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Röhling M, Herder C, Stemper T, Müssig K. Influence of Acute and Chronic Exercise on Glucose Uptake. J Diabetes Res 2016; 2016:2868652. [PMID: 27069930 PMCID: PMC4812462 DOI: 10.1155/2016/2868652] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/31/2016] [Accepted: 02/03/2016] [Indexed: 02/06/2023] Open
Abstract
Insulin resistance plays a key role in the development of type 2 diabetes. It arises from a combination of genetic predisposition and environmental and lifestyle factors including lack of physical exercise and poor nutrition habits. The increased risk of type 2 diabetes is molecularly based on defects in insulin signaling, insulin secretion, and inflammation. The present review aims to give an overview on the molecular mechanisms underlying the uptake of glucose and related signaling pathways after acute and chronic exercise. Physical exercise, as crucial part in the prevention and treatment of diabetes, has marked acute and chronic effects on glucose disposal and related inflammatory signaling pathways. Exercise can stimulate molecular signaling pathways leading to glucose transport into the cell. Furthermore, physical exercise has the potential to modulate inflammatory processes by affecting specific inflammatory signaling pathways which can interfere with signaling pathways of the glucose uptake. The intensity of physical training appears to be the primary determinant of the degree of metabolic improvement modulating the molecular signaling pathways in a dose-response pattern, whereas training modality seems to have a secondary role.
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Affiliation(s)
- Martin Röhling
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, 85764 Neuherberg, Germany
| | - Christian Herder
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, 85764 Neuherberg, Germany
| | - Theodor Stemper
- Department Fitness and Health, University Wuppertal, 42119 Wuppertal, Germany
| | - Karsten Müssig
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
- German Center for Diabetes Research (DZD), Munich, 85764 Neuherberg, Germany
- Department of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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Babar M, Farid H, Benkil B, Abdullah M, Sajid I, Nadeem A, Hussain T. Evaluation of AMPK Genes as Candidates for Production Traits in Buffalo Breeds of Pakistan. ITALIAN JOURNAL OF ANIMAL SCIENCE 2016. [DOI: 10.4081/ijas.2007.s2.345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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53
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Tang LY, Chen Y, Rui BB, Hu CM. Resveratrol ameliorates lipid accumulation in HepG2 cells, associated with down-regulation of lipin1 expression. Can J Physiol Pharmacol 2016; 94:185-189. [DOI: 10.1139/cjpp-2015-0125] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The pathogenesis of alcoholic fatty liver (AFL) disease is associated with the excessive accumulation of lipids in hepatocytes as well as oxidative stress. Resveratrol (RES), a dietary polyphenol found in red wine and grapes, has been shown to protect against AFL disease. However, the precise mechanisms that lead to this protective effect remain elusive. In this study, we used HepG2 cells to investigate the effects of RES on lipid metabolism and the mechanisms underlying these effects. HepG2 cells were cultured with oleic acid and alcohol for 48 h to induce excessive lipid accumulation. Oil red O staining showed that administration of oleic acid and alcohol induced more lipid accumulation than was observed in the control group, and that RES (15, 45, or 135 μmol/L) treatment reduced intracellular lipid droplets. RES treatment also significantly attenuated hepatic steatosis and lowered levels of intracellular triglycerides (TG). Western blot analysis showed that RES enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) and down-regulated the expression of sterol regulatory element-binding protein 1c (SREBP-1c) and lipin1. However, compound C, an AMPK inhibitor, reversed these effects of RES. In conclusion, RES reduced lipid accumulation and protected HepG2 cells. This effect may be associated with the down-regulation of SREBP-1c and lipin1 expression, increased levels of phosphorylated AMPK and ACC, and the activation of AMPK–lipin1 signaling.
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Affiliation(s)
- Li Ying Tang
- School of Pharmacy, Anhui Medical University, Anhui Key Laboratory of Bioactivity of Natural Products, 81 Meishan Road, Hefei 230032, Anhui Province, China
| | - Yi Chen
- Pharmacy department, Anhui No. 2 Province People’s Hospital, 1868 DangShan Road, Hefei, Anhui Province, China
| | - Bei Bei Rui
- Pharmacy department, Anhui No. 2 Province People’s Hospital, 1868 DangShan Road, Hefei, Anhui Province, China
| | - Cheng Mu Hu
- School of Pharmacy, Anhui Medical University, Anhui Key Laboratory of Bioactivity of Natural Products, 81 Meishan Road, Hefei 230032, Anhui Province, China
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Abstract
The metabolic syndrome (MetS) is comprised of a cluster of closely related risk factors, including visceral adiposity, insulin resistance, hypertension, high triglyceride, and low high-density lipoprotein cholesterol; all of which increase the risk for the development of type 2 diabetes and cardiovascular disease. A chronic state of inflammation appears to be a central mechanism underlying the pathophysiology of insulin resistance and MetS. In this review, we summarize recent research which has provided insight into the mechanisms by which inflammation underlies the pathophysiology of the individual components of MetS including visceral adiposity, hyperglycemia and insulin resistance, dyslipidemia, and hypertension. On the basis of these mechanisms, we summarize therapeutic modalities to target inflammation in the MetS and its individual components. Current therapeutic modalities can modulate the individual components of MetS and have a direct anti-inflammatory effect. Lifestyle modifications including exercise, weight loss, and diets high in fruits, vegetables, fiber, whole grains, and low-fat dairy and low in saturated fat and glucose are recommended as a first line therapy. The Mediterranean and dietary approaches to stop hypertension diets are especially beneficial and have been shown to prevent development of MetS. Moreover, the Mediterranean diet has been associated with reductions in total and cardiovascular mortality. Omega-3 fatty acids and peroxisome proliferator-activated receptor α agonists lower high levels of triglyceride; their role in targeting inflammation is reviewed. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone blockers comprise pharmacologic therapies for hypertension but also target other aspects of MetS including inflammation. Statin drugs target many of the underlying inflammatory pathways involved in MetS.
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Affiliation(s)
- Francine K Welty
- Division of Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass.
| | - Abdulhamied Alfaddagh
- Division of Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass
| | - Tarec K Elajami
- Division of Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass
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AMPK maintains energy homeostasis and survival in cancer cells via regulating p38/PGC-1α-mediated mitochondrial biogenesis. Cell Death Discov 2015; 1:15063. [PMID: 27551487 PMCID: PMC4979508 DOI: 10.1038/cddiscovery.2015.63] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/05/2015] [Accepted: 11/06/2015] [Indexed: 12/13/2022] Open
Abstract
Cancer cells exhibit unique metabolic response and adaptation to the fluctuating microenvironment, yet molecular and biochemical events imprinting this phenomenon are unclear. Here, we show that metabolic homeostasis and adaptation to metabolic stress in cancer cells are primarily achieved by an integrated response exerted by the activation of AMPK. We provide evidence that AMPK-p38-PGC-1α axis, by regulating energy homeostasis, maintains survival in cancer cells under glucose-limiting conditions. Functioning as a molecular switch, AMPK promotes glycolysis by activating PFK2, and facilitates mitochondrial metabolism of non-glucose carbon sources thereby maintaining cellular ATP level. Interestingly, we noted that AMPK can promote oxidative metabolism via increasing mitochondrial biogenesis and OXPHOS capacity via regulating expression of PGC-1α through p38MAPK activation. Taken together, our study signifies the fundamental role of AMPK in controlling cellular bioenergetics and mitochondrial biogenesis in cancer cells.
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56
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Sato F, Muragaki Y, Zhang Y. DEC1 negatively regulates AMPK activity via LKB1. Biochem Biophys Res Commun 2015; 467:711-6. [PMID: 26498531 DOI: 10.1016/j.bbrc.2015.10.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 10/16/2015] [Indexed: 12/16/2022]
Abstract
Basic helix-loop-helix (bHLH) transcription factor DEC1 (bHLHE40/Stra13/Sharp2) is one of the clock genes that show a circadian rhythm in various tissues. AMP-activated protein kinase (AMPK) activity plays important roles in the metabolic process and in cell death induced by glucose depletion. Recent reports have shown that AMPK activity exhibited a circadian rhythm. However, little is known regarding the regulatory mechanisms involved in the circadian rhythm of AMPK activity. The aim of this study is to investigate whether there is a direct correlation between DEC1 expression and AMPK activity. DEC1 protein and AMPK activity showed a circadian rhythm in the mouse liver with different peak levels. Knocking down DEC1 expression increased AMPK activity, whereas overexpression of DEC1 decreased it. Overexpressing the DEC1 basic mutants had little effect on the AMPK activity. DEC1 bound to the E-box of the LKB1 promoter, decreased LKB1 activity and total protein levels. There was an inverse relationship between DEC1 expression and AMPK activity. Our results suggest that DEC1 negatively regulates AMPK activity via LKB1.
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Affiliation(s)
- Fuyuki Sato
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; Department of Pathology, Wakayama Medical University School of Medicine, Wakayama 641-8509, Japan.
| | - Yasuteru Muragaki
- Department of Pathology, Wakayama Medical University School of Medicine, Wakayama 641-8509, Japan
| | - Yanping Zhang
- Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou, Jiangsu 221002, China.
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57
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Affiliation(s)
- Nathan L Price
- From the Section of Comparative Medicine, Department of Pathology, Program in Integrative Cell Signaling and Neurobiology of Metabolism and the Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT
| | - Carlos Fernández-Hernando
- From the Section of Comparative Medicine, Department of Pathology, Program in Integrative Cell Signaling and Neurobiology of Metabolism and the Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT.
