractile function is unknown. Critical Issues: Ischemia- and diabetes-related cardiac adverse events comprise the majority of cardiovascular disease morbidity and mortality. Current therapies involve management of systemic comorbidities. Cardiac-specific adjunct treatments targeted to manage myocardial energy stress responses are lacking. Future Directions: New knowledge is required to understand the mechanisms involved in selective recruitment of autophagic responses in the cardiomyocyte energy stress response. In particular, exploration of the links between cell substrate flux, calcium ion (Ca2+) flux, and phagosomal cargo flux is required. Strategies to target specific fuel "bulk" management defects in cardiac energy stress states may be of therapeutic value.
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Affiliation(s)
- Lorna J Daniels
- 1 Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Upasna Varma
- 2 Department of Physiology, University of Melbourne, Melbourne, Australia
| | - Marco Annandale
- 1 Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Eleia Chan
- 2 Department of Physiology, University of Melbourne, Melbourne, Australia
| | - Kimberley M Mellor
- 1 Department of Physiology, University of Auckland, Auckland, New Zealand.,2 Department of Physiology, University of Melbourne, Melbourne, Australia.,3 Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Lea M D Delbridge
- 2 Department of Physiology, University of Melbourne, Melbourne, Australia
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Kim KY, Park KI, Lee SG, Baek SY, Lee EH, Kim SC, Kim SH, Park SG, Yu SN, Oh TW, Kim JH, Kim KJ, Ahn SC, Kim YW. Deoxypodophyllotoxin in Anthriscus sylvestris alleviates fat accumulation in the liver via AMP-activated protein kinase, impeding SREBP-1c signal. Chem Biol Interact 2018; 294:151-157. [PMID: 30148990 DOI: 10.1016/j.cbi.2018.08.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/17/2018] [Accepted: 08/23/2018] [Indexed: 01/21/2023]
Abstract
Deoxypodophyllotoxin (DPT) is a naturally occurring flavolignan in Anthriscus sylvestris known as cow parsley or wild chervil, and has been reported to have inhibitory effects against several pathological processes including cancer, inflammation and infection. Here, we report the effects of DPT in the fatty liver induced by high fat diet in vivo as well as its regulatory mechanism related with the transcription factor for lipogenic genes such as sterol regulatory element binding protein-1c (SREBP-1c) in vitro. C57BL/6 mice were fed high fat diet for 10 weeks and also orally administrated with DPT for additional 4 weeks. 5 and 10 mg/kg of DPT decreased lipid accumulation in the liver induced by high fat diet, as indicated by histological parameters such as Oil Red O staining and hematoxylin & eosin as well as the contents of hepatic triglyceride and cholesterol. In hepatocytes, DPT inhibited the liver X receptor α-mediated SREBP-1c induction and expression of the lipogenic genes, including fatty acid synthase, acetyl-CoA carboxylase and stearoyl-CoA desaturase-1. Moreover, DPT induced AMP-activated protein kinase (AMPK) activation, which has been known to inhibit the expression of SREBP-1c in hepatocyte. Also this compound restored the dysregulation of AMPK and SREBP-1c induced by high fat diet in mice. In conclusion, we demonstrated that DPT significantly inhibited fatty liver by adjusting lipid metabolism coordinated with AMPK activation and SREBP-1c inhibition.
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Affiliation(s)
- Kwang-Youn Kim
- Korean Medicine Application Center, Korea Institute of Oriental Medicine, Daegu, 41062, South Korea
| | - Kwang-Il Park
- Korean Medicine Application Center, Korea Institute of Oriental Medicine, Daegu, 41062, South Korea
| | - Seul Gi Lee
- Medical Research Center, Daegu Haany University, Gyeongsan, 38610, South Korea
| | - Su Youn Baek
- Medical Research Center, Daegu Haany University, Gyeongsan, 38610, South Korea
| | - Eun Hye Lee
- Medical Research Center, Daegu Haany University, Gyeongsan, 38610, South Korea
| | - Sang Chan Kim
- Medical Research Center, Daegu Haany University, Gyeongsan, 38610, South Korea
| | - Sang-Hun Kim
- Section of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Sul-Gi Park
- Department of Microbiology and Immunology, Pusan National University School of Medicine, Yangsan, 50612, South Korea
| | - Sun-Nyoung Yu
- Department of Microbiology and Immunology, Pusan National University School of Medicine, Yangsan, 50612, South Korea
| | - Tae Woo Oh
- Korean Medicine Application Center, Korea Institute of Oriental Medicine, Daegu, 41062, South Korea
| | - Joung-Hee Kim
- Department of Biomedical Laboratory Science, Daekyeung College, Gyeongsan, 38547, South Korea
| | - Keuk-Jun Kim
- Department of Biomedical Laboratory Science, Daekyeung College, Gyeongsan, 38547, South Korea
| | - Soon-Cheol Ahn
- Department of Microbiology and Immunology, Pusan National University School of Medicine, Yangsan, 50612, South Korea.
| | - Young Woo Kim
- Medical Research Center, Daegu Haany University, Gyeongsan, 38610, South Korea.
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Sun S, Gu Z, Fu H, Zhu J, Ge X, Wu X. Hypoxia Induces Changes in AMP-Activated Protein Kinase Activity and Energy Metabolism in Muscle Tissue of the Oriental River Prawn Macrobrachium nipponense. Front Physiol 2018; 9:751. [PMID: 29962970 PMCID: PMC6011032 DOI: 10.3389/fphys.2018.00751] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 05/28/2018] [Indexed: 12/18/2022] Open
Abstract
Hypoxia has important effects on biological activity in crustaceans, and modulation of energy metabolism is a crucial aspect of crustaceans’ ability to respond to hypoxia. The adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) enzyme is very important in cellular energy homeostasis; however, little information is known about the role of AMPK in the response of prawns to acute hypoxia. In the present study, three subunits of AMPK were cloned from the oriental river prawn, Macrobrachium nipponense. The full-length cDNAs of the α, β, and γ AMPK subunits were 1,837, 3,174, and 3,773 bp long, with open reading frames of 529, 289, and 961 amino acids, respectively. Primary amino acid sequence alignment of these three subunits revealed conserved similarity between the functional domains of the M. nipponense AMPK protein with AMPK proteins of other animals. The expression of the three AMPK subunits was higher in muscle tissue than in other tissues. Furthermore, the mRNA expression of AMPKα, AMPKβ, and AMPKγ were significantly up-regulated in M. nipponense muscle tissue after acute hypoxia. Probing with a phospho-AMPKα antibody revealed that AMPK is phosphorylated following hypoxia; this phosphorylation event was found to be essential for AMPK activation. Levels of glucose and lactic acid in hemolymph and muscle tissue were significantly changed over the course of hypoxia and recovery, indicating dynamic changes in energy metabolism in response to hypoxic stress. The activation of AMPK by hypoxic stress in M. nipponense was compared to levels of muscular AMP, ADP, and ATP, as determined by HPLC; it was found that activation of AMPK may not completely correlate with AMP:ATP ratios in prawns under hypoxic conditions. These findings confirm that the α, β, and γ subunits of the prawn AMPK protein are regulated at the transcriptional and protein levels during hypoxic stress to facilitate maintenance of energy homeostasis.
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Affiliation(s)
- Shengming Sun
- Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Centre, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Zhongbao Gu
- Guangxi Academy of Fishery Sciences, Nanning, China
| | - Hongtuo Fu
- Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Centre, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Jian Zhu
- Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Centre, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Xianping Ge
- Key Laboratory of Genetic Breeding and Aquaculture Biology of Freshwater Fishes, Ministry of Agriculture, Freshwater Fisheries Research Centre, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Xugan Wu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, China
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Modulation of hepatic inflammation and energy-sensing pathways in the rat liver by high-fructose diet and chronic stress. Eur J Nutr 2018; 58:1829-1845. [PMID: 29845385 DOI: 10.1007/s00394-018-1730-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 05/22/2018] [Indexed: 12/29/2022]
Abstract
PURPOSE High-fructose consumption and chronic stress are both associated with metabolic inflammation and insulin resistance. Recently, disturbed activity of energy sensor AMP-activated protein kinase (AMPK) was recognized as mediator between nutrient-induced stress and inflammation. Thus, we analyzed the effects of high-fructose diet, alone or in combination with chronic stress, on glucose homeostasis, inflammation and expression of energy sensing proteins in the rat liver. METHODS In male Wistar rats exposed to 9-week 20% fructose diet and/or 4-week chronic unpredictable stress we measured plasma and hepatic corticosterone level, indicators of glucose homeostasis and lipid metabolism, hepatic inflammation (pro- and anti-inflammatory cytokine levels, Toll-like receptor 4, NLRP3, activation of NFκB, JNK and ERK pathways) and levels of energy-sensing proteins AMPK, SIRT1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α). RESULTS High-fructose diet led to glucose intolerance, activation of NFκB and JNK pathways and increased intrahepatic IL-1β, TNFα and inhibitory phosphorylation of insulin receptor substrate 1 on Ser307. It also decreased phospho-AMPK/AMPK ratio and increased SIRT1 expression. Stress alone increased plasma and hepatic corticosterone but did not influence glucose tolerance, nor hepatic inflammatory or energy-sensing proteins. After the combined treatment, hepatic corticosterone was increased, glucose tolerance remained preserved, while hepatic inflammation was partially prevented despite decreased AMPK activity. CONCLUSION High-fructose diet resulted in glucose intolerance, hepatic inflammation, decreased AMPK activity and reduced insulin sensitivity. Chronic stress alone did not exert such effects, but when applied together with high-fructose diet it could partially prevent fructose-induced inflammation, presumably due to increased hepatic glucocorticoids.