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58
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Liu YJ, Chern Y. AMPK-mediated regulation of neuronal metabolism and function in brain diseases. J Neurogenet 2015; 29:50-8. [DOI: 10.3109/01677063.2015.1067203] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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59
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Pan JH, Kim JH, Kim HM, Lee ES, Shin DH, Kim S, Shin M, Kim SH, Lee JH, Kim YJ. Acetic acid enhances endurance capacity of exercise-trained mice by increasing skeletal muscle oxidative properties. Biosci Biotechnol Biochem 2015; 79:1535-41. [DOI: 10.1080/09168451.2015.1034652] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Abstract
Acetic acid has been shown to promote glycogen replenishment in skeletal muscle during exercise training. In this study, we investigated the effects of acetic acid on endurance capacity and muscle oxidative metabolism in the exercise training using in vivo mice model. In exercised mice, acetic acid induced a significant increase in endurance capacity accompanying a reduction in visceral adipose depots. Serum levels of non-esterified fatty acid and urea nitrogen were significantly lower in acetic acid-fed mice in the exercised mice. Importantly, in the mice, acetic acid significantly increased the muscle expression of key enzymes involved in fatty acid oxidation and glycolytic-to-oxidative fiber-type transformation. Taken together, these findings suggest that acetic acid improves endurance exercise capacity by promoting muscle oxidative properties, in part through the AMPK-mediated fatty acid oxidation and provide an important basis for the application of acetic acid as a major component of novel ergogenic aids.
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Affiliation(s)
- Jeong Hoon Pan
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Jun Ho Kim
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Hyung Min Kim
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Eui Seop Lee
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Dong-Hoon Shin
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Seongpil Kim
- R&D Center, Daesang Corp., Icheon, Republic of Korea
| | | | - Sang Ho Kim
- School of Global Sport Studies, Korea University, Sejong, Republic of Korea
| | - Jin Hyup Lee
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
| | - Young Jun Kim
- Department of Food and Biotechnology, Korea University, Sejong, Republic of Korea
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60
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Mul JD, Stanford KI, Hirshman MF, Goodyear LJ. Exercise and Regulation of Carbohydrate Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:17-37. [PMID: 26477909 DOI: 10.1016/bs.pmbts.2015.07.020] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Carbohydrates are the preferred substrate for contracting skeletal muscles during high-intensity exercise and are also readily utilized during moderate intensity exercise. This use of carbohydrates during physical activity likely played an important role during the survival of early Homo sapiens, and genes and traits regulating physical activity, carbohydrate metabolism, and energy storage have undoubtedly been selected throughout evolution. In contrast to the life of early H. sapiens, modern lifestyles are predominantly sedentary. As a result, intake of excessive amounts of carbohydrates due to the easy and continuous accessibility to modern high-energy food and drinks has not only become unnecessary but also led to metabolic diseases in the face of physical inactivity. A resulting metabolic disease is type 2 diabetes, a complex endocrine disorder characterized by abnormally high concentrations of circulating glucose. This disease now affects millions of people worldwide. Exercise has beneficial effects to help control impaired glucose homeostasis with metabolic disease, and is a well-established tool to prevent and combat type 2 diabetes. This chapter focuses on the effects of exercise on carbohydrate metabolism in skeletal muscle and systemic glucose homeostasis. We will also focus on the molecular mechanisms that mediate the effects of exercise to increase glucose uptake in skeletal muscle. It is now well established that there are different proximal signaling pathways that mediate the effects of exercise and insulin on glucose uptake, and these distinct mechanisms are consistent with the ability of exercise to increase glucose uptake in the face of insulin resistance in people with type 2 diabetes. Ongoing research in this area is aimed at defining the precise mechanism by which exercise increases glucose uptake and insulin sensitivity and the types of exercise necessary for these important health benefits.
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Affiliation(s)
- Joram D Mul
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Kristin I Stanford
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael F Hirshman
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Laurie J Goodyear
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA; Department of Medicine, Brigham, and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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61
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Choi YM, Kim HK, Shim W, Anwar MA, Kwon JW, Kwon HK, Kim HJ, Jeong H, Kim HM, Hwang D, Kim HS, Choi S. Mechanism of Cisplatin-Induced Cytotoxicity Is Correlated to Impaired Metabolism Due to Mitochondrial ROS Generation. PLoS One 2015; 10:e0135083. [PMID: 26247588 PMCID: PMC4527592 DOI: 10.1371/journal.pone.0135083] [Citation(s) in RCA: 175] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 07/16/2015] [Indexed: 12/18/2022] Open
Abstract
The chemotherapeutic use of cisplatin is limited by its severe side effects. In this study, by conducting different omics data analyses, we demonstrated that cisplatin induces cell death in a proximal tubular cell line by suppressing glycolysis- and tricarboxylic acid (TCA)/mitochondria-related genes. Furthermore, analysis of the urine from cisplatin-treated rats revealed the lower expression levels of enzymes involved in glycolysis, TCA cycle, and genes related to mitochondrial stability and confirmed the cisplatin-related metabolic abnormalities. Additionally, an increase in the level of p53, which directly inhibits glycolysis, has been observed. Inhibition of p53 restored glycolysis and significantly reduced the rate of cell death at 24 h and 48 h due to p53 inhibition. The foremost reason of cisplatin-related cytotoxicity has been correlated to the generation of mitochondrial reactive oxygen species (ROS) that influence multiple pathways. Abnormalities in these pathways resulted in the collapse of mitochondrial energy production, which in turn sensitized the cells to death. The quenching of ROS led to the amelioration of the affected pathways. Considering these observations, it can be concluded that there is a significant correlation between cisplatin and metabolic dysfunctions involving mROS as the major player.
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Affiliation(s)
- Yong-Min Choi
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
| | - Han-Kyul Kim
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
| | - Wooyoung Shim
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
| | - Muhammad Ayaz Anwar
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
| | - Ji-Woong Kwon
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
| | - Hyuk-Kwon Kwon
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
| | - Hyung Joong Kim
- Division of Energy Systems Research, Ajou University, Suwon, 443–749, Korea
| | - Hyobin Jeong
- School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang, 790–784, Korea
| | - Hwan Myung Kim
- Division of Energy Systems Research, Ajou University, Suwon, 443–749, Korea
| | - Daehee Hwang
- School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang, 790–784, Korea
| | - Hyung Sik Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, 440–746, Korea
| | - Sangdun Choi
- Department of Molecular Science and Technology, Ajou University, Suwon, 443–749, Korea
- * E-mail:
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Aggarwal V, Dobrolet N, Fishberger S, Zablah J, Jayakar P, Ammous Z. PRKAG2 mutation: An easily missed cardiac specific non-lysosomal glycogenosis. Ann Pediatr Cardiol 2015; 8:153-6. [PMID: 26085771 PMCID: PMC4453188 DOI: 10.4103/0974-2069.154149] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Mutations in PRKAG2 gene that regulates the γ2 subunit of the adenosine monophosphate (AMP) dependent protein kinase have been associated with the development of atrioventricular (AV) accessory pathways, cardiac hypertrophy, and conduction system abnormalities. These patients can potentially be misdiagnosed as hypertrophic cardiomyopathy (HOCM) and/or Wolf-Parkinson White (WPW) syndrome due to similar clinical phenotype. Early recognition of this disease entity is very important as ablation of suspected accessory pathways is not effective and the natural history of the disease is very different from HOCM and WPW syndrome.
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Affiliation(s)
- Varun Aggarwal
- Department of Pediatric Medical Education, Miami Children's Hospital, Miami, Florida, United States
| | - Nancy Dobrolet
- Department of Pediatric Cardiology, Miami Children's Hospital, Miami, Florida, United States
| | - Steven Fishberger
- Department of Pediatric Cardiology, Miami Children's Hospital, Miami, Florida, United States
| | - Jenny Zablah
- Department of Pediatric Medical Education, Miami Children's Hospital, Miami, Florida, United States
| | - Parul Jayakar
- Department of Medical Genetics, Miami Children's Hospital, Miami, Florida, United States
| | - Zineb Ammous
- Department of Medical Genetics, Miami Children's Hospital, Miami, Florida, United States
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63
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Cho JH, Coats SJ, Schinazi RF. Synthesis of carbocyclic nucleoside analogs with five-membered heterocyclic nucleobases. Tetrahedron Lett 2015; 56:3587-3590. [PMID: 26028788 PMCID: PMC4446795 DOI: 10.1016/j.tetlet.2015.01.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
New carbocyclic nucleoside analogs with five-membered heterocyclic nucleobases were synthesized and evaluated as potential anti-HIV and anti-HCV agents. Among the synthesized carbocyclic nucleoside analogs, the pyrazole amide 15f exhibited modest selective anti-HIV-1 activity (EC50 = 24 µM).
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Affiliation(s)
- Jong hyun Cho
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Veterans Affairs Medical Center, Atlanta, GA 30322, USA
| | | | - Raymond F. Schinazi
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, and Veterans Affairs Medical Center, Atlanta, GA 30322, USA
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Pashaj A, Xia M, Moreau R. α-Lipoic acid as a triglyceride-lowering nutraceutical. Can J Physiol Pharmacol 2015; 93:1029-41. [PMID: 26235242 DOI: 10.1139/cjpp-2014-0480] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Considering the current obesity epidemic in the United States (>100 million adults are overweight or obese), the prevalence of hypertriglyceridemia is likely to grow beyond present statistics of ∼30% of the population. Conventional therapies for managing hypertriglyceridemia include lifestyle modifications such as diet and exercise, pharmacological approaches, and nutritional supplements. It is critically important to identify new strategies that would be safe and effective in lowering hypertriglyceridemia. α-Lipoic acid (LA) is a naturally occurring enzyme cofactor found in the human body in small quantities. A growing body of evidence indicates a role of LA in ameliorating metabolic dysfunction and lipid anomalies primarily in animals. Limited human studies suggest LA is most efficacious in situations where blood triglycerides are markedly elevated. LA is commercially available as dietary supplements and is clinically shown to be safe and effective against diabetic polyneuropathies. LA is described as a potent biological antioxidant, a detoxification agent, and a diabetes medicine. Given its strong safety record, LA may be a useful nutraceutical, either alone or in combination with other lipid-lowering strategies, when treating severe hypertriglyceridemia and diabetic dyslipidemia. This review examines the current evidence regarding the use of LA as a means of normalizing blood triglycerides. Also presented are the leading mechanisms of action of LA on triglyceride metabolism.
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Affiliation(s)
- Anjeza Pashaj
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.,Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Mengna Xia
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.,Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Régis Moreau
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.,Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
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65
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Voss CM, Pajęcka K, Stridh MH, Nissen JD, Schousboe A, Waagepetersen HS. AMPK Activation Affects Glutamate Metabolism in Astrocytes. Neurochem Res 2015; 40:2431-42. [PMID: 25846006 DOI: 10.1007/s11064-015-1558-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 12/20/2022]
Abstract
Mammalian AMP-activated protein kinase (AMPK) functions as a metabolic switch. It is composed of 3 different subunits and its activation depends on phosphorylation of a threonine residue (Thr172) in the α-subunit. This phosphorylation can be brought about by 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) which in the cells is converted to a monophosphorylated nucleotide mimicking the effect of AMP. We show that the preparation of cultured astrocytes used for metabolic studies expresses AMPK, which could be phosphorylated by exposure of the cells to AICAR. The effect of AMPK activation on glutamate metabolism in astrocytes was studied using primary cultures of these cells from mouse cerebral cortex during incubation in media containing 2.5 mM glucose and 100 µM [U-(13)C]glutamate. The metabolism of glutamate including a detailed analysis of its metabolic pathways involving the tricarboxylic acid (TCA) cycle was studied using high-performance liquid chromatography analysis supplemented with gas chromatography-mass spectrometry technology. It was found that AMPK activation had profound effects on the pathways involved in glutamate metabolism since the entrance of the glutamate carbon skeleton into the TCA cycle was reduced. On the other hand, glutamate uptake into the astrocytes as well as its conversion to glutamine catalyzed by glutamine synthetase was not affected by AMPK activation. Interestingly, synthesis and release of citrate, which are hallmarks of astrocytic function, were affected by a reduction of the flux of glutamate derived carbon through the malic enzyme and pyruvate carboxylase catalyzed reactions. Finally, it was found that in the presence of glutamate as an additional substrate, glucose metabolism monitored by the use of tritiated deoxyglucose was unaffected by AMPK activation. Accordingly, the effects of AMPK activation appeared to be specific for certain key processes involved in glutamate metabolism.
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Affiliation(s)
- Caroline M Voss
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Kamilla Pajęcka
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
- Department of Clinical Medicine, The Department of Endocrinology and Diabetes, University of Aarhus, 8000, Århus, Denmark
| | - Malin H Stridh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Jakob D Nissen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
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Lee SY, Ku HC, Kuo YH, Chiu HL, Su MJ. Pyrrolidinyl caffeamide against ischemia/reperfusion injury in cardiomyocytes through AMPK/AKT pathways. J Biomed Sci 2015; 22:18. [PMID: 25879197 PMCID: PMC4367820 DOI: 10.1186/s12929-015-0125-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/05/2015] [Indexed: 12/02/2022] Open
Abstract
Background Coronary heart disease is a leading cause of death in the world and therapy to reduce injury is still needed. The uncoupling of glycolysis and glucose oxidation induces lactate accumulation during myocardial ischemia/reperfusion (I/R) injury. Cell death occurs and finally leads to myocardial infarction. Caffeic acid, one of the major phenolic constituents in nature, acts as an antioxidant. Pyrrolidinyl caffeamide (PLCA), a new derivative of caffeic acid, was synthesized by our team. We aimed to investigate the effect of PLCA on hypoxia/reoxygenation (H/R) in neonatal rat ventricular myocytes (NRVM) and on myocardial I/R in rats. Results Cardiomyocytes were isolated and subjected to 6 h hypoxia followed by 18 h reperfusion. PLCA (0.1 to 3 μM) and metformin (30 μM) were added before hypoxia was initiated. PLCA at 1 μM and metformin at 30 μM exerted similar effects on the improvement of cell viability and the alleviation of cell apoptosis in NRVM after H/R. PLCA promoted p-AMPK, p-AKT, and GLUT4 upregulation to induce a cardioprotective effect in both cell and animal model. The accumulation of cardiac lactate was attenuated by PLCA during myocardial I/R, and infarct size was smaller in rats treated with PLCA (1 mg/kg) than in those treated with caffeic acid (1 mg/kg). Conclusions AMPK and AKT are synergistically activated by PLCA, which lead facilities glucose utilization, thereby attenuating lactate accumulation and cell death. The cardioprotective dose of PLCA was lower than those of metformin and caffeic acid. We provide a new insight into this potential drug for the treatment of myocardial I/R injury.
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Affiliation(s)
- Shih-Yi Lee
- Institute of Pharmacology, College of Medicine, National Taiwan University, No.1, Sec.1, Jen-Ai Road, Taipei, 100, Taiwan. .,Division of Pulmonary and Critical Care Medicine, Mackay Memorial Hospital, Taipei, Taiwan.
| | - Hui-Chun Ku
- Institute of Pharmacology, College of Medicine, National Taiwan University, No.1, Sec.1, Jen-Ai Road, Taipei, 100, Taiwan.
| | - Yueh-Hsiung Kuo
- Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University, Taichung, Taiwan. .,Department of Biotechnology, Asia University, Taichung, Taiwan.
| | - His-Lin Chiu
- Department of Chemistry, National Taiwan University, Taipei, Taiwan.
| | - Ming-Jai Su
- Institute of Pharmacology, College of Medicine, National Taiwan University, No.1, Sec.1, Jen-Ai Road, Taipei, 100, Taiwan.
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MELK-a conserved kinase: functions, signaling, cancer, and controversy. Clin Transl Med 2015; 4:11. [PMID: 25852826 PMCID: PMC4385133 DOI: 10.1186/s40169-014-0045-y] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 12/16/2014] [Indexed: 12/15/2022] Open
Abstract
Maternal embryonic leucine zipper kinase (MELK) is a highly conserved serine/threonine kinase initially found to be expressed in a wide range of early embryonic cellular stages, and as a result has been implicated in embryogenesis and cell cycle control. Recent evidence has identified a broader spectrum of tissue expression pattern for this kinase than previously appreciated. MELK is expressed in several human cancers and stem cell populations. Unique spatial and temporal patterns of expression within these tissues suggest that MELK plays a prominent role in cell cycle control, cell proliferation, apoptosis, cell migration, cell renewal, embryogenesis, oncogenesis, and cancer treatment resistance and recurrence. These findings have important implications for our understanding of development, disease, and cancer therapeutics. Furthermore understanding MELK signaling may elucidate an added dimension of stem cell control.
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Shah SA, Yoon GH, Kim HO, Kim MO. Vitamin C Neuroprotection Against Dose-Dependent Glutamate-Induced Neurodegeneration in the Postnatal Brain. Neurochem Res 2015; 40:875-84. [DOI: 10.1007/s11064-015-1540-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 02/01/2015] [Accepted: 02/09/2015] [Indexed: 11/24/2022]
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Huang BP, Lin CH, Chen HM, Lin JT, Cheng YF, Kao SH. AMPK Activation Inhibits Expression of Proinflammatory Mediators Through Downregulation of PI3K/p38 MAPK and NF-κB Signaling in Murine Macrophages. DNA Cell Biol 2015; 34:133-41. [DOI: 10.1089/dna.2014.2630] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Bee-Piao Huang
- Department of Pathology, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan
| | - Chun-Hsiang Lin
- Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung, Taiwan
| | - Han-Min Chen
- Department of Life Science, Catholic Fu-Jen University, New Taipei City, Taiwan
- Institute of Applied Science and Engineering, Catholic Fu-Jen University, New Taipei City, Taiwan
- Energenesis Biomedical Co. Ltd., New Taipei City, Taiwan
| | - Jiun-Tsai Lin
- Energenesis Biomedical Co. Ltd., New Taipei City, Taiwan
| | - Yi-Fang Cheng
- Energenesis Biomedical Co. Ltd., New Taipei City, Taiwan
| | - Shao-Hsuan Kao
- Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung, Taiwan
- Clinical Laboratory, Chung Shan Medical University Hospital, Taichung, Taiwan
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Oh J, Lee H, Lim H, Woo S, Shin SS, Yoon M. The herbal composition GGEx18 from Laminaria japonica, Rheum palmatum, and Ephedra sinica inhibits visceral obesity and insulin resistance by upregulating visceral adipose genes involved in fatty acid oxidation. PHARMACEUTICAL BIOLOGY 2015; 53:301-12. [PMID: 25243869 DOI: 10.3109/13880209.2014.917328] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
CONTEXT The herbal composition Gyeongshingangjeehwan 18 (GGEx18) extracted from Rheum palmatum L. (Polygonaceae), Laminaria japonica Aresch (Laminariaceae), and Ephedra sinica Stapf (Ephedraceae) is traditionally used as an anti-obesity drug by local clinics in Korea. OBJECTIVE This study investigates the effects of GGEx18 on visceral obesity and insulin resistance and determines the molecular mechanisms involved in this process. MATERIALS AND METHODS After C57BL/6J mice were fed a high-fat diet supplemented with GGEx18 (125, 250, and 500 mg/kg) for 8 weeks and 3T3-L1 adipocytes were treated with GGEx18 (0.1, 1, and 10 μg/ml); variables and determinants of visceral obesity and insulin resistance were measured using in vivo and in vitro approaches. RESULTS Administration of GGEx18 to obese mice decreased visceral adipose tissue weight with an ED50 value of 232 mg/kg. 3T3-L1 adipocytes treated with GGEx18 showed a reduction in lipid accumulation with an ED50 value of 0.7 µg/ml. GGEx18 significantly increased the expression of fatty acid oxidation genes, including adiponectin, AMPKs, PPARα and its target enzymes, and CPT-1, in both mesenteric adipose tissues and 3T3-L1 cells. However, GGEx18 treatment decreased the mRNA levels of adipocyte marker genes such as PPARγ, aP2, TNFα, and leptin. GGEx18 normalized hyperglycemia and hyperinsulinemia in obese mice. Blood glucose levels of GGEx18-treated mice were significantly reduced during oral glucose tolerance tests compared with obese controls. DISCUSSION AND CONCLUSION These results suggest that GGEx18 may treat visceral obesity and visceral obesity-related insulin resistance by upregulating the visceral adipose expression of fatty acid oxidative genes.