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Yao H, Tao X, Xu L, Qi Y, Yin L, Han X, Xu Y, Zheng L, Peng J. Dioscin alleviates non-alcoholic fatty liver disease through adjusting lipid metabolism via SIRT1/AMPK signaling pathway. Pharmacol Res 2018; 131:51-60. [DOI: 10.1016/j.phrs.2018.03.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 03/19/2018] [Accepted: 03/20/2018] [Indexed: 02/09/2023]
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Xu C, Liu WB, Zhang DD, Wang KZ, Xia SL, Li XF. Molecular characterization of AMP-activated protein kinase α2 from herbivorous fish Megalobrama amblycephala and responsiveness to glucose loading and dietary carbohydrate levels. Comp Biochem Physiol A Mol Integr Physiol 2017; 208:24-34. [DOI: 10.1016/j.cbpa.2017.03.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 02/24/2017] [Accepted: 03/13/2017] [Indexed: 10/20/2022]
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Kido K, Yokokawa T, Ato S, Sato K, Fujita S. Effect of resistance exercise under conditions of reduced blood insulin on AMPKα Ser485/491 inhibitory phosphorylation and AMPK pathway activation. Am J Physiol Regul Integr Comp Physiol 2017; 313:R110-R119. [PMID: 28515080 DOI: 10.1152/ajpregu.00063.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/02/2017] [Accepted: 05/15/2017] [Indexed: 11/22/2022]
Abstract
Insulin stimulates skeletal muscle glucose uptake via activation of the protein kinase B/Akt (Akt) pathway. Recent studies suggest that insulin downregulates AMP-activated protein kinase (AMPK) activity via Ser485/491 phosphorylation of the AMPK α-subunit. Thus lower blood insulin concentrations may induce AMPK signal activation. Acute exercise is one method to stimulate AMPK activation; however, no study has examined the relationship between blood insulin levels and acute resistance exercise-induced AMPK pathway activation. Based on previous findings, we hypothesized that the acute resistance exercise-induced AMPK pathway activation would be augmented by disruptions in insulin secretion through a decrease in AMPKα Ser485/491 inhibitory phosphorylation. To test the hypothesis, 10-wk-old male Sprague-Dawley rats were administered the toxin streptozotocin (STZ; 55 mg/kg) to destroy the insulin secreting β-cells. Three days postinjection, the right gastrocnemius muscle from STZ and control rats was subjected to resistance exercise by percutaneous electrical stimulation. Animals were killed 0, 1, or 3 h later; activation of the Akt/AMPK and downstream pathways in the muscle tissue was analyzed by Western blotting and real-time PCR. Notably, STZ rats showed a significant decrease in basal Akt and AMPKα Ser485/491 phosphorylation, but substantial exercise-induced increases in both AMPKα Thr172 and acetyl-CoA carboxylase (ACC) Ser79 phosphorylation were observed. Although no significant impact on resistance exercise-induced Akt pathway activation or glucose uptake was found, resistance exercise-induced peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1 α (PGC-1α) gene expression was augmented by STZ treatment. Collectively, these data suggest that circulating insulin levels may regulate acute resistance exercise-induced AMPK pathway activation and AMPK-dependent gene expression relating to basal AMPKα Ser485/491 phosphorylation.
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Affiliation(s)
- Kohei Kido
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Takumi Yokokawa
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan; and
| | - Satoru Ato
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Koji Sato
- Graduate School of Human Development and Environment, Kobe University, Kobe, Hyogo, Japan
| | - Satoshi Fujita
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan;
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Salminen A, Kaarniranta K, Kauppinen A. Age-related changes in AMPK activation: Role for AMPK phosphatases and inhibitory phosphorylation by upstream signaling pathways. Ageing Res Rev 2016; 28:15-26. [PMID: 27060201 DOI: 10.1016/j.arr.2016.04.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/18/2016] [Accepted: 04/05/2016] [Indexed: 02/07/2023]
Abstract
AMP-activated protein kinase (AMPK) is a fundamental regulator of energy metabolism, stress resistance, and cellular proteostasis. AMPK signaling controls an integrated signaling network which is involved in the regulation of healthspan and lifespan e.g. via FoxO, mTOR/ULK1, CRCT-1/CREB, and SIRT1 signaling pathways. Several studies have demonstrated that the activation capacity of AMPK signaling declines with aging, which impairs the maintenance of efficient cellular homeostasis and enhances the aging process. However, it seems that the aging process affects AMPK activation in a context-dependent manner since occasionally, it can also augment AMPK activation, possibly attributable to the type of insult and tissue homeostasis. Three protein phosphatases, PP1, PP2A, and PP2C, inhibit AMPK activation by dephosphorylating the Thr172 residue of AMPKα, required for AMPK activation. In addition, several upstream signaling pathways can phosphorylate Ser/Thr residues in the β/γ interaction domain of the AMPKα subunit that subsequently blocks the activation of AMPK. These inhibitory pathways include the insulin/AKT, cyclic AMP/PKA, and RAS/MEK/ERK pathways. We will examine the evidence whether the efficiency of AMPK responsiveness declines during the aging process. Next, we will review the mechanisms involved in curtailing the activation of AMPK. Finally, we will elucidate the potential age-related changes in the inhibitory regulation of AMPK signaling that might be a part of the aging process.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, P.O. Box 100, FI-70029 KYS, Finland
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
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Van Caenegem O, Beauloye C, Bertrand L, Horman S, Lepropre S, Sparavier G, Vercruysse J, Bethuyne N, Poncelet AJ, Gianello P, Demuylder P, Legrand E, Beaurin G, Bontemps F, Jacquet LM, Vanoverschelde JL. Hypothermic continuous machine perfusion enables preservation of energy charge and functional recovery of heart grafts in an ex vivo model of donation following circulatory death. Eur J Cardiothorac Surg 2015; 49:1348-53. [PMID: 26604296 DOI: 10.1093/ejcts/ezv409] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/13/2015] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Cardiac transplantation using hearts from donors after circulatory death (DCD) is critically limited by the unavoidable warm ischaemia and its related unpredictable graft function. Inasmuch as hypothermic machine perfusion (MP) has been shown to improve heart preservation, we hypothesized that MP could enable the use of DCD hearts for transplantation. METHODS We recovered 16 pig hearts following anoxia-induced cardiac arrest and cardioplegia. Grafts were randomly assigned to two different groups of 4-h preservation using either static cold storage (CS) or MP (Modified LifePort© System, Organ Recovery Systems©, Itasca, Il). After preservation, the grafts were reperfused ex vivo using the Langendorff method for 60 min. Energetic charge was quantified at baseline, post-preservation and post-reperfusion by measuring lactate and high-energy phosphate levels. Left ventricular contractility parameters were assessed both in vivo prior to ischaemia and ex vivo during reperfusion. RESULTS Following preservation, the hearts that were preserved using CS exhibited higher lactate levels (57.1 ± 23.7 vs 21.4 ± 12.2 µmol/g; P < 0.001), increased adenosine monophosphate/adenosine triphosphate ratio (0.53 ± 0.25 vs 0.11 ± 0.11; P < 0.001) and lower phosphocreatine/creatine ratio (9.7 ± 5.3 vs 25.2 ± 11; P < 0.001) in comparison with the MP hearts. Coronary flow was similar in both groups during reperfusion (107 ± 9 vs 125 ± 9 ml/100 g/min heart; P = ns). Contractility decreased in the CS group, yet remained well preserved in the MP group. CONCLUSION MP preservation of DCD hearts results in improved preservation of the energy and improved functional recovery of heart grafts compared with CS.
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Affiliation(s)
- Olivier Van Caenegem
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium Cardiovascular Intensive Care, Cliniques universitaires Saint Luc, Brussels, Belgium
| | - Christophe Beauloye
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium Cardiovascular Intensive Care, Cliniques universitaires Saint Luc, Brussels, Belgium Division of Cardiology, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | - Luc Bertrand
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - Sandrine Horman
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - Sophie Lepropre
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - Grégory Sparavier
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | | | - Noëlla Bethuyne
- Division of Cardiac Surgery, Cliniques universitaires Saint Luc, Brussels, Belgium
| | - Alain J Poncelet
- Division of Cardiac Surgery, Cliniques universitaires Saint Luc, Brussels, Belgium Pôle de chirurgie expérimentale et transplantation, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - Pierre Gianello
- Pôle de chirurgie expérimentale et transplantation, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | | | - Eric Legrand
- Pôle de chirurgie expérimentale et transplantation, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - Gwen Beaurin
- Pôle de chirurgie expérimentale et transplantation, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium
| | - Françoise Bontemps
- Pôle de biochimie et recherche métabolique, Institut de Duve, Université catholique de Louvain, Brussels, Belgium
| | - Luc M Jacquet
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium Cardiovascular Intensive Care, Cliniques universitaires Saint Luc, Brussels, Belgium
| | - Jean-Louis Vanoverschelde
- Pôle de recherche cardiovasculaire, Institut de recherche expérimentale et clinique, Université catholique de Louvain, Brussels, Belgium Division of Cardiology, Cliniques universitaires Saint-Luc, Brussels, Belgium
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Insulin down-regulates the expression of ubiquitin E3 ligases partially by inhibiting the activity and expression of AMP-activated protein kinase in L6 myotubes. Biosci Rep 2015; 35:BSR20150017. [PMID: 26193886 PMCID: PMC4613693 DOI: 10.1042/bsr20150017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 07/13/2015] [Indexed: 02/06/2023] Open
Abstract
We conclude that insulin inhibits AMPK through Akt phosphorylation in L6 myotubes, which may serve as a possible signalling pathway for the down-regulation of protein degradation. Besides, decreased expression of AMPK α2 may partially participate in inhibiting the activity of AMPK. While insulin is an anabolic hormone, AMP-activated protein kinase (AMPK) is not only a key energy regulator, but it can also control substrate metabolism directly by inducing skeletal muscle protein degradation. The hypothesis of the present study was that insulin inhibits AMPK and thus down-regulates the expression of the ubiquitin E3 ligases, muscle atrophy F-box (MAFbx) and muscle RING finger 1 (MuRF1) in skeletal muscle cells. Differentiated L6 myotubes were treated with 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR) and/or compound C to stimulate and/or block AMPK respectively. These treatments were also conducted in the presence or absence of insulin and the cells were analysed by western blot and quantitative real-time PCR. In addition, nuleotide levels were determined using HPLC. The activation of AMPK with AICAR enhanced the mRNA levels of MAFbx and MuRF1. Insulin reduced the phosphorylation and activity AMPK, which was accompanied by reduced MAFbx and MuRF1 mRNA levels. Using a protein kinase B (PKB/Akt) inhibitor, we found that insulin regulates AMPK through the activation of Akt. Furthermore, insulin down-regulated AMPK α2 mRNA. We conclude that insulin inhibits AMPK through Akt phosphorylation in L6 myotubes, which may serve as a possible signalling pathway for the down-regulation of protein degradation. In addition, decreased expression of AMPK α2 may partially participate in inhibiting the activity of AMPK.