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Affiliation(s)
- Jaeho Oh
- Department of Life Sciences, Mokwon University , Daejeon , Korea and
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Huang B, Wang Z, Park JH, Ryu OH, Choi MK, Lee JY, Kang YH, Lim SS. Anti-diabetic effect of purple corn extract on C57BL/KsJ db/db mice. Nutr Res Pract 2015; 9:22-9. [PMID: 25671064 PMCID: PMC4317475 DOI: 10.4162/nrp.2015.9.1.22] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 09/30/2014] [Accepted: 10/08/2014] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND/OBJECTIVES Recently, anthocyanins have been reported to have various biological activities. Furthermore, anthocyanin-rich purple corn extract (PCE) ameliorated insulin resistance and reduced diabetes-associated mesanginal fibrosis and inflammation, suggesting that it may have benefits for the prevention of diabetes and diabetes complications. In this study, we determined the anthocyanins and non-anthocyanin component of PCE by HPLC-ESI-MS and investigated its anti-diabetic activity and mechanisms using C57BL/KsJ db/db mice. MATERIALS/METHODS The db/db mice were divided into four groups: diabetic control group (DC), 10 or 50 mg/kg PCE (PCE 10 or PCE 50), or 10 mg/kg pinitol (pinitol 10) and treated with drugs once per day for 8 weeks. During the experiment, body weight and blood glucose levels were measured every week. At the end of treatment, we measured several diabetic parameters. RESULTS Compared to the DC group, Fasting blood glucose levels were 68% lower in PCE 50 group and 51% lower in the pinitol 10 group. Furthermore, the PCE 50 group showed 2- fold increased C-peptide and adiponectin levels and 20% decreased HbA1c levels, than in the DC group. In pancreatic islets morphology, the PCE- or pinitol-treated mice showed significant prevention of pancreatic β-cell damage and higher insulin content. Microarray analyses results indicating that gene and protein expressions associated with glycolysis and fatty acid metabolism in liver and fat tissues. In addition, purple corn extract increased the phosphorylation of AMP-activated protein kinase (AMPK) and decreased phosphoenolpyruvate carboxykinase (PEPCK), glucose 6-phosphatase (G6pase) genes in liver, and also increased glucose transporter 4 (GLUT4) expressions in skeletal muscle. CONCLUSIONS Our results suggested that PCE exerted anti-diabetic effects through protection of pancreatic β-cells, increase of insulin secretion and AMPK activation in the liver of C57BL/KsJ db/db mice.
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Affiliation(s)
- Bo Huang
- College of Food Science and Engineering, Liaoning Medical University, Jinzhou 121000, China
| | - Zhiqiang Wang
- Department of Food Science and Nutrition and Center for Aging and HealthCare, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon 200-702, Korea
| | - Jong Hyuk Park
- Institute of Natural Medicine, Hallym University Medical School, Gangwon 200-702, Korea
| | - Ok Hyun Ryu
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University, Gangwon 200-702, Korea
| | - Moon Ki Choi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University, Gangwon 200-702, Korea
| | - Jae-Yong Lee
- Institute of Natural Medicine, Hallym University Medical School, Gangwon 200-702, Korea. ; Department of Biochemistry, School of Medicine, Hallym University, Gangwon 200-702, Korea
| | - Young-Hee Kang
- Department of Food Science and Nutrition and Center for Aging and HealthCare, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon 200-702, Korea
| | - Soon Sung Lim
- Institute of Natural Medicine, Hallym University Medical School, Gangwon 200-702, Korea. ; Department of Food Science and Nutrition and Center for Aging and HealthCare, Hallym University, 1 Hallymdaehak-gil, Chuncheon, Gangwon 200-702, Korea
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Abstract
New, less toxic therapies are needed for medulloblastoma, the most common malignant brain tumor in children. Like many cancers, medulloblastomas demonstrate metabolic patterns that are markedly different from the surrounding non-neoplastic tissue and are highly organized to support tumor growth. Key aspects of medulloblastoma metabolism, including increased lipogenesis and aerobic glycolysis are derived from the metabolic programs of neural progenitors. During neural development, Sonic Hedgehog (Shh) signaling induces lipogenesis and aerobic glycolysis in proliferating progenitors to support rapid growth. Shh-regulated transcription induces specific genes, including hexokinase 2 (Hk2) and fatty acid synthase (FASN) that mediate these metabolic patterns. Medulloblastomas co-opt these developmentally-regulated patterns of metabolic gene expression for sustained tumor growth. Additionally, medulloblastomas limit protein translation through activation of eukaryotic elongation factor 2 kinase (eEF2K), to restrict energy expenditure. The activation of eEF2K reduces the need to generate ATP, enabling reduced dependence on oxidative phosphorylation and increased metabolism of glucose through aerobic glycolysis. Lipogenesis, aerobic glycolysis and restriction of protein translation operate in a network of metabolic processes that is integrated by adenosine monophosphate-activated protein kinase (AMPK) to maintain homeostasis. The homeostatic effect of AMPK has the potential to limit the impact of metabolically targeted interventions. Through combinatorial targeting of lipogenesis, glycolysis and eEF2K, however, this homeostatic effect may be overcome. We propose that combinatorial targeting of medulloblastoma metabolism may produce the synergies needed for effective anti-cancer therapy.
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Affiliation(s)
- Katherine Tech
- 1 Joint Department of Biomedical Engineering, NC State University and UNC Chapel Hill, Chapel Hill, NC 27599, USA ; 2 Department of Neurology, 3 Lineberger Comprehensive Cancer Center, 4 UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Timothy R Gershon
- 1 Joint Department of Biomedical Engineering, NC State University and UNC Chapel Hill, Chapel Hill, NC 27599, USA ; 2 Department of Neurology, 3 Lineberger Comprehensive Cancer Center, 4 UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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Gardner DK, Harvey AJ. Blastocyst metabolism. Reprod Fertil Dev 2015; 27:638-54. [DOI: 10.1071/rd14421] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/10/2015] [Indexed: 12/15/2022] Open
Abstract
The mammalian blastocyst exhibits an idiosyncratic metabolism, reflecting its unique physiology and its ability to undergo implantation. Glucose is the primary nutrient of the blastocyst, and is metabolised both oxidatively and through aerobic glycolysis. The production of significant quantities of lactate by the blastocyst reflects specific metabolic requirements and mitochondrial regulation; it is further proposed that lactate production serves to facilitate several key functions during implantation, including biosynthesis, endometrial tissue breakdown, the promotion of new blood vessel formation and induction of local immune-modulation of the uterine environment. Nutrient availability, oxygen concentration and the redox state of the blastocyst tightly regulate the relative activities of specific metabolic pathways. Notably, a loss of metabolic normality is associated with a reduction in implantation potential and subsequent fetal development. Even a transient metabolic stress at the blastocyst stage culminates in low fetal weights after transfer. Further, it is evident that there are differences between male and female embryos, with female embryos being characterised by higher glucose consumption and differences in their amino acid turnover, reflecting the presence of two active X-chromosomes before implantation, which results in differences in the proteomes between the sexes. In addition to the role of Hypoxia-Inducible Factors, the signalling pathways involved in regulating blastocyst metabolism are currently under intense analysis, with the roles of sirtuins, mTOR, AMP-activated protein kinase and specific amino acids being scrutinised. It is evident that blastocyst metabolism regulates more than the production of ATP; rather, it is apparent that metabolites and cofactors are important regulators of the epigenome, putting metabolism at centre stage when considering the interactions of the blastocyst with its environment.
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Haissaguerre M, Cota D. [Role of the mTOR pathway in the central regulation of energy balance]. Biol Aujourdhui 2015; 209:295-307. [PMID: 27021048 DOI: 10.1051/jbio/2016009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Indexed: 11/14/2022]
Abstract
The pathway of the mammalian (or mechanistic) target of rapamycin kinase (mTOR) responds to different signals such as nutrients and hormones and regulates many cellular functions as the synthesis of proteins and lipids, mitochondrial activity and the organization of the cytoskeleton. At the cellular level, mTOR forms two distinct complexes: mTORC1 and mTORC2. This review intends to summarize the various recent advances on the role of these two protein complexes in the central regulation of energy balance. mTORC1 activity modulates energy balance and metabolic responses by regulating the activity of neuronal populations, such as those located in the arcuate nucleus of the hypothalamus. Recent studies have shown that activity of the hypothalamic mTORC1 pathway varies according to cell and stimulus types, and that this signaling cascade regulates food intake and body weight in response to nutrients, such as leucine, and hormones like leptin, ghrelin and triiodothyronine. On the other hand, mTORC2 seems to be involved in the regulation of neuronal morphology and synaptic activity. However, its function in the central regulation of the energy balance is less known. Dysregulation of mTORC1 and mTORC2 is described in obesity and type 2 diabetes. Therefore, a better understanding of the molecular mechanisms involved in the regulation of energy balance by mTOR may lead to the identification of new therapeutic targets for the treatment of these metabolic pathologies.
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Affiliation(s)
- Magalie Haissaguerre
- Service Endocrinologie, Hôpital Haut Lévêque, CHU Bordeaux, 33600 Pessac, France
| | - Daniela Cota
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33000 Bordeaux, France - Université de Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33000 Bordeaux, France
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Stanford KI, Goodyear LJ. Exercise and type 2 diabetes: molecular mechanisms regulating glucose uptake in skeletal muscle. ADVANCES IN PHYSIOLOGY EDUCATION 2014; 38:308-14. [PMID: 25434013 PMCID: PMC4315445 DOI: 10.1152/advan.00080.2014] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Exercise is a well-established tool to prevent and combat type 2 diabetes. Exercise improves whole body metabolic health in people with type 2 diabetes, and adaptations to skeletal muscle are essential for this improvement. An acute bout of exercise increases skeletal muscle glucose uptake, while chronic exercise training improves mitochondrial function, increases mitochondrial biogenesis, and increases the expression of glucose transporter proteins and numerous metabolic genes. This review focuses on the molecular mechanisms that mediate the effects of exercise to increase glucose uptake in skeletal muscle.