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Mechanical stretch activates mammalian target of rapamycin and AMP-activated protein kinase pathways in skeletal muscle cells. Mol Cell Biochem 2015; 406:285-92. [PMID: 25971373 DOI: 10.1007/s11010-015-2446-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 05/07/2015] [Indexed: 10/23/2022]
Abstract
Cellular protein synthesis is believed to be antagonistically regulated by mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) signaling pathways. In the present study, we examined the relationship between mTOR/p70 S6 kinase (p70S6K) and AMPK in response to mechanical stretch. C2C12 myoblasts were grown on a silicone elastomer chamber to confluence and further cultured in differentiation medium for 4 days to form multinucleated myotubes. Cells were subjected to 15% cyclic uniaxial stretch for 4 h at a frequency of 1 Hz. Phosphorylation of p70S6K at threonine 389 and AMPK at threonine 172 of the catalytic α subunit were concomitantly increased by mechanical stretch. Stimulation of the mTOR pathway by adding leucine and insulin increased the phosphorylation of p70S6K without inactivation of AMPK. In contrast, addition of compound C, a pharmacological inhibitor of AMPK, increased the phosphorylation of p70S6K in stretched cells. Activation of AMPK by the addition of 5-amino-4-imidazolecarboxamide ribonucleoside reduced the phosphorylation of p70S6K in response to mechanical stretch. In conclusion, crosstalk between mTOR and AMPK signaling was not tightly regulated in response to physiological stimuli, such as mechanical stress and/or nutrients. However, pharmacological modulation of AMPK influenced the mTOR/p70S6K signaling pathway.
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Abstract
The heart is a very special organ in the body and has a high requirement for metabolism due to its constant workload. As a consequence, to provide a consistent and sufficient energy a high steady-state demand of metabolism is required by the heart. When delicately balanced mechanisms are changed by physiological or pathophysiological conditions, the whole system's homeostasis will be altered to a new balance, which contributes to the pathologic process. So it is no wonder that almost every heart disease is related to metabolic shift. Furthermore, aging is also found to be related to the reduction in mitochondrial function, insulin resistance, and dysregulated intracellular lipid metabolism. Adenosine monophosphate-activated protein kinase (AMPK) functions as an energy sensor to detect intracellular ATP/AMP ratio and plays a pivotal role in intracellular adaptation to energy stress. During different pathology (like myocardial ischemia and hypertension), the activation of cardiac AMPK appears to be essential for repairing cardiomyocyte's function by accelerating ATP generation, attenuating ATP depletion, and protecting the myocardium against cardiac dysfunction and apoptosis. In this overview, we will talk about the normal heart's metabolism, how metabolic shifts during aging and different pathologies, and how AMPK regulates metabolic changes during these conditions.
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Affiliation(s)
- Yina Ma
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, NY 14214
| | - Ji Li
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, NY 14214
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López-Cotarelo P, Escribano-Díaz C, González-Bethencourt IL, Gómez-Moreira C, Deguiz ML, Torres-Bacete J, Gómez-Cabañas L, Fernández-Barrera J, Delgado-Martín C, Mellado M, Regueiro JR, Miranda-Carús ME, Rodríguez-Fernández JL. A novel MEK-ERK-AMPK signaling axis controls chemokine receptor CCR7-dependent survival in human mature dendritic cells. J Biol Chem 2014; 290:827-40. [PMID: 25425646 DOI: 10.1074/jbc.m114.596551] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Chemokine receptor CCR7 directs mature dendritic cells (mDCs) to secondary lymph nodes where these cells regulate the activation of T cells. CCR7 also promotes survival in mDCs, which is believed to take place largely through Akt-dependent signaling mechanisms. We have analyzed the involvement of the AMP-dependent kinase (AMPK) in the control of CCR7-dependent survival. A pro-apoptotic role for AMPK is suggested by the finding that pharmacological activators induce apoptosis, whereas knocking down of AMPK with siRNA extends mDC survival. Pharmacological activation of AMPK also induces apoptosis of mDCs in the lymph nodes. Stimulation of CCR7 leads to inhibition of AMPK, through phosphorylation of Ser-485, which was mediated by G(i)/Gβγ, but not by Akt or S6K, two kinases that control the phosphorylation of AMPK on Ser-485 in other settings. Using selective pharmacological inhibitors, we show that CCR7-induced phosphorylation of AMPK on Ser-485 is mediated by MEK and ERK. Coimmunoprecipitation analysis and proximity ligation assays indicate that AMPK associates with ERK, but not with MEK. These results suggest that in addition to Akt-dependent signaling mechanisms, CCR7 can also promote survival of mDCs through a novel MEK1/2-ERK1/2-AMPK signaling axis. The data also suggest that AMPK may be a potential target to modulate mDC lifespan and the immune response.
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Affiliation(s)
- Pilar López-Cotarelo
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - Cristina Escribano-Díaz
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | | | - Carolina Gómez-Moreira
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - María Laura Deguiz
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - Jesús Torres-Bacete
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - Laura Gómez-Cabañas
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - Jaime Fernández-Barrera
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - Cristina Delgado-Martín
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid
| | - Mario Mellado
- the CNB/CSIC (Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Cientificas,) 28049 Madrid
| | | | | | - José Luis Rodríguez-Fernández
- From the CIB/CSIC (Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas), 28040 Madrid,
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17
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Van Caenegem O, Beauloye C, Vercruysse J, Horman S, Bertrand L, Bethuyne N, Poncelet AJ, Gianello P, Demuylder P, Legrand E, Beaurin G, Bontemps F, Jacquet LM, Vanoverschelde JL. Hypothermic continuous machine perfusion improves metabolic preservation and functional recovery in heart grafts. Transpl Int 2014; 28:224-31. [PMID: 25265884 DOI: 10.1111/tri.12468] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/21/2014] [Accepted: 09/21/2014] [Indexed: 11/26/2022]
Abstract
The number of heart transplants is decreasing due to organ shortage, yet the donor pool could be enlarged by improving graft preservation. Hypothermic machine perfusion (MP) has been shown to improve kidney, liver, or lung graft preservation. Sixteen pig hearts were recovered following cardioplegia and randomized to two different groups of 4-hour preservation using either static cold storage (CS) or MP (Modified LifePort© System, Organ Recovery Systems, Itasca, Il). The grafts then underwent reperfusion on a Langendorff for 60 min. Energetic metabolism was quantified at baseline, postpreservation, and postreperfusion by measuring lactate and high-energy phosphates. The contractility index (CI) was assessed both in vivo prior to cardioplegia and during reperfusion. Following reperfusion, the hearts preserved using CS exhibited higher lactate levels (56.63 ± 23.57 vs. 11.25 ± 3.92 μmol/g; P < 0.001), increased adenosine monophosphate/adenosine triphosphate (AMP/ATP) ratio (0.4 ± 0.23 vs. 0.04 ± 0.04; P < 0.001), and lower phosphocreatine/creatine (PCr/Cr) ratio (33.5 ± 12.6 vs. 55.3 ± 5.8; P <0.001). Coronary flow was similar in both groups during reperfusion (107 ± 9 vs. 125 + /-9 ml/100 g/min heart; P = ns). CI decreased in the CS group, yet being well-preserved in the MP group. Compared with CS, MP resulted in improved preservation of the energy state and more successful functional recovery of heart graft.
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Affiliation(s)
- Olivier Van Caenegem
- Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
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18
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Valentine RJ, Coughlan KA, Ruderman NB, Saha AK. Insulin inhibits AMPK activity and phosphorylates AMPK Ser⁴⁸⁵/⁴⁹¹ through Akt in hepatocytes, myotubes and incubated rat skeletal muscle. Arch Biochem Biophys 2014; 562:62-9. [PMID: 25172224 DOI: 10.1016/j.abb.2014.08.013] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 08/15/2014] [Accepted: 08/18/2014] [Indexed: 01/16/2023]
Abstract
Recent studies have highlighted the importance of an inhibitory phosphorylation site, Ser(485/491), on the α-subunit of AMP-activated protein kinase (AMPK); however, little is known about the regulation of this site in liver and skeletal muscle. We examined whether the inhibitory effects of insulin on AMPK activity may be mediated through the phosphorylation of this inhibitory Ser(485/491) site in hepatocytes, myotubes and incubated skeletal muscle. HepG2 and C2C12 cells were stimulated with or without insulin for 15-min. Similarly, rat extensor digitorum longus (EDL) muscles were treated +/- insulin for 10-min. Insulin significantly increased Ser(485/491) p-AMPK under all conditions, resulting in a subsequent reduction in AMPK activity, ranging from 40% to 70%, despite no change in p-AMPK Thr(172). Akt inhibition both attenuated the increase in Ser(485/491) p-AMPK caused by insulin, and prevented the decrease in AMPK activity. Similarly, the growth factor IGF-1 stimulated Ser(485/491) AMPK phosphorylation, and this too was blunted by inhibition of Akt. Inhibition of the mTOR pathway with rapamycin, however, had no effect on insulin-stimulated Ser(485/491) p-AMPK. These data suggest that insulin and IGF-1 diminish AMPK activity in hepatocytes and muscle, most likely through Akt activation and the inhibitory phosphorylation of Ser(485/491) on its α-subunit.