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Affiliation(s)
- Kristin I Stanford
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Laurie J Goodyear
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
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Wi SM, Lee KY. 5-aminoimidazole-4-carboxamide Riboside Induces Apoptosis Through AMP-activated Protein Kinase-independent and NADPH Oxidase-dependent Pathways. Immune Netw 2014; 14:241-8. [PMID: 25360075 PMCID: PMC4212085 DOI: 10.4110/in.2014.14.5.241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 09/15/2014] [Accepted: 09/22/2014] [Indexed: 12/01/2022] Open
Abstract
It is debatable whether AMP-activated protein kinase (AMPK) activation is involved in anti-apoptotic or pro-apoptotic signaling. AICAR treatment increases AMPK-α1 phosphorylation, decreases intracellular reactive oxygen species (ROS) levels, and significantly increases Annexin V-positive cells, DNA laddering, and caspase activity in human myeloid cell. AMPK activation is therefore implicated in apoptosis. However, AMPK-α1-knockdown THP-1 cells are more sensitive to apoptosis than control THP-1 cells are, suggesting that the apoptosis is AMPK-independent. Low doses of AICAR induce cell proliferation, whereas high doses of AICAR suppress cell proliferation. Moreover, these effects are significantly correlated with the downregulation of intracellular ROS, strongly suggesting that AICAR-induced apoptosis is critically associated with the inhibition of NADPH oxidase by AICAR. Collectively, our results demonstrate that in AICAR-induced apoptosis, intracellular ROS levels are far more relevant than AMPK activation.
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Affiliation(s)
- Sae Mi Wi
- Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
| | - Ki-Young Lee
- Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
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Sivajothi V, Dakappa SS. In vitro and in silico antidiabetic activity of pyran ester derivative isolated from Tragia cannabina. Asian Pac J Trop Biomed 2014; 4:S455-9. [PMID: 25183128 DOI: 10.12980/apjtb.4.2014c1049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/20/2014] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVE To investigate the in vitro antidiabetic effects of isolated 4-Oxo-4H-pyran-2,6-dicarboxylic acid bis-[6-methyl-heptyl] ester from the chloroform extract of root of Tragia cannabina (T. cannabina) and AMP kinase activation property of the isolated compound. METHODS The roots of T. cannabina were collected and extracted with ethanol [95% v/v] then chromatographed over silica gel 60-120 mesh of column length 100 cm and diameter 3 cm. Elution was carried out with solvents and solvent mixtures of increasing polarities. Then the chloroform extract was used for isolation. In vitro antidiabetic activity was performed with fertile eggs of White Leghorn chicks by induction of diabetes by streptozotocin. RESULTS The isolated pyran ester binds very efficiently within the active pocket of AMPK with the formation of hydrogen bond and consuming less binding energy, which is good when compared to orientation of standard drug metformin. In in vitro antidiabetic evaluation by streptozotocin treated chick embryo the administration of isolated compound at a doses of 0.5 mg/egg and 1 mg/egg produced a significant reduction in the blood glucose levels in a dose dependant manner (P<0.01). The blood glucose level of diabetic control was (244.20±12.64) mg/dL, whereas it was (207.40±2.43) mg/dL (P<0.001) for isolated compound 0.5 mg/egg and 174.800±2.410 mg/dL (P<0.001) for 1 mg/ egg of the isolated compound. CONCLUSIONS The significant glucose levels were reduced (P<0.01) after administration of the pyran ester isolated from T. cannabina to streptozotocin treated chick embryo.
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Affiliation(s)
- Vaiyapuri Sivajothi
- Department of Pharmaceutical Chemistry, The Oxford College of Pharmacy, Bangalore -68, Karnataka, India
| | - Shruthi Shirur Dakappa
- Microbiology and Cell Biology Department, Indian Institute of Science, Bangalore-560012, Karnataka, India
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Swamy M, Suhaili D, Sirajudeen KNS, Mustapha Z, Govindasamy C. Propolis ameliorates tumor nerosis factor-α, nitric oxide levels, caspase-3 and nitric oxide synthase activities in kainic acid mediated excitotoxicity in rat brain. AFRICAN JOURNAL OF TRADITIONAL, COMPLEMENTARY, AND ALTERNATIVE MEDICINES 2014; 11:48-53. [PMID: 25395704 DOI: 10.4314/ajtcam.v11i5.8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND Increased nitric oxide (NO), neuronal inflammation and apoptosis have been proposed to be involved in excitotoxicity plays a part in many neurodegenerative diseases. To understand the neuro-protective effects of propolis, activities of Nitric oxide synthase (NOS) and caspase-3 along with NO and tumor necrosis factor-α (TNF-α) levels were studied in cerebral cortex (CC), cerebellum (CB) and brain stem (BS) in rats supplemented with propolis prior to excitotoxic injury with kainic acid (KA). MATERIALS AND METHODS Male Sprague-Dawley rats were divided into four groups (n=6 rats per group) as Control, KA, Propolis and KA+Propolis. The control group and KA group have received vehicle and saline. Propolis group and propolis + KA group were orally administered with propolis (150 mg/kg body weight), five times every 12 hours. KA group and propolis +KA group were injected subcutaneously with kainic acid (15 mg/kg body weight) and were sacrificed after 2 hrs. CC, CB and BS were separated, homogenized and used for estimation of NOS, caspase-3, NO and TNF-α by commercial kits. Results were analyzed by one way ANOVA, reported as mean + SD (n=6 rats), and p<0.05 was considered statistically significant. RESULTS The concentration of NO, TNF-α, NOS and caspase-3 activity were increased significantly (p<0.001) in all the three brain regions tested in KA group compared to the control. Propolis supplementation significantly (p<0.001) prevented the increase in NOS, NO, TNF-α and caspase-3 due to KA. CONCLUSION Results of this study clearly demonstrated that the propolis supplementation attenuated the NOS, caspase-3 activities, NO, and TNF-α concentration and in KA mediated excitotoxicity. Hence propolis can be a possible potential protective agent against excitotoxicity and neurodegenerative disorders.
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Affiliation(s)
- Mummedy Swamy
- Department of Chemical Pathology, School of Medical Sciences, Health campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - Dian Suhaili
- Department of Chemical Pathology, School of Medical Sciences, Health campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - K N S Sirajudeen
- Department of Chemical Pathology, School of Medical Sciences, Health campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - Zulkarnain Mustapha
- Department of Chemical Pathology, School of Medical Sciences, Health campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - Chandran Govindasamy
- Department of Chemical Pathology, School of Medical Sciences, Health campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
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Duan W, Jiang M, Jin J. Metabolism in HD: still a relevant mechanism? Mov Disord 2014; 29:1366-74. [PMID: 25124273 DOI: 10.1002/mds.25992] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 07/22/2014] [Indexed: 12/14/2022] Open
Abstract
The polyglutamine expansion within huntingtin is the causative factor in the pathogenesis of Huntington's disease (HD). Although the underlying mechanisms by which mutant huntingtin causes neuronal dysfunction and degeneration have not been fully elucidated, compelling evidence suggests that mitochondrial dysfunction and compromised energy metabolism are key players in HD pathogenesis. Longitudinal studies of HD subjects have shown reductions in glucose utilization before the disease clinical onset. Preferential striatal neurodegeneration, a hallmark of HD pathogenesis, also has been associated with interrupted energy metabolism. Data from genetic HD models indicate that mutant huntingtin disrupts mitochondrial bioenergetics and prevents adenosine triphosphate (ATP) generation, implying altered energy metabolism as an important component of HD pathogenesis. Here we revisit the evidence of abnormal energy metabolism in the central nervous system of HD patients, review our current understanding of the molecular mechanisms underlying abnormal metabolism induced by mutant huntingtin, and discuss the promising therapeutic development by halting abnormal metabolism in HD.
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Affiliation(s)
- Wenzhen Duan
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Tsunoda K, Kai Y, Uchida K, Kuchiki T, Nagamatsu T. Physical activity and risk of fatty liver in people with different levels of alcohol consumption: a prospective cohort study. BMJ Open 2014; 4:e005824. [PMID: 25095878 PMCID: PMC4127917 DOI: 10.1136/bmjopen-2014-005824] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/08/2014] [Accepted: 07/10/2014] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To investigate whether physical activity affects the future incidence of fatty liver in people with never-moderate and heavy alcohol consumption. DESIGN Prospective cohort study. SETTING Health check-up programme at Meiji Yasuda Shinjuku Medical Center in Shinjuku Ward, Tokyo, Japan. POPULATION A total of 10,146 people aged 18 years or older without fatty liver enrolled through baseline surveys conducted from 2005 to 2007. They were grouped into never-moderate alcohol drinkers (n=7803) and heavy alcohol drinkers (n=2343) and followed until 2013. MAIN OUTCOME MEASURE Incident fatty liver diagnosed by ultrasound. RESULTS During a mean follow-up of 4.4 years (34,648 person-years), 1255 never-moderate alcohol drinkers developed fatty liver; 520 heavy alcohol drinkers developed fatty liver during a mean follow-up of 4.1 years (9596 person-years). For never-moderate alcohol drinkers, engaging in >3×/week of low-intensity (HR=0.82, 95% CI 0.71 to 0.96) and moderate-intensity (HR=0.56, 95% CI 0.39 to 0.81) physical activity significantly reduced incident fatty liver compared with those who engaged in physical activity <1×/week. For vigorous-intensity physical activity, frequencies of 2×/week (HR=0.57, 95% CI 0.38 to 0.86) and >3×/week (HR=0.55, 95% CI 0.38 to 0.79) were significantly associated with lower risk of incident fatty liver. In propensity-adjusted models, these significant associations still remained. By contrast, in heavy alcohol drinkers, there were no significant associations between the type or frequency of physical activity and incident fatty liver. CONCLUSIONS Physical activity had an independent protective effect on incident fatty liver only in the never-moderate alcohol drinkers, and the preventive effect increased with higher frequencies and intensities of physical activity.