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Affiliation(s)
- Rudy J Valentine
- Endocrinology, Diabetes, and Nutrition Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Kimberly A Coughlan
- Endocrinology, Diabetes, and Nutrition Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Neil B Ruderman
- Endocrinology, Diabetes, and Nutrition Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Asish K Saha
- Endocrinology, Diabetes, and Nutrition Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
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Involvement of the AMPK–PTEN pathway in insulin resistance induced by high glucose in cultured rat podocytes. Int J Biochem Cell Biol 2014; 51:120-30. [DOI: 10.1016/j.biocel.2014.04.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 03/28/2014] [Accepted: 04/09/2014] [Indexed: 11/17/2022]
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Shen Y, Honma N, Kobayashi K, Jia LN, Hosono T, Shindo K, Ariga T, Seki T. Cinnamon extract enhances glucose uptake in 3T3-L1 adipocytes and C2C12 myocytes by inducing LKB1-AMP-activated protein kinase signaling. PLoS One 2014; 9:e87894. [PMID: 24551069 PMCID: PMC3925101 DOI: 10.1371/journal.pone.0087894] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 01/04/2014] [Indexed: 12/31/2022] Open
Abstract
We previously demonstrated that cinnamon extract (CE) ameliorates type 1 diabetes induced by streptozotocin in rats through the up-regulation of glucose transporter 4 (GLUT4) translocation in both muscle and adipose tissues. This present study was aimed at clarifying the detailed mechanism(s) with which CE increases the glucose uptake in vivo and in cell culture systems using 3T3-L1 adipocytes and C2C12 myotubes in vitro. Specific inhibitors of key enzymes in insulin signaling and AMP-activated protein kinase (AMPK) signaling pathways, as well as small interference RNA, were used to examine the role of these kinases in the CE-induced glucose uptake. The results showed that CE stimulated the phosphorylation of AMPK and acetyl-CoA carboxylase. An AMPK inhibitor and LKB1 siRNA blocked the CE-induced glucose uptake. We also found for the first time that insulin suppressed AMPK activation in the adipocyte. To investigate the effect of CE on type 2 diabetes in vivo, we further performed oral glucose tolerance tests and insulin tolerance tests in type 2 diabetes model rats administered with CE. The CE improved glucose tolerance in oral glucose tolerance tests, but not insulin sensitivity in insulin tolerance test. In summary, these results indicate that CE ameliorates type 2 diabetes by inducing GLUT4 translocation via the AMPK signaling pathway. We also found insulin antagonistically regulates the activation of AMPK.
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Affiliation(s)
- Yan Shen
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Nihon University Graduate School of Bioresource Sciences, Kanagawa, Japan
| | - Natsumi Honma
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Nihon University Graduate School of Bioresource Sciences, Kanagawa, Japan
| | - Katsuya Kobayashi
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Nihon University Graduate School of Bioresource Sciences, Kanagawa, Japan
| | - Liu Nan Jia
- School of Pharmacy, Nihon University, Chiba, Japan
| | - Takashi Hosono
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Nihon University Graduate School of Bioresource Sciences, Kanagawa, Japan
- * E-mail:
| | - Kazutoshi Shindo
- Department of Food and Nutrition, Japan Women’s University, Tokyo, Japan
| | - Toyohiko Ariga
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Nihon University Graduate School of Bioresource Sciences, Kanagawa, Japan
| | - Taiichiro Seki
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Nihon University Graduate School of Bioresource Sciences, Kanagawa, Japan
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Muramatsu T, Yuasa K, Ebihara K, Shibukawa Y, Ohta K, Furusawa M, Shimono M. Glucose-free conditions induce the expression of AMPK in dental pulp cells. Arch Oral Biol 2013; 58:1603-8. [PMID: 24112725 DOI: 10.1016/j.archoralbio.2013.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 08/02/2013] [Accepted: 08/18/2013] [Indexed: 11/24/2022]
Abstract
OBJECTIVES This study is aimed to test whether glucose-free conditions induce the activation of adenosine monophosphate-activated protein kinase (AMPK) and, to investigate association with AMPK expression and cell viability in human dental pulp cells. DESIGN Human dental pulp cells were initially maintained in culture medium containing glucose and the medium was subsequently changed to glucose-free medium. To evaluate the expression of AMPK, quantitative real-time RT-PCR, Western blot analysis and immunofluorescence were carried out. Cell viability was evaluated by MTT assay. RESULTS The expression of AMPK mRNA in glucose free conditions was 2.0-2.5 fold higher than the control at 1, 2 and 3 h (P<0.01). The expression of phosphorylated-AMPK was characterized by Western blot analysis and by immunofluorescence. Compound C-pre-treated group showed a decline of both AMPK expression and cell viability, while AICAR-pre-treated group showed an increase of AMPK and maintain of cell viability at regular level. CONCLUSIONS AMPK plays an important role on fluctuating in accordance with glucose availability and protects cell viability from glucose free condition in human dental pulp cells.
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Affiliation(s)
- Takashi Muramatsu
- Oral Health Science Center hrc8, Tokyo Dental College, Chiba, Japan; Department of Endodontics and Clinical Cariology, Chiba, Japan; Department of Pathology, Tokyo Dental College, Chiba, Japan.
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Yu JW, Sun LJ, Liu W, Zhao YH, Kang P, Yan BZ. Hepatitis C virus core protein induces hepatic metabolism disorders through down-regulation of the SIRT1–AMPK signaling pathway. Int J Infect Dis 2013; 17:e539-45. [DOI: 10.1016/j.ijid.2013.01.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 12/17/2012] [Accepted: 01/31/2013] [Indexed: 12/23/2022] Open
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23
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Demeulder B, Zarrinpashneh E, Ginion A, Viollet B, Hue L, Rider MH, Vanoverschelde JL, Beauloye C, Horman S, Bertrand L. Differential regulation of eEF2 and p70S6K by AMPKalpha2 in heart. Biochim Biophys Acta Mol Basis Dis 2013; 1832:780-90. [DOI: 10.1016/j.bbadis.2013.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 02/17/2013] [Accepted: 02/25/2013] [Indexed: 01/13/2023]
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Tulipano G, Faggi L, Sibilia V, Giustina A. Points of integration between the intracellular energy sensor AMP-activated protein kinase (AMPK) activity and the somatotroph axis function. Endocrine 2012; 42:292-8. [PMID: 22736409 DOI: 10.1007/s12020-012-9732-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 06/14/2012] [Indexed: 12/21/2022]
Abstract
AMP-activated protein kinase (AMPK), an enzyme functioning as a cellular sensor of low energy, stores and promotes adaptive changes in growth, differentiation, and metabolism. While AMPK is primarily thought of as a regulator of systemic metabolism, it has been clearly established that it also has a role in the regulation of cell growth and may be a therapeutic target for proliferative disorders. Growth hormone (GH) secretion from the anterior pituitary and GH-induced synthesis and release of insulin-like-growth-factor-1 (IGF-1) from the liver determine linear growth before puberty. Actually, GH and IGF-1 are potent growth factors affecting cell growth and differentiation in different tissues, and still have anabolic functions and serve as essential regulators of fuel metabolism in adulthood, as well. A variety of peripheral hormonal and metabolic signals regulate GH secretion either by acting directly on the anterior pituitary and/or modulating GH-releasing hormone or somatostatin release from the hypothalamus. Actually, intracellular transduction of endocrine and metabolic signals regulating somatotroph function is still debated. Based on the previously summarized contents, the aim of the present work has been to review currently available data suggesting a role of AMPK in the interplay between GH axis activity and metabolic functions.
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Affiliation(s)
- Giovanni Tulipano
- Department of Biomedical Sciences and Biotechnologies, Unit of Pharmacology, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
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Augmenting muscle diacylglycerol and triacylglycerol content by blocking fatty acid oxidation does not impede insulin sensitivity. Proc Natl Acad Sci U S A 2012; 109:11711-6. [PMID: 22753483 DOI: 10.1073/pnas.1206868109] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A low fat oxidative capacity has been linked to muscle diacylglycerol (DAG) accumulation and insulin resistance. Alternatively, a low fat oxidation rate may stimulate glucose oxidation, thereby enhancing glucose disposal. Here, we investigated whether an ethyl-2-[6-(4-chlorophenoxy)hexyl]-oxirane-2-carboxylate (etomoxir)-induced inhibition of fat oxidation leads to muscle fat storage and insulin resistance. An intervention in healthy male subjects was combined with studies in human primary myotubes. Furthermore, muscle DAG and triacylglycerol (TAG), mitochondrial function, and insulin signaling were examined in etomoxir-treated C57bl6 mice. In humans, etomoxir administration increased glucose oxidation at the expense of fat oxidation. This effect was accompanied by an increased abundance of GLUT4 at the sarcolemma and a lowering of plasma glucose levels, indicative of improved glucose homeostasis. In mice, etomoxir injections resulted in accumulation of muscle TAG and DAG, yet improved insulin-stimulated GLUT4 translocation. Also in human myotubes, insulin signaling was improved by etomoxir, in the presence of increased intramyocellular lipid accumulation. These insulin-sensitizing effects in mice and human myotubes were accompanied by increased phosphorylation of AMP-activated protein kinase (AMPK). Our results show that a reduction in fat oxidation leading to accumulation of muscle DAG does not necessarily lead to insulin resistance, as the reduction in fat oxidation may activate AMPK.
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Song P, Zou MH. Regulation of NAD(P)H oxidases by AMPK in cardiovascular systems. Free Radic Biol Med 2012; 52:1607-19. [PMID: 22357101 PMCID: PMC3341493 DOI: 10.1016/j.freeradbiomed.2012.01.025] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 01/25/2012] [Accepted: 01/27/2012] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are ubiquitously produced in cardiovascular systems. Under physiological conditions, ROS/RNS function as signaling molecules that are essential in maintaining cardiovascular function. Aberrant concentrations of ROS/RNS have been demonstrated in cardiovascular diseases owing to increased production or decreased scavenging, which have been considered common pathways for the initiation and progression of cardiovascular diseases such as atherosclerosis, hypertension, (re)stenosis, and congestive heart failure. NAD(P)H oxidases are primary sources of ROS and can be induced or activated by all known cardiovascular risk factors. Stresses, hormones, vasoactive agents, and cytokines via different signaling cascades control the expression and activity of these enzymes and of their regulatory subunits. But the molecular mechanisms by which NAD(P)H oxidase is regulated in cardiovascular systems remain poorly characterized. Investigations by us and others suggest that adenosine monophosphate-activated protein kinase (AMPK), as an energy sensor and modulator, is highly sensitive to ROS/RNS. We have also obtained convincing evidence that AMPK is a physiological suppressor of NAD(P)H oxidase in multiple cardiovascular cell systems. In this review, we summarize our current understanding of how AMPK functions as a physiological repressor of NAD(P)H oxidase.
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Affiliation(s)
| | - Ming-Hui Zou
- To whom correspondence should be addressed: Ming-Hui Zou, M.D., Ph.D., Department of Medicine, University of Oklahoma Health Science Center, 941 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA, Phone: 405-271-3974, Fax: 405-271-3973,
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Islam A, Civitarese AE, Hesslink RL, Gallaher DD. Viscous dietary fiber reduces adiposity and plasma leptin and increases muscle expression of fat oxidation genes in rats. Obesity (Silver Spring) 2012; 20:349-55. [PMID: 22095115 DOI: 10.1038/oby.2011.341] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Dietary interventions that reduce accumulation of body fat are of great interest. Consumption of viscous dietary fibers cause well-known positive metabolic effects, such as reductions in the postprandial glucose and insulin concentrations. However, their effect on body composition and fuel utilization has not been previously studied. To examine this, rats were fed a viscous nonfermentable dietary fiber, hydroxypropyl methylcellulose (HPMC), for 6 weeks. Body composition was measured by dual-energy X-ray absorptiometry (DXA) and fat pad weight. Plasma adipokines, AMP kinase activation, and enzyme and mRNA analysis of key regulators of energetics in liver and soleus muscle were measured. The HPMC diet significantly lowered percent body fat mass and increased percent lean body mass, compared to a cellulose-containing diet (no viscosity). Fasting leptin was reduced 42% and resistin 28% in the HPMC group compared to the cellulose group. Rats fed HPMC had greater activation of AMP kinase in liver and muscle and lower phosphoenolpyruvate carboxykinase (PEPCK) expression in liver. mRNA expression in skeletal muscle was significantly increased for carnitine palmitoyltransferase 1B (CPT-1B), PPARγ coactivator 1α, PPARδ and uncoupling protein 3 (UCP3), as was citrate synthase (CS) activity, in the HPMC group relative to the cellulose group. These results indicate that viscous dietary fiber preserves lean body mass and reduces adiposity, possibly by increasing mitochondrial biogenesis and fatty acid oxidation in skeletal muscle, and thus represents a metabolic effect of viscous fiber not previously described. Thus, viscous dietary fiber may be a useful dietary component to assist in reduction of body fat.
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Affiliation(s)
- Ajmila Islam
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA
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Beauloye C, Bertrand L, Horman S, Hue L. AMPK activation, a preventive therapeutic target in the transition from cardiac injury to heart failure. Cardiovasc Res 2011; 90:224-33. [PMID: 21285292 DOI: 10.1093/cvr/cvr034] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Heart failure is a progressive muscular disorder leading to a deterioration of the heart characterized by a contractile dysfunction and a chronic energy deficit. As a consequence, the failing heart is unable to meet the normal metabolic and energy needs of the body. The transition between compensated left ventricular hypertrophy and the de-compensated heart is multifactorial, although metabolic disturbances are considered to play a significant role. In this respect, the AMP-activated protein kinase (AMPK) could be a potential target in heart failure development. AMPK senses the energy state of the cell and orchestrates a global metabolic response to energy deprivation. We briefly review here the current knowledge about the chronic energy deficit of the failing heart, as well as the role of AMPK in energy homeostasis and in the control of non-metabolic targets in relation to cardiac hypertrophy and heart failure. The relative importance of energetic and non-metabolic effects in the potential cardioprotective action of AMPK is discussed.
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Affiliation(s)
- Christophe Beauloye
- Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardio-Vasculaire, Université catholique de Louvain, Brussels, Belgium
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Howell NJ, Ashrafian H, Drury NE, Ranasinghe AM, Contractor H, Isackson H, Calvert M, Williams LK, Freemantle N, Quinn DW, Green D, Frenneaux M, Bonser RS, Mascaro JG, Graham TR, Rooney SJ, Wilson IC, Pagano D. Glucose-insulin-potassium reduces the incidence of low cardiac output episodes after aortic valve replacement for aortic stenosis in patients with left ventricular hypertrophy: results from the Hypertrophy, Insulin, Glucose, and Electrolytes (HINGE) trial. Circulation 2011; 123:170-7. [PMID: 21200004 DOI: 10.1161/circulationaha.110.945170] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Patients undergoing aortic valve replacement for critical aortic stenosis often have significant left ventricular hypertrophy. Left ventricular hypertrophy has been identified as an independent predictor of poor outcome after aortic valve replacement as a result of a combination of maladaptive myocardial changes and inadequate myocardial protection at the time of surgery. Glucose-insulin-potassium (GIK) is a potentially useful adjunct to myocardial protection. This study was designed to evaluate the effects of GIK infusion in patients undergoing aortic valve replacement surgery. METHODS AND RESULTS Patients undergoing aortic valve replacement for aortic stenosis with evidence of left ventricular hypertrophy were randomly assigned to GIK or placebo. The trial was double-blind and conducted at a single center. The primary outcome was the incidence of low cardiac output syndrome. Left ventricular biopsies were analyzed to assess changes in 5' adenosine monophosphate-activated protein kinase (AMPK), Akt phosphorylation, and protein O-linked β-N-acetylglucosamination (O-GlcNAcylation). Over a 4-year period, 217 patients were randomized (107 control, 110 GIK). GIK treatment was associated with a significant reduction in the incidence of low cardiac output state (odds ratio, 0.22; 95% confidence interval, 0.10 to 0.47; P=0.0001) and a significant reduction in inotrope use 6 to 12 hours postoperatively (odds ratio, 0.30; 95% confidence interval, 0.15 to 0.60; P=0.0007). These changes were associated with a substantial increase in AMPK and Akt phosphorylation and a significant increase in the O-GlcNAcylation of selected protein bands. CONCLUSIONS Perioperative treatment with GIK was associated with a significant reduction in the incidence of low cardiac output state and the need for inotropic support. This benefit was associated with increased signaling protein phosphorylation and O-GlcNAcylation. Multicenter studies and late follow-up will determine whether routine use of GIK improves patient prognosis.
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Affiliation(s)
- Neil J Howell
- Department of Cardiothoracic Surgery, University Hospital Birmingham, Edgbaston, Birmingham, UK
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Gonzalez CD, Lee MS, Marchetti P, Pietropaolo M, Towns R, Vaccaro MI, Watada H, Wiley JW. The emerging role of autophagy in the pathophysiology of diabetes mellitus. Autophagy 2011; 7:2-11. [PMID: 20935516 PMCID: PMC3359481 DOI: 10.4161/auto.7.1.13044] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Revised: 05/24/2010] [Accepted: 07/13/2010] [Indexed: 12/24/2022] Open
Abstract
An emerging body of evidence supports a role for autophagy in the pathophysiology of type 1 and type 2 diabetes mellitus. Persistent high concentrations of glucose lead to imbalances in the antioxidant capacity within the cell resulting in oxidative stress-mediated injury in both disorders. An anticipated consequence of impaired autophagy is the accumulation of dysfunctional organelles such as mitochondria within the cell. Mitochondria are the primary site of the production of reactive oxygen species (ROS), and an imbalance in ROS production relative to the cytoprotective action of autophagy may lead to the accumulation of ROS. Impaired mitochondrial function associated with increased ROS levels have been proposed as mechanisms contributing to insulin resistance. In this article we review and interpret the literature that implicates a role for autophagy in the pathophysiology of type 1 and type 2 diabetes mellitus as it applies to β-cell dysfunction, and more broadly to organ systems involved in complications of diabetes including the cardiovascular, renal and nervous systems.
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Affiliation(s)
- Claudio D Gonzalez
- Department of Pharmacology, CEMIC University Hospital and University of Buenos Aires, Buenos Aires, Argentina
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31
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Growth restriction before and after birth increases kinase signaling pathways in the adult rat heart. J Dev Orig Health Dis 2010; 1:376-85. [DOI: 10.1017/s2040174410000607] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Viollet B, Horman S, Leclerc J, Lantier L, Foretz M, Billaud M, Giri S, Andreelli F. AMPK inhibition in health and disease. Crit Rev Biochem Mol Biol 2010; 45:276-95. [PMID: 20522000 DOI: 10.3109/10409238.2010.488215] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All living organisms depend on dynamic mechanisms that repeatedly reassess the status of amassed energy, in order to adapt energy supply to demand. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals managing energy balance. Control of AMPK activity involves allosteric AMP and ATP regulation, auto-inhibitory features and phosphorylation of its catalytic (alpha) and regulatory (beta and gamma) subunits. AMPK has a prominent role not only as a peripheral sensor but also in the central nervous system as a multifunctional metabolic regulator. AMPK represents an ideal second messenger for reporting cellular energy state. For this reason, activated AMPK acts as a protective response to energy stress in numerous systems. However, AMPK inhibition also actively participates in the control of whole body energy homeostasis. In this review, we discuss recent findings that support the role and function of AMPK inhibition under physiological and pathological states.
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Affiliation(s)
- Benoit Viollet
- Institut Cochin, Université Paris Descartes, CNRS UMR 8104, Paris, France.
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The pivotal role of protein kinase C zeta (PKCzeta) in insulin- and AMP-activated protein kinase (AMPK)-mediated glucose uptake in muscle cells. Cell Signal 2010; 22:1513-22. [PMID: 20570724 DOI: 10.1016/j.cellsig.2010.05.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 05/28/2010] [Accepted: 05/29/2010] [Indexed: 11/20/2022]
Abstract
Insulin and AMP-activated protein kinase (AMPK) signal pathways are involved in the regulation of glucose uptake. The integration of signals between these two pathways to maintain glucose homeostasis remains elusive. In this work, stimulation of insulin and berberine conferred a glucose uptake or surface glucose transporter 4 (GLUT4) translocation that was less than simple summation of their effects in insulin-sensitive muscle cells. Using specific inhibitors to key kinases of both pathways and PKCzeta small interference RNA, protein kinase C zeta (PKCzeta) was found to regulate insulin-stimulated protein kinase B (PKB) activation and inhibit AMPK activity on dorsal cell surface. In the presence of berberine, PKCzeta controlled AMPK activation and AMPK blocked PKB activity in perinuclear region. The inhibition effect of PKCzeta on AMPK activation or the arrestment of PKB activity by AMPK still existed in basal condition. These results suggest that there is antagonistic regulation between insulin and AMPK signal pathways, which is mediated by the switch roles of PKCzeta.