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Affiliation(s)
- Kenji Tsunoda
- Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Hachioji, Tokyo, Japan
| | - Yuko Kai
- Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Hachioji, Tokyo, Japan
| | - Ken Uchida
- Meiji Yasuda Shinjuku Medical Center, Meiji Yasuda Life Foundation of Health and Welfare, Shinjuku, Tokyo, Japan
| | - Tsutomu Kuchiki
- Meiji Yasuda Wellness Development Office, Meiji Yasuda Life Foundation of Health and Welfare, Shinjuku, Tokyo, Japan
| | - Toshiya Nagamatsu
- Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Hachioji, Tokyo, Japan
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81
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Ramratnam M, Sharma RK, D'Auria S, Lee SJ, Wang D, Huang XYN, Ahmad F. Transgenic knockdown of cardiac sodium/glucose cotransporter 1 (SGLT1) attenuates PRKAG2 cardiomyopathy, whereas transgenic overexpression of cardiac SGLT1 causes pathologic hypertrophy and dysfunction in mice. J Am Heart Assoc 2014; 3:jah3629. [PMID: 25092788 PMCID: PMC4310371 DOI: 10.1161/jaha.114.000899] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background The expression of a novel cardiac glucose transporter, SGLT1, is increased in glycogen storage cardiomyopathy secondary to mutations in PRKAG2. We sought to determine the role of SGLT1 in the pathogenesis of PRKAG2 cardiomyopathy and its role in cardiac structure and function. Methods and Results Transgenic mice with cardiomyocyte‐specific overexpression of human T400N mutant PRKAG2 cDNA (TGT400N) and transgenic mice with cardiomyocyte‐specific RNA interference knockdown of SGLT1 (TGSGLT1‐DOWN) were crossed to produce double‐transgenic mice (TGT400N/TGSGLT1‐DOWN). Tet‐off transgenic mice conditionally overexpressing cardiac SGLT1 in the absence of doxycycline were also constructed (TGSGLT‐ON). Relative to TGT400N mice, TGT400N/TGSGLT1‐DOWN mice exhibited decreases in cardiac SGLT1 expression (63% decrease, P<0.05), heart/body weight ratio, markers of cardiac hypertrophy, and cardiac glycogen content. TGT400N/TGSGLT1‐DOWN mice had less left ventricular dilation at age 12 weeks compared to TGT400N mice. Relative to wildtype (WT) mice, TGSGLT1‐ON mice exhibited increases in heart/body weight ratio, glycogen content, and markers of cardiac hypertrophy at ages 10 and 20 weeks. TGSGLT1‐ON mice had increased myocyte size and interstitial fibrosis, and progressive left ventricular dysfunction. When SGLT1 was suppressed after 10 weeks of overexpression (TGSGLT1‐ON/OFF), there was a reduction in cardiac hypertrophy and improvement in left ventricular failure. Conclusions Cardiac knockdown of SGLT1 in a murine model of PRKAG2 cardiomyopathy attenuates the disease phenotype, implicating SGLT1 in the pathogenesis. Overexpression of SGLT1 causes pathologic cardiac hypertrophy and left ventricular failure that is reversible. This is the first report of cardiomyocyte‐specific transgenic knockdown of a target gene.
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Affiliation(s)
- Mohun Ramratnam
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI (M.R.) UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.)
| | - Ravi K Sharma
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.)
| | - Stephen D'Auria
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.)
| | - So Jung Lee
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.)
| | - David Wang
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.)
| | - Xue Yin N Huang
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.)
| | - Ferhaan Ahmad
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA (M.R., R.K.S., S.A., S.J.L., D.W., X.Y.N.H., F.A.) Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA (F.A.) Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA (F.A.)
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82
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Zhu CT, Ingelmo P, Rand DM. G×G×E for lifespan in Drosophila: mitochondrial, nuclear, and dietary interactions that modify longevity. PLoS Genet 2014; 10:e1004354. [PMID: 24832080 PMCID: PMC4022469 DOI: 10.1371/journal.pgen.1004354] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 03/23/2014] [Indexed: 01/05/2023] Open
Abstract
Dietary restriction (DR) is the most consistent means of extending longevity in a wide range of organisms. A growing body of literature indicates that mitochondria play an important role in longevity extension by DR, but the impact of mitochondrial genotypes on the DR process have received little attention. Mitochondrial function requires proper integration of gene products from their own genomes (mtDNA) and the nuclear genome as well as the metabolic state of the cell, which is heavily influenced by diet. These three-way mitochondrial-nuclear-dietary interactions influence cellular and organismal functions that affect fitness, aging, and disease in nature. To examine these interactions in the context of longevity, we generated 18 "mito-nuclear" genotypes by placing mtDNA from strains of Drosophila melanogaster and D. simulans onto controlled nuclear backgrounds of D. melanogaster (Oregon-R, w1118, SIR2 overexpression and control) and quantified the lifespan of each mitonuclear genotype on five different sugar:yeast diets spanning a range of caloric and dietary restriction (CR and DR). Using mixed effect models to quantify main and interaction effects, we uncovered strong mitochondrial-diet, mitochondrial-nuclear, and nuclear-diet interaction effects, in addition to three-way interactions. Survival analyses demonstrate that interaction effects can be more important than individual genetic or dietary effects on longevity. Overexpression of SIR2 reduces lifespan variation among different mitochondrial genotypes and further dampens the response of lifespan to CR but not to DR, suggesting that response to these two diets involve different underlying mechanisms. Overall the results reveal that mitochondrial-nuclear genetic interactions play important roles in modulating Drosophila lifespan and these epistatic interactions are further modified by diet. More generally, these findings illustrate that gene-by-gene and gene-by-environment interactions are not simply modifiers of key factors affecting longevity, but these interactions themselves are the very factors that underlie important variation in this trait.
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Affiliation(s)
- Chen-Tseh Zhu
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (CTZ); (DMR)
| | - Paul Ingelmo
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America
| | - David M. Rand
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (CTZ); (DMR)
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83
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Cook M, Bolkan BJ, Kretzschmar D. Increased actin polymerization and stabilization interferes with neuronal function and survival in the AMPKγ mutant Loechrig. PLoS One 2014; 9:e89847. [PMID: 24587072 PMCID: PMC3934941 DOI: 10.1371/journal.pone.0089847] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 01/27/2014] [Indexed: 11/18/2022] Open
Abstract
loechrig (loe) mutant flies are characterized by progressive neuronal degeneration, behavioral deficits, and early death. The mutation is due to a P-element insertion in the gene for the γ-subunit of the trimeric AMP-activated protein kinase (AMPK) complex, whereby the insertion affects only one of several alternative transcripts encoding a unique neuronal isoform. AMPK is a cellular energy sensor that regulates a plethora of signaling pathways, including cholesterol and isoprenoid synthesis via its downstream target hydroxy-methylglutaryl (HMG)-CoA reductase. We recently showed that loe interferes with isoprenoid synthesis and increases the prenylation and thereby activation of RhoA. During development, RhoA plays an important role in neuronal outgrowth by activating a signaling cascade that regulates actin dynamics. Here we show that the effect of loe/AMPKγ on RhoA prenylation leads to a hyperactivation of this signaling pathway, causing increased phosphorylation of the actin depolymerizating factor cofilin and accumulation of filamentous actin. Furthermore, our results show that the resulting cytoskeletal changes in loe interfere with neuronal growth and disrupt axonal integrity. Surprisingly, these phenotypes were enhanced by expressing the Slingshot (SSH) phosphatase, which during development promotes actin depolymerization by dephosphorylating cofilin. However, our studies suggest that in the adult SSH promotes actin polymerization, supporting in vitro studies using human SSH1 that suggested that SSH can also stabilize and bundle filamentous actin. Together with the observed increase in SSH levels in the loe mutant, our experiments suggest that in mature neurons SSH may function as a stabilization factor for filamentous actin instead of promoting actin depolymerization.
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Affiliation(s)
- Mandy Cook
- Oregon Institute of Occupational Health Sciences, Oregon Health & Sciences University, Portland, Oregon, United States of America
| | - Bonnie J. Bolkan
- Oregon Institute of Occupational Health Sciences, Oregon Health & Sciences University, Portland, Oregon, United States of America
| | - Doris Kretzschmar
- Oregon Institute of Occupational Health Sciences, Oregon Health & Sciences University, Portland, Oregon, United States of America
- * E-mail:
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84
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Jung CH, Lee MJ, Kang YM, Lee YL, Yoon HK, Kang SW, Lee WJ, Park JY. Vaspin inhibits cytokine-induced nuclear factor-kappa B activation and adhesion molecule expression via AMP-activated protein kinase activation in vascular endothelial cells. Cardiovasc Diabetol 2014; 13:41. [PMID: 24517399 PMCID: PMC3925442 DOI: 10.1186/1475-2840-13-41] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 02/11/2014] [Indexed: 12/17/2022] Open
Abstract
Background Vaspin is an adipocytokine that was recently identified in the visceral adipose tissue of diabetic rats and has anti-diabetic and anti-atherogenic effects. We hypothesized that vaspin prevents inflammatory cytokine-induced nuclear factor-kappa B (NF-κB) activation by activating AMP-activated protein kinase (AMPK) in vascular endothelial cells. Methods We examined the effects of vaspin on NF-κB activation and the expression of the NF-κB-mediated genes intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and monocyte chemoattractant protein-1 (MCP-1). Human aortic endothelial cells (HAECS) were used. Tumor necrosis factor alpha (TNFα) was used as a representative proinflammatory cytokine. Results Treatment with vaspin significantly increased the phosphorylation of AMPK and acetyl-CoA carboxylase, the down-stream target of AMPK. Furthermore, treatment with vaspin significantly decreased TNFα-induced activation of NF-κB, as well as the expression of the adhesion molecules ICAM-1, VCAM-1, E-selectin, and MCP-1. These effects were abolished following transfection of AMPKα1-specific small interfering RNA. In an adhesion assay using THP-1 cells, vaspin reduced TNFα-induced adhesion of monocytes to HAECS in an AMPK-dependent manner. Conclusions Vaspin might attenuate the cytokine-induced expression of adhesion molecule genes by inhibiting NF-κB following AMPK activation.
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Affiliation(s)
| | | | | | | | | | | | | | - Joong-Yeol Park
- Department of Internal Medicine, University of Ulsan College of Medicine, Poongnap-dong, Songpa-gu, Seoul 138-736, Korea.
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85
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Ullah I, Park HY, Kim MO. Anthocyanins protect against kainic acid-induced excitotoxicity and apoptosis via ROS-activated AMPK pathway in hippocampal neurons. CNS Neurosci Ther 2014; 20:327-38. [PMID: 24393263 DOI: 10.1111/cns.12218] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/20/2013] [Accepted: 11/24/2013] [Indexed: 12/15/2022] Open
Abstract
INTRODUCTION Excitotoxicity is an important mechanism involved in neurodegeneration. Kainic acid (KA)-induced excitotoxicity results an unfavorable stress, and we investigated the signaling pathways activated in such conditions. AIMS Here, we sought to determine the cellular and biochemical benefits of anthocyanins extracted from Korean black bean against KA-induced excitotoxicity and neuronal cell death. METHODS AND RESULTS Mouse hippocampal cell line (HT22) and primary prenatal rat hippocampal neurons were treated with KA to induce excitotoxicity. Incubation of the cells with KA alone significantly decreased cell viability, elevated intracellular Ca(2+) level, increased generation of reactive oxygen species (ROS) and loss of mitochondrial membrane potential (Δψ(M)). These events were accompanied by sustained phosphorylation and activation of AMP-activated protein kinase (AMPK). Kainic acid induced upregulation of Bax, decrease in Bcl-2, release of cytochrome-c, and activation of caspase-3 in both cell types. Anthocyanins attenuated KA-induced dysregulation of Ca(2+), ROS accumulation, activation of AMPK, and increase in percentage of apoptotic cells. Pretreatment of the cells with compound C, an inhibitor of AMPK, diminished the KA-induced activation of AMPK and caspase-3. The activation of AMPK through elevation of cellular ROS and Ca(2+) levels is required for KA-induced apoptosis in hippocampal neurons. CONCLUSIONS In summary, our data suggest that although anthocyanins have diverse activities, at least part of their beneficial effects against KA-induced hippocampal degeneration can be attributed to their well-recognized antioxidant properties.
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Affiliation(s)
- Ikram Ullah
- Department of Biology, College of Natural Sciences (RINS), Applied Life Science (BK 21) Gyeongsang National University, Jinju, Korea
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86
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Kostovski E, Boon H, Hjeltnes N, Lundell LS, Ahlsén M, Chibalin AV, Krook A, Iversen PO, Widegren U. Altered content of AMP-activated protein kinase isoforms in skeletal muscle from spinal cord injured subjects. Am J Physiol Endocrinol Metab 2013; 305:E1071-80. [PMID: 24022865 DOI: 10.1152/ajpendo.00132.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
AMP-activated protein kinase (AMPK) is a pivotal regulator of energy homeostasis. Although downstream targets of AMPK are widely characterized, the physiological factors governing isoform expression of this protein kinase are largely unknown. Nerve/contractile activity has a major impact on the metabolic phenotype of skeletal muscle, therefore likely to influence AMPK isoform expression. Spinal cord injury represents an extreme form of physical inactivity, with concomitant changes in skeletal muscle metabolism. We assessed the influence of longstanding and recent spinal cord injury on protein abundance of AMPK isoforms in human skeletal muscle. We also determined muscle fiber type as a marker of glycolytic or oxidative metabolism. In subjects with longstanding complete injury, protein abundance of the AMPKγ3 subunit, as well as myosin heavy chain (MHC) IIa and IIx, were increased, whereas abundance of the AMPKγ1 subunit and MHC I were decreased. Similarly, abundance of AMPKγ3 and MHC IIa proteins were increased, whereas AMPKα2, -β1, and -γ1 subunits and MHC I abundance was decreased during the first year following injury, reflecting a more glycolytic phenotype of the skeletal muscle. However, in incomplete cervical lesions, partial recovery of muscle function attenuated the changes in the isoform profile of AMPK and MHC. Furthermore, exercise training (electrically stimulated leg cycling) partly normalized mRNA expression of AMPK isoforms. Thus, physical activity affects the relative expression of AMPK isoforms. In conclusion, skeletal muscle abundance of AMPK isoforms is related to physical activity and/or muscle fiber type. Thus, physical/neuromuscular activity is an important determinant of isoform abundance of AMPK and MCH. This further underscores the need for physical activity as part of a treatment regimen after spinal cord injury to maintain skeletal muscle metabolism.
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Affiliation(s)
- Emil Kostovski
- Section for Spinal Cord Injury, Sunnaas Rehabilitation Hospital, Nesoddtangen, Norway
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87
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Avery LB, Bumpus NN. Valproic acid is a novel activator of AMP-activated protein kinase and decreases liver mass, hepatic fat accumulation, and serum glucose in obese mice. Mol Pharmacol 2013; 85:1-10. [PMID: 24105977 DOI: 10.1124/mol.113.089755] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Valproic acid (VPA) is a widely prescribed anticonvulsant for the treatment of epilepsy. Here we demonstrate that VPA is a novel activator of AMP-activated protein kinase (AMPK), a key regulator of cellular metabolism, using primary mouse and human hepatocytes. Incubation of primary mouse hepatocytes with VPA resulted in increased levels of phosphorylated AMPK and acetyl-CoA carboxylase (ACC). This finding was recapitulated using primary human hepatocytes. Pretreatment of mouse hepatocytes with a small-molecule inhibitor of AMPK, Compound C (6-[4-(2-piperidin-1-ylethoxy)phenyl]-3-pyridin-4-ylpyrazolo[1,5-a]pyrimidine), abrogated the phosphorylation of ACC following treatment with VPA. The cytochrome P450 inhibitor 1-aminobenzotriazole blocked the VPA-stimulated phosphorylation of AMPK, suggesting a requirement for biotransformation of VPA. In line with this, treatment of hepatocytes with metabolites of VPA resulted in increased phosphorylation of AMPK/ACC as compared with VPA. Treatment of ob/ob mice with VPA for 14 days resulted in decreased liver masses, hepatic fat accumulation, and serum glucose. These results paralleled those observed in mice treated with metformin. In addition, a targeted mass spectrometry-based metabolomics assay revealed several small molecules that were differentially abundant in the serum of ob/ob mice treated with VPA as compared with vehicle-treated mice. These studies are the first to establish VPA and its metabolites as in vitro activators of AMPK.
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Affiliation(s)
- Lindsay B Avery
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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88
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Wu WN, Wu PF, Zhou J, Guan XL, Zhang Z, Yang YJ, Long LH, Xie N, Chen JG, Wang F. Orexin-A Activates Hypothalamic AMP-Activated Protein Kinase Signaling through a Ca2+-Dependent Mechanism Involving Voltage-Gated L-Type Calcium Channel. Mol Pharmacol 2013; 84:876-87. [DOI: 10.1124/mol.113.086744] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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Cao S, Zhou Y, Xu P, Wang Y, Yan J, Bin W, Qiu F, Kang N. Berberine metabolites exhibit triglyceride-lowering effects via activation of AMP-activated protein kinase in Hep G2 cells. JOURNAL OF ETHNOPHARMACOLOGY 2013; 149:576-582. [PMID: 23899453 DOI: 10.1016/j.jep.2013.07.025] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 06/22/2013] [Accepted: 07/23/2013] [Indexed: 06/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Rhizoma coptidis (Huanglian in Chinese) is commonly used in Chinese folk medicine to treat diarrhea, diabetes, hypertension, hyperlipidemia and tumors. This herb has increasingly gained attention because of its use as a hypolipidemic herb. Berberine (BBR) is the most important constituent of R. coptidis that contribute to the pharmacological efficacy of the herb. AIM OF THE STUDY Pharmacokinetic studies have indicated that BBR has poor oral bioavailability. Interestingly, several reports show that absorbed BBR is extensively metabolized in rats and humans. We speculate that the BBR metabolites might be responsible for the pharmacological effects. The aim of this study is to examine BBR metabolites for their triglyceride (TG)-lowering activities and the molecular mechanism to clarify BBR genuine effective forms in vivo. MATERIALS AND METHODS Four BBR metabolites were examined their TG-lowering effects with a commercial triglyceride assay kit. Real-time PCR and Western blotting were used to confirm genes and proteins of interest, respectively. RESULTS Among those BBR metabolites, M2 exhibited the more potential effects on TG-lowering and AMP-activated protein kinase (AMPK) activation in Hep G2 cells as compared with BBR. Moreover, BBR and M2 inhibited gene expressions of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), glycerol-3-phosphate acyltransferase (GPAT) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), but motivated gene expression of medium chain acyl-CoA dehydrogenase (mCAD) significantly. CONCLUSIONS The results suggested that the TG-lowering effects of BBR and M2 might be partially mediated by the up-regulation of lipolysis gene expressions and down-regulation of lipogenesis gene expressions through activation of the AMPK signaling pathway. BBR and its metabolites might be in vivo active forms of oral doses of BBR, and M2 might be a promising drug candidate against hyperlipidemia.