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Lotz C, Fisslthaler B, Redel A, Smul TM, Stumpner J, Pociej J, Roewer N, Fleming I, Kehl F, Lange M. Activation of adenosine-monophosphate-activated protein kinase abolishes desflurane-induced preconditioning against myocardial infarction in vivo. J Cardiothorac Vasc Anesth 2010; 25:66-71. [PMID: 20456976 DOI: 10.1053/j.jvca.2010.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Myocardial ischemia is accompanied by a rapid activation of adenosine-monophosphate-activated protein kinase (AMPK). However, it is unclear whether this represents a potentially beneficial or detrimental event in the course of ischemic injury. The role of AMPK activation in the cardioprotective setting of desflurane-induced preconditioning has not been investigated to date. Hence, the current study was undertaken to address the role of AMPK activation during desflurane-induced preconditioning in vivo. DESIGN A prospective randomized vehicle-controlled study. SETTING A university research laboratory. SUBJECTS Male New Zealand white rabbits (n = 44). INTERVENTIONS The animals were subjected to a 30-minute coronary artery occlusion (CAO) followed by 3 hours of reperfusion. Desflurane (1.0 minimum alveolar concentration) was administered for 30 minutes and discontinued 30 minutes prior to CAO. Different groups of animals received the AMPK activator, 5-aminoimidazole-4-carboxamide-1-b-riboside (AICAR), alone or in combination with desflurane. Infarct size was determined gravimetrically; AMPK activity and myocardial glycogen content were measured using specific assays. Phosphorylation of the AMPK substrate, acetyl-CoA carboxylase, was assessed by immunoblotting. Data are mean ± standard error of the mean. RESULTS Desflurane significantly reduced the myocardial infarct size (36.7 ± 1.9%, p < 0.05) compared with the control group (61.6% ± 3.0%), concomitant with increased myocardial tissue levels of glycogen (2.09 ± 0.07 μg, p < 0.05). Activation of the AMPK by AICAR alone did not protect against ischemic injury (65% ± 3.3), but did abolish the cardioprotection elicited by desflurane (61.8% ± 4.2%) at the same time as increasing myocardial glycogen consumption (1.42 ± 0.15 μg/mL). CONCLUSIONS The results obtained show that the pharmacologic activation of AMPK abolishes cardioprotection elicited by desflurane.
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Affiliation(s)
- Christopher Lotz
- Department of Anesthesiology, Bayerische Julius-Maximilians-Universitaet, Würzburg, Germany
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Guerra B, Guadalupe-Grau A, Fuentes T, Ponce-González JG, Morales-Alamo D, Olmedillas H, Guillén-Salgado J, Santana A, Calbet JAL. SIRT1, AMP-activated protein kinase phosphorylation and downstream kinases in response to a single bout of sprint exercise: influence of glucose ingestion. Eur J Appl Physiol 2010; 109:731-43. [PMID: 20217115 DOI: 10.1007/s00421-010-1413-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2010] [Indexed: 11/29/2022]
Abstract
This study was designed to examine potential in vivo mechanisms of AMP-activated protein kinase (AMPK) phosphorylation inhibition and its downstream signaling consequences during the recovery period after a single bout of sprint exercise. Sprint exercise induces Thr(172)-AMPK phosphorylation and increased PGC-1alpha mRNA, by an unknown mechanism. Muscle biopsies were obtained in 15 young healthy men in response to a 30-s sprint exercise (Wingate test) randomly distributed into two groups: the fasting (n = 7, C) and the glucose group (n = 8, G), who ingested 75 g of glucose 1 h before exercising to inhibit AMPKalpha phosphorylation. Exercise elicited different patterns of Ser(221)-ACCbeta, Ser(473)-Akt and Thr(642)-AS160 phosphorylation, during the recovery period after glucose ingestion. Thirty minutes after the control sprint, Ser(485)-AMPKalpha1/Ser(491)-AMPKalpha2 phosphorylation was reduced by 33% coinciding with increased Thr(172)-AMPKalpha phosphorylation (both, P < 0.05). Glucose abolished the 30-min Thr(172)-AMPKalpha phosphorylation. Ser(221)-ACCbeta phosphorylation was elevated immediately following and 30 min after exercise in C and G, implying a dissociation between Thr(172)-AMPKalpha and Ser(221)-ACCbeta phosphorylation. Two hours after the sprint, PGC-1alpha protein expression remained unchanged while SIRT1 (its upstream deacetylase) was increased. Glucose ingestion abolished the SIRT1 response without any significant effect on PGC-1alpha protein expression. In conclusion, glucose ingestion prior to a sprint exercise profoundly affects Thr(172)-AMPKalpha phosphorylation and its downstream signaling during the recovery period.
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Affiliation(s)
- Borja Guerra
- Department of Physical Education, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017, Las Palmas de Gran Canaria, Canary Islands, Spain
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Lopaschuk GD, Ussher JR, Folmes CDL, Jaswal JS, Stanley WC. Myocardial fatty acid metabolism in health and disease. Physiol Rev 2010; 90:207-58. [PMID: 20086077 DOI: 10.1152/physrev.00015.2009] [Citation(s) in RCA: 1420] [Impact Index Per Article: 101.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
There is a constant high demand for energy to sustain the continuous contractile activity of the heart, which is met primarily by the beta-oxidation of long-chain fatty acids. The control of fatty acid beta-oxidation is complex and is aimed at ensuring that the supply and oxidation of the fatty acids is sufficient to meet the energy demands of the heart. The metabolism of fatty acids via beta-oxidation is not regulated in isolation; rather, it occurs in response to alterations in contractile work, the presence of competing substrates (i.e., glucose, lactate, ketones, amino acids), changes in hormonal milieu, and limitations in oxygen supply. Alterations in fatty acid metabolism can contribute to cardiac pathology. For instance, the excessive uptake and beta-oxidation of fatty acids in obesity and diabetes can compromise cardiac function. Furthermore, alterations in fatty acid beta-oxidation both during and after ischemia and in the failing heart can also contribute to cardiac pathology. This paper reviews the regulation of myocardial fatty acid beta-oxidation and how alterations in fatty acid beta-oxidation can contribute to heart disease. The implications of inhibiting fatty acid beta-oxidation as a potential novel therapeutic approach for the treatment of various forms of heart disease are also discussed.
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Affiliation(s)
- Gary D Lopaschuk
- Cardiovascular Research Group, Mazankowski Alberta Heart Institute, University of Alberta, Alberta T6G 2S2, Canada.
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Yue P, Jin H, Aillaud M, Deng AC, Azuma J, Asagami T, Kundu RK, Reaven GM, Quertermous T, Tsao PS. Apelin is necessary for the maintenance of insulin sensitivity. Am J Physiol Endocrinol Metab 2010; 298:E59-67. [PMID: 19861585 PMCID: PMC2806109 DOI: 10.1152/ajpendo.00385.2009] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The recently discovered peptide apelin is known to be involved in the maintenance of insulin sensitivity. However, questions persist regarding its precise role in the chronic setting. Fasting glucose, insulin, and adiponectin levels were determined on mice with generalized deficiency of apelin (APKO). Additionally, insulin (ITT) and glucose tolerance tests (GTT) were performed. To assess the impact of exogenously delivered apelin on insulin sensitivity, osmotic pumps containing pyroglutamated apelin-13 or saline were implanted in APKO mice for 4 wk. Following the infusion, ITT/GTTs were repeated and the animals euthanized. Soleus muscles were harvested and homogenized in lysis buffer, and insulin-induced Akt phosphorylation was determined by Western blotting. Apelin-13 infusion and ITTs/GTTs were also performed in obese diabetic db/db mice. To probe the underlying mechanism for apelin's effects, apelin-13 was also delivered to cultured C2C12 myotubes. 2-[3H]deoxyglucose uptake and Akt phosphorylation were assessed in the presence of various inhibitors. APKO mice had diminished insulin sensitivity, were hyperinsulinemic, and had decreased adiponectin levels. Soleus lysates had decreased insulin-induced Akt phosphorylation. Administration of apelin to APKO and db/db mice resulted in improved insulin sensitivity. In C2C12 myotubes, apelin increased glucose uptake and Akt phosphorylation. These events were fully abrogated by pertussis toxin, compound C, and siRNA knockdown of AMPKalpha1 but only partially diminished by LY-294002 and not at all by L-NAME. We conclude that apelin is necessary for the maintenance of insulin sensitivity in vivo. Apelin's effects on glucose uptake and Akt phosphorylation are in part mediated by a G(i) and AMPK-dependent pathway.
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Affiliation(s)
- Patrick Yue
- Div. of Cardiovascular Medicine, Stanford University School of Medicine, 300 Pasteur Dr., Falk CVRC, Stanford, CA 94305-5406, USA.
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Lamberts RR, Onderwater G, Hamdani N, Vreden MJA, Steenhuisen J, Eringa EC, Loer SA, Stienen GJM, Bouwman RA. Reactive oxygen species-induced stimulation of 5'AMP-activated protein kinase mediates sevoflurane-induced cardioprotection. Circulation 2009; 120:S10-5. [PMID: 19752353 DOI: 10.1161/circulationaha.108.828426] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND 5'AMP-activated protein kinase (AMPK), a well-known regulator of cellular energy status, is also implicated in ischemic preconditioning leading to cardioprotection. We hypothesized that AMPK is involved in anesthetic-induced cardioprotection and that this activation is mediated by reactive oxygen species (ROS). METHODS AND RESULTS Isolated Langendorff-perfused rat hearts were subjected to 35 minutes of global ischemia (I) followed by 120 minutes of reperfusion (I/R). Hearts were assigned to a control group (Con) or a sevoflurane (Sevo) group receiving 3 times 5-minute episodes of sevoflurane (2.5vol%) before I/R. Phosphorylation of both AMPK and endothelial nitric oxide synthase (eNOS) were determined by Western blot analysis. Cardioprotection was assessed after I/R from recovery of left ventricular pressure and from infarct size (triphenyltetrazolium chloride staining). In the control group, ischemia resulted in a 2-fold increase in phosphorylation levels of AMPK (Con 0.13+/-0.01 versus Con-I 0.28+/-0.05, P<0.05), which was sustained after 120 minutes of reperfusion (Con-I/R 0.26+/-0.02, P<0.05). Sevoflurane preconditioning had no affect on AMPK phosphorylation before ischemia (Sevo 0.12+/-0.03, P>0.05), but almost doubled the increase in AMPK phosphorylation relative to control after ischemia (Sevo-I 0.48+/-0.09, P<0.05), an effect that was sustained after reperfusion (Sevo-I/R 0.49+/-0.12, P<0.05). The AMPK-inhibitor compound C (10 micromol/L) reduced the sevoflurane-mediated increase in phosphorylation of AMPK and its target eNOS and abolished cardioprotection. The ROS-scavenger n-(2-mercaptopropionyl)-glycine (1 mmol/L) blunted the sevoflurane-mediated increase in AMPK and eNOS phosphorylation and prevented cardioprotection. CONCLUSIONS Sevoflurane-induced AMPK activation protects the heart against ischemia and reperfusion injury and relies on upstream production of ROS.
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Affiliation(s)
- Regis R Lamberts
- Department of Anesthesiology, VU University Medical Center, Amsterdam, The Netherlands.
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Abstract
The function and survival of all organisms is dependent on the dynamic control of energy metabolism, when energy demand is matched to energy supply. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals that control energy balance through the regulation of multiple biochemical pathways in all eukaryotes. In this review, we begin with the discovery of the AMPK family and discuss the recent structural studies that have revealed the molecular basis for AMP binding to the enzyme's gamma subunit. AMPK's regulation involves autoinhibitory features and phosphorylation of both the catalytic alpha subunit and the beta-targeting subunit. We review the role of AMPK at the cellular level through examination of its many substrates and discuss how it controls cellular energy balance. We look at how AMPK integrates stress responses such as exercise as well as nutrient and hormonal signals to control food intake, energy expenditure, and substrate utilization at the whole body level. Lastly, we review the possible role of AMPK in multiple common diseases and the role of the new age of drugs targeting AMPK signaling.
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Affiliation(s)
- Gregory R Steinberg
- Protein Chemistry and Metabolism, St. Vincent's Institute of Medical Research, University of Melbourne, Fitzroy, Victoria, Australia.
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Gurusamy N, Das DK. Autophagy, redox signaling, and ventricular remodeling. Antioxid Redox Signal 2009; 11:1975-88. [PMID: 19327038 PMCID: PMC2848474 DOI: 10.1089/ars.2009.2524] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Revised: 02/21/2009] [Accepted: 02/25/2009] [Indexed: 12/19/2022]
Abstract
Autophagy is a catabolic process through which damaged or long-lived proteins, macromolecules, or organelles are recycled by using lysosomal degradation machinery. Although the occurrence of autophagy in several cardiac diseases including ischemic or dilated cardiomyopathy, heart failure, hypertrophy, and during ischemia/reperfusion injury have been reported, the exact role of autophagy in these diseases is not known. Emerging studies indicate that oxidative stress in cellular system could induce autophagy, and oxidatively modified macromolecules and organelles can be selectively removed by autophagy. Mild oxidative stress-induced autophagy could provide the first line of protection against major damage like apoptosis and necrosis. Cardiac-specific loss of Atg5, an autophagic gene involved in the formation of autophagosome, causes cardiac hypertrophy, left ventricular dilation, and contractile dysfunction. Recently, it was revealed that Atg4, another autophagic gene involved in the formation of autophagosomes, is controlled through redox regulation under the condition of starvation-induced autophagy. In this review, we discuss the function of autophagy in association with oxidative stress and redox signaling in the remodeling of cardiac myocardium. Further research is needed to explore the possibilities of redox regulation of other autophagic genes and the role of redox signaling-mediated autophagy in the heart.
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Affiliation(s)
- Narasimman Gurusamy
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, Connecticut 06030-1110, USA
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Gruzman A, Babai G, Sasson S. Adenosine Monophosphate-Activated Protein Kinase (AMPK) as a New Target for Antidiabetic Drugs: A Review on Metabolic, Pharmacological and Chemical Considerations. Rev Diabet Stud 2009; 6:13-36. [PMID: 19557293 DOI: 10.1900/rds.2009.6.13] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In view of the epidemic nature of type 2 diabetes and the substantial rate of failure of current oral antidiabetic drugs the quest for new therapeutics is intensive. The adenosine monophosphate-activated protein kinase (AMPK) is an important regulatory protein for cellular energy balance and is considered a master switch of glucose and lipid metabolism in various organs, especially in skeletal muscle and liver. In skeletal muscles, AMPK stimulates glucose transport and fatty acid oxidation. In the liver, it augments fatty acid oxidation and decreases glucose output, cholesterol and triglyceride synthesis. These metabolic effects induced by AMPK are associated with lowering blood glucose levels in hyperglycemic individuals. Two classes of oral antihyperglycemic drugs (biguanidines and thiazolidinediones) have been shown to exert some of their therapeutic effects by directly or indirectly activating AMPK. However, side effects and an acquired resistance to these drugs emphasize the need for the development of novel and efficacious AMPK activators. We have recently discovered a new class of hydrophobic D-xylose derivatives that activates AMPK in skeletal muscles in a non insulin-dependent manner. One of these derivatives (2,4;3,5-dibenzylidene-D-xylose-diethyl-dithioacetal) stimulates the rate of hexose transport in skeletal muscle cells by increasing the abundance of glucose transporter-4 (GLUT-4) in the plasma membrane through activation of AMPK. This compound reduces blood glucose levels in diabetic mice and therefore offers a novel strategy of therapeutic intervention strategy in type 2 diabetes. The present review describes various classes of chemically-related compounds that activate AMPK by direct or indirect interactions and discusses their potential for candidate antihyperglycemic drug development.
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Affiliation(s)
- Arie Gruzman
- Department of Pharmacology, School of Pharmacy, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
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Folmes CDL, Wagg CS, Shen M, Clanachan AS, Tian R, Lopaschuk GD. Suppression of 5'-AMP-activated protein kinase activity does not impair recovery of contractile function during reperfusion of ischemic hearts. Am J Physiol Heart Circ Physiol 2009; 297:H313-21. [PMID: 19429810 DOI: 10.1152/ajpheart.01298.2008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Activation of 5'-AMP-activated protein kinase (AMPK) may benefit the heart during ischemia-reperfusion by increasing energy production. While AMPK stimulates glycolysis, mitochondrial oxidative metabolism is the major source of ATP production during reperfusion of ischemic hearts. Stimulating AMPK increases mitochondrial fatty acid oxidation, but this is usually accompanied by a decrease in glucose oxidation, which can impair the functional recovery of ischemic hearts. To examine the relationship between AMPK and cardiac energy substrate metabolism, we subjected isolated working mouse hearts expressing a dominant negative (DN) alpha(2)-subunit of AMPK (AMPK-alpha(2) DN) to 20 min of global no-flow ischemia and 40 min of reperfusion with Krebs-Henseleit solution containing 5 mM [U-(14)C]glucose, 0.4 mM [9, 10-(3)H]palmitate, and 100 microU/ml insulin. AMPK-alpha(2) DN hearts had reduced AMPK activity at the end of reperfusion (82 +/- 9 vs. 141 +/- 7 pmol.mg(-1).min(-1)) with no changes in high-energy phosphates. Despite this, AMPK-alpha(2) DN hearts had improved recovery of function during reperfusion (14.9 +/- 0.8 vs. 9.4 +/- 1.4 beats.min(-1).mmHg.10(-3)). During reperfusion, fatty acid oxidation provided 44.0 +/- 2.8% of total acetyl-CoA in AMPK-alpha(2) DN hearts compared with 55.0 +/- 3.2% in control hearts. Since insulin can inhibit both AMPK activation and fatty acid oxidation, we also examined functional recovery in the absence of insulin. Functional recovery was similar in both groups despite a decrease in AMPK activity and a decreased reliance on fatty acid oxidation during reperfusion (66.4 +/- 9.4% vs. 85.3 +/- 4.3%). These data demonstrate that the suppression of cardiac AMPK activity does not produce an energetically compromised phenotype and does not impair, but may in fact improve, the recovery of function after ischemia.
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Affiliation(s)
- Clifford D L Folmes
- Cardiovascular Research Group and Department of Pediatrics and Pharmacology, University of Alberta, Edmonton, Alberta, Canada
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Abstract
Over the past decade, AMP-activated protein kinase (AMPK) has emerged as an important intracellular signalling pathway in the heart. Activated AMPK stimulates the production of ATP by regulating key steps in both glucose and fatty acid metabolism. It has an inhibitory effect on cardiac protein synthesis. AMPK also interacts with additional intracellular signalling pathways in a coordinated network that modulates essential cellular processes in the heart. Evidence is accumulating that AMPK may protect the heart from ischaemic injury and limit the development of cardiac myocyte hypertrophy to various stimuli. Heart AMPK is activated by hormones, cytokines and oral hypoglycaemic drugs that are used in the treatment of type 2 diabetes. The tumour suppressor LKB1 is the major regulator of AMPK activity, but additional upstream kinases and protein phosphatases also contribute. Mutations in the regulatory gamma2 subunit of AMPK lead to an inherited syndrome of hypertrophic cardiomyopathy and ventricular pre-excitation, which appears to be due to intracellular glycogen accumulation. Future research promises to elucidate the molecular mechanisms responsible for AMPK activation, novel downstream AMPK targets, and the therapeutic potential of targeting AMPK for the prevention and treatment of myocardial ischaemia or cardiac hypertrophy.
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Affiliation(s)
- A S Kim
- Departments of Internal Medicine and Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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44
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Lopaschuk GD. AMP-activated protein kinase control of energy metabolism in the ischemic heart. Int J Obes (Lond) 2009; 32 Suppl 4:S29-35. [PMID: 18719595 DOI: 10.1038/ijo.2008.120] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Myocardial ischemia produces an energy-deficient state in heart muscle, which if not corrected can lead to cardiomyocyte death. AMP-activated protein kinase (AMPK) is a key kinase that can increase energy production in the ischemic heart. During ischemia a rapid activation of AMPK occurs, resulting in an activation of both myocardial glucose uptake and glycolysis, as well as an increase in fatty acid oxidation. This activation of AMPK has the potential to increase energy production, thereby protecting the heart during ischemic stress. However, at clinically relevant high levels of fatty acids, ischemia-induced activation of AMPK also stimulates fatty acid oxidation during and following ischemia. This can contribute to ischemic injury secondary to an inhibition of glucose oxidation, which results in a decrease in cardiac efficiency. As a result, AMPK activation has the potential to be either beneficial or harmful in the ischemic heart.