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Affiliation(s)
- Shijie Cao
- Department of Biochemistry and Molecular Biology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
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90
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Cheong SH, Furuhashi K, Ito K, Nagaoka M, Yonezawa T, Miura Y, Yagasaki K. Antihyperglycemic effect of equol, a daidzein derivative, in cultured L6 myocytes andob/obmice. Mol Nutr Food Res 2013; 58:267-77. [DOI: 10.1002/mnfr.201300272] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/17/2013] [Accepted: 07/04/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Sun Hee Cheong
- Department of Applied Biological Chemistry; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
- Department of Biotechnology; Konkuk University; Chungju Republic of Korea
| | - Keisuke Furuhashi
- Department of Applied Biological Chemistry; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Katsuki Ito
- Department of Applied Biological Chemistry; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Masato Nagaoka
- Department of Applied Biological Chemistry; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Takayuki Yonezawa
- Graduate School of Medicine; The University of Tokyo; Bunkyo-Ku Tokyo Japan
| | - Yutaka Miura
- Department of Applied Biological Chemistry; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
| | - Kazumi Yagasaki
- Department of Applied Biological Chemistry; Tokyo University of Agriculture and Technology; Fuchu Tokyo Japan
- Graduate School of Medicine; The University of Tokyo; Bunkyo-Ku Tokyo Japan
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Martin-Hidalgo D, Hurtado de Llera A, Yeste M, Gil MC, Bragado MJ, Garcia-Marin LJ. Adenosine monophosphate-activated kinase, AMPK, is involved in the maintenance of the quality of extended boar semen during long-term storage. Theriogenology 2013; 80:285-94. [DOI: 10.1016/j.theriogenology.2013.02.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 01/30/2013] [Accepted: 02/19/2013] [Indexed: 12/29/2022]
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92
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Pung YF, Sam WJ, Hardwick JP, Yin L, Ohanyan V, Logan S, Di Vincenzo L, Chilian WM. The role of mitochondrial bioenergetics and reactive oxygen species in coronary collateral growth. Am J Physiol Heart Circ Physiol 2013; 305:H1275-80. [PMID: 23997092 DOI: 10.1152/ajpheart.00077.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Coronary collateral growth is a process involving coordination between growth factors expressed in response to ischemia and mechanical forces. Underlying this response is proliferation of vascular smooth muscle and endothelial cells, resulting in an enlargement in the caliber of arterial-arterial anastomoses, i.e., a collateral vessel, sometimes as much as an order of magnitude. An integral element of this cell proliferation is the process known as phenotypic switching in which cells of a particular phenotype, e.g., contractile vascular smooth muscle, must change their phenotype to proliferate. Phenotypic switching requires that protein synthesis occurs and different kinase signaling pathways become activated, necessitating energy to make the switch. Moreover, kinases, using ATP to phosphorylate their targets, have an energy requirement themselves. Mitochondria play a key role in the energy production that enables phenotypic switching, but under conditions where mitochondrial energy production is constrained, e.g., mitochondrial oxidative stress, this switch is impaired. In addition, we discuss the potential importance of uncoupling proteins as modulators of mitochondrial reactive oxygen species production and bioenergetics, as well as the role of AMP kinase as an energy sensor upstream of mammalian target of rapamycin, the master regulator of protein synthesis.
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Affiliation(s)
- Yuh Fen Pung
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio
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Bmf upregulation through the AMP-activated protein kinase pathway may protect the brain from seizure-induced cell death. Cell Death Dis 2013; 4:e606. [PMID: 23618904 PMCID: PMC3668628 DOI: 10.1038/cddis.2013.136] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Prolonged seizures (status epilepticus, SE) can cause neuronal death within brain regions such as the hippocampus. This may contribute to impairments in cognitive functioning and trigger or exacerbate epilepsy. Seizure-induced neuronal death is mediated, at least in part, by apoptosis-associated signaling pathways. Indeed, mice lacking certain members of the potently proapoptotic BH3-only subfamily of Bcl-2 proteins are protected against hippocampal damage caused by status epilepticus. The recently identified BH3-only protein Bcl-2-modifying factor (Bmf) normally interacts with the cytoskeleton, but upon certain cellular stresses, such as loss of extracellular matrix adhesion or energy crisis, Bmf relocalizes to mitochondria, where it can promote Bax activation and mitochondrial dysfunction. Although Bmf has been widely reported in the hematopoietic system to exert a proapoptotic effect, no studies have been undertaken in models of neurological disorders. To examine whether Bmf is important for seizure-induced neuronal death, we studied Bmf induction after prolonged seizures induced by intra-amygdala kainic acid (KA) in mice, and examined the effect of Bmf-deficiency on seizures and damage caused by SE. Seizures triggered an early (1-8 h) transcriptional activation and accumulation of Bax in the cell death-susceptible hippocampal CA3 subfield. Bmf mRNA was biphasically upregulated beginning at 1 h after SE and returning to normal by 8 h, while again being found elevated in the hippocampus of epileptic mice. Bmf upregulation was prevented by Compound C, an inhibitor of adenosine monophosphate-activated protein kinase, indicating Bmf expression may be induced in response to bioenergetic stress. Bmf-deficient mice showed normal sensitivity to the convulsant effects of KA, but, surprisingly, displayed significantly more neuronal death in the hippocampal CA1 and CA3 subfields after SE. These are the first studies investigating Bmf in a model of neurologic injury, and suggest that Bmf may protect neurons against seizure-induced neuronal death in vivo.
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94
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Balasubramanian R, Maruoka H, Jayasekara PS, Gao ZG, Jacobson KA. AMP-activated protein kinase as regulator of P2Y(6) receptor-induced insulin secretion in mouse pancreatic β-cells. Biochem Pharmacol 2013; 85:991-8. [PMID: 23333427 PMCID: PMC3594329 DOI: 10.1016/j.bcp.2012.11.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 11/23/2012] [Accepted: 11/26/2012] [Indexed: 10/27/2022]
Abstract
5'-AMP-activated protein kinase (AMPK) and its pharmacological modulators have been targeted for treating type 2 diabetes. Extracellular uridine 5'-diphosphate (UDP) activates P2Y6 receptors (P2Y6Rs) in pancreatic β-cells to release insulin and reduce apoptosis, which would benefit diabetes. Here, we studied the role of P2Y6R in activation of AMPK in MIN6 mouse pancreatic β-cells and insulin secretion. Treatment with a potent P2Y6R dinucleotide agonist MRS2957 (500nM) activated AMPK, which was blocked by P2Y6R-selective antagonist MRS2578. Also, MRS2957 induced phosphorylation of acetyl-coenzyme A carboxylase (ACC), a marker of AMPK activity. Calcium chelator BAPTA-AM, calmodulin-dependent protein kinase kinase (CaMKK) inhibitor STO-069 and IP3 receptor antagonist 2-APB attenuated P2Y6R-mediated AMPK phosphorylation revealing involvement of intracellular Ca(2+) pathways. P2Y6R agonist induced insulin secretion at high glucose, which was reduced by AMPK siRNA. Thus, P2Y6R has a crucial role in β-cell function, suggesting its potential as a therapeutic target in diabetes.
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Affiliation(s)
- Ramachandran Balasubramanian
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Hiroshi Maruoka
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - P. Suresh Jayasekara
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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95
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Sriwijitkamol A, Musi N. Advances in the development of AMPK-activating compounds. Expert Opin Drug Discov 2013; 3:1167-76. [PMID: 23489075 DOI: 10.1517/17460441.3.10.1167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) is an energy sensing enzyme that controls glucose and lipid metabolism. OBJECTIVE This review summarizes the present data on AMPK as a pharmacologic target for the treatment of metabolic disorders. METHODS The mechanisms governing AMPK activity and how this enzyme controls different metabolic pathways are reviewed briefly, and details about the effect that AMPK activators have on glucose metabolism are provided. CONCLUSION Evidence obtained using the AMPK-activating compound 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) suggests that AMPK promotes glucose transport into skeletal muscles and that this enzyme inhibits hepatic glucose production. AICAR also induces fatty acid oxidation in muscle and inhibits cholesterol synthesis in the liver. The metabolic effects of AICAR on glucose and lipid metabolism indicate that AMPK may be a good pharmacologic target for the treatment of type 2 diabetes and hypercholesterolemia. Novel AMPK-specific compounds are allowing researchers to examine whether this enzyme is a useful pharmacologic target for the treatment of human disease and whether chronic activation of AMPK will be safe.
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Affiliation(s)
- Apiradee Sriwijitkamol
- University of Texas Health Science Center at San Antonio, Diabetes Division, San Antonio, Texas, USA
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96
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de Weille J, Fabre C, Bakalara N. Oxysterols in cancer cell proliferation and death. Biochem Pharmacol 2013; 86:154-60. [PMID: 23500545 DOI: 10.1016/j.bcp.2013.02.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 02/27/2013] [Accepted: 02/27/2013] [Indexed: 12/21/2022]
Abstract
Oxysterols have been shown to interfere with proliferation and cause the death of many cancer cell types, such as leukaemia, glioblastoma, colon, breast and prostate cancer cells, while they have little or no effect on senescent cells. The mechanisms by which oxysterols may influence proliferation are manifold: they control the transcription and the turnover of the key enzyme in cholesterol synthesis, 3-hydroxy-3-methylglutaryl CoA reductase, by binding to Insig-1, Insig-2 and liver X receptors. Oxysterols are thought to be generated in proportion to the rate of cholesterol synthesis. Although there is no consensus about the mechanism by which these oxysterols are generated in vivo, it clearly has to be ubiquitous. The 25- and the 27-cholesterol hydroxylases, present in almost all tissues, are possible candidates. Cholesterol uptake from lipoproteins, intracellular vesicle transport and lipid transfer are also modified by oxysterols. Oxysterols interfere with ERK, hedgehog and wnt pathways of proliferation and differentiation. When administered in vitro to cancer cell lines, oxysterols invariably both slow down proliferation and provoke cell death. Perhaps is it sufficient to stop proliferation of a cancer to provoke its eradication. Therefore, the two facets of oxysterol action that seem important for cancer treatment, cytostaticity and cytotoxicity, will be discussed.
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Affiliation(s)
- Jan de Weille
- Institut des Neurosciences de Montpellier, U1051 INSERM, 80 rue Augustin Fliche, 