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Affiliation(s)
- G D Lopaschuk
- Cardiovascular Research Group, Departments of Pediatrics and Pharmacology, Faculty of Medicine, University of Alberta, Edmonton, AB, Canada.
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Ussher JR, Lopaschuk GD. Targeting malonyl CoA inhibition of mitochondrial fatty acid uptake as an approach to treat cardiac ischemia/reperfusion. Basic Res Cardiol 2009; 104:203-10. [PMID: 19242641 DOI: 10.1007/s00395-009-0003-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 01/22/2009] [Accepted: 01/30/2009] [Indexed: 12/21/2022]
Abstract
Cardiovascular disease is the major cause of death and disability in the world, with ischemic heart disease accounting for the vast majority of this health problem. Current treatments for ischemic heart disease are primarily aimed at either increasing blood and oxygen supply to the heart or decreasing the heart's oxygen demand. A novel treatment strategy involves increasing the efficiency of oxygen use by the heart. During and following ischemia, the heart can become inefficient in using oxygen, due in part to an excessive use of fatty acids as a source of fuel. One potential strategy to increase cardiac efficiency is to inhibit this use of fatty acid oxidation as a fuel source, while stimulating the use of glucose oxidation as a fuel source, which allows the heart to produce energy more efficiently and reduces the acidosis associated with ischemia/reperfusion, both of which are beneficial to the heart. Malonyl CoA is a potent endogenous inhibitor of cardiac fatty acid oxidation, secondary to inhibition of carnitine palmitoyl transferase-I, the gatekeeper of mitochondrial fatty acid uptake. Malonyl CoA is synthesized in the heart by acetyl CoA carboxylase and degraded by malonyl CoA decarboxylase (MCD). Strategies aimed at increasing cardiac malonyl CoA levels, such as via inhibition of MCD, are associated with a decrease in fatty acid oxidation rates, and a parallel increase in glucose oxidation rates. This is associated with a decrease in acidosis and an improvement in cardiac function and efficiency during and following ischemia. Therefore, targeting malonyl CoA is a novel exciting approach for the treatment of cardiac ischemia/reperfusion.
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Affiliation(s)
- John R Ussher
- Department of Pediatrics, 423 Heritage Medical Research Center, University of Alberta, Edmonton, Canada
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46
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Scott JW, van Denderen BJW, Jorgensen SB, Honeyman JE, Steinberg GR, Oakhill JS, Iseli TJ, Koay A, Gooley PR, Stapleton D, Kemp BE. Thienopyridone drugs are selective activators of AMP-activated protein kinase beta1-containing complexes. ACTA ACUST UNITED AC 2009; 15:1220-30. [PMID: 19022182 DOI: 10.1016/j.chembiol.2008.10.005] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 09/09/2008] [Accepted: 10/02/2008] [Indexed: 11/29/2022]
Abstract
The AMP-activated protein kinase (AMPK) is an alphabetagamma heterotrimer that plays a pivotal role in regulating cellular and whole-body metabolism. Activation of AMPK reverses many of the metabolic defects associated with obesity and type 2 diabetes, and therefore AMPK is considered a promising target for drugs to treat these diseases. Recently, the thienopyridone A769662 has been reported to directly activate AMPK by an unexpected mechanism. Here we show that A769662 activates AMPK by a mechanism involving the beta subunit carbohydrate-binding module and residues from the gamma subunit but not the AMP-binding sites. Furthermore, A769662 exclusively activates AMPK heterotrimers containing the beta1 subunit. Our findings highlight the regulatory role played by the beta subunit in modulating AMPK activity and the possibility of developing isoform specific therapeutic activators of this important metabolic regulator.
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Affiliation(s)
- John W Scott
- St. Vincent's Institute and Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy 3065, VIC Australia.
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47
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Regulation of AMP-activated protein kinase by cAMP in adipocytes: roles for phosphodiesterases, protein kinase B, protein kinase A, Epac and lipolysis. Cell Signal 2009; 21:760-6. [PMID: 19167487 DOI: 10.1016/j.cellsig.2009.01.015] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 01/03/2009] [Indexed: 11/23/2022]
Abstract
AMP-activated protein kinase (AMPK) is an important regulator of cellular energy status. In adipocytes, stimuli that increase intracellular cyclic AMP (cAMP) have also been shown to increase the activity of AMPK. The precise molecular mechanisms responsible for cAMP-induced AMPK activation are not clear. Phosphodiesterase 3B (PDE3B) is a critical regulator of cAMP signaling in adipocytes. Here we investigated the roles of PDE3B, PDE4, protein kinase B (PKB) and the exchange protein activated by cAMP 1 (Epac1), as well as lipolysis, in the regulation of AMPK in primary rat adipocytes. We demonstrate that the increase in phosphorylation of AMPK at T172 induced by the adrenergic agonist isoproterenol can be diminished by co-incubation with insulin. The diminishing effect of insulin on AMPK activation was reversed upon treatment with the PDE3B specific inhibitor OPC3911 but not with the PDE4 inhibitor Rolipram. Adenovirus-mediated overexpression of PDE3B and constitutively active PKB both resulted in greatly reduced isoproterenol-induced phosphorylation of AMPK at T172. Co-incubation of adipocytes with isoproterenol and the PKA inhibitor H89 resulted in a total ablation of lipolysis and a reduction in AMPK phosphorylation/activation. Stimulation of adipocytes with the Epac1 agonist 8-pCPT-2'O-Me-cAMP led to increased phosphorylation of AMPK at T172. The general lipase inhibitor Orlistat decreased isoproterenol-induced phosphorylation of AMPK at T172. This decrease corresponded to a reduction of lipolysis from adipocytes. Taken together, these data suggest that PDE3B and PDE4 regulate cAMP pools that affect the activation/phosphorylation state of AMPK and that the effects of cyclic AMP on AMPK involve Epac1, PKA and lipolysis.
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Suchankova G, Nelson LE, Gerhart-Hines Z, Kelly M, Gauthier MS, Saha AK, Ido Y, Puigserver P, Ruderman NB. Concurrent regulation of AMP-activated protein kinase and SIRT1 in mammalian cells. Biochem Biophys Res Commun 2008; 378:836-41. [PMID: 19071085 DOI: 10.1016/j.bbrc.2008.11.130] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 11/30/2008] [Indexed: 01/11/2023]
Abstract
We examined in HepG2 cells whether glucose-induced changes in AMP-activated protein kinase (AMPK) activity could be mediated by SIRT1, an NAD(+)-dependent histone/protein deacetylase that has been linked to the increase in longevity caused by caloric restriction. Incubation with 25 vs. 5mM glucose for 6h concurrently diminished the phosphorylation of AMPK (Thr 172) and ACC (Ser 79), increased lactate release, and decreased the abundance and activity of SIRT1. In contrast, incubation with pyruvate (0.1 and 1mM) for 2h increased AMPK phosphorylation and SIRT1 abundance and activity. The putative SIRT1 activators resveratrol and quercetin also increased AMPK phosphorylation. None of the tested compounds (low or high glucose, pyruvate, and resveratrol) significantly altered the AMP/ATP ratio. Collectively, these findings raise the possibility that glucose-induced changes in AMPK are linked to alterations in SIRT1 abundance and activity and possibly cellular redox state.
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Affiliation(s)
- Gabriela Suchankova
- Department of Medicine, Section of Endocrinology, Boston Medical Center, Boston, MA 02118, USA
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Jibb LA, Richards JG. AMP-activated protein kinase activity during metabolic rate depression in the hypoxic goldfish, Carassius auratus. ACTA ACUST UNITED AC 2008; 211:3111-22. [PMID: 18805810 DOI: 10.1242/jeb.019117] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cell survival during hypoxia exposure requires a metabolic reorganization to decrease ATP demands to match the reduced capacity for ATP production. We investigated whether AMP-activated protein kinase (AMPK) activity responds to 12 h exposure to severe hypoxia ( approximately 0.3 mg O2 l(-1)) in the anoxia-tolerant goldfish (Carassius auratus). Hypoxia exposure in goldfish was characterized by a strong activation of creatine phosphate hydrolysis and glycolysis in liver and muscle. AMPK activity increased by approximately 5.5-fold in goldfish liver within 0.5 h hypoxia exposure and this increase in activity was temporally associated with an 11-fold increase in [AMP(free)]/[ATP]. No changes in total AMPK protein amount were observed, suggesting that the changes in AMPK activity are due to post-translational phosphorylation of the protein. Hypoxia exposure had no effect on the expression of two identified AMPK alpha-subunit isoforms and caused an approximately 50% decrease in the mRNA levels of AMPK beta-subunit isoform. Changes in AMPK activity in the liver were associated with an increase in percentage phosphorylation of a well-characterized target of AMPK, eukaryotic elongation factor-2 (eEF2), and decreases in protein synthesis rates measured in liver cell-free extracts. No activation of AMPK was observed in muscle, brain, heart or gill during the 12 h hypoxia exposure suggesting a tissue-specific regulation of AMPK possibly related to a lack of change in cellular [AMP(free)]/[ATP] as observed in muscle.
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Affiliation(s)
- Lindsay A Jibb
- Department of Zoology, The University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
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Abstract
Malonyl-CoA can be formed within the mitochondria, peroxisomes, and cytosol of mammalian cells. Besides being an intermediate in the pathways of de novo fatty acid biosynthesis and fatty acid elongation, malonyl-CoA has an important signaling function through its allosteric inhibition of carnitine palmitoyltransferase 1, the enzyme that normally exerts flux control over mitochondrial beta-oxidation. Malonyl-CoA is rapidly turned over in mammalian cells, and the activities of acetyl-CoA carboxylase and malonyl-CoA decarboxylase are important determinants of its cytosolic concentration. It is now recognized that malonyl-CoA participates in a diverse range of physiological or pathological responses and systems. These include the ketogenic response of the liver to fasting and diabetes, carbohydrate versus fat fuel selection in muscle tissues, metabolic changes in muscle during contracture, alterations in fatty acid metabolism during cardiac ischemia and postischemic reperfusion, stimulation of B cell insulin secretion by glucose, and the hypothalamic control of appetite.
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Affiliation(s)
- David Saggerson
- Institute of Structural & Molecular Biology, Darwin Building, University College London, Gower Street, WC1E 6BT, Great Britain.
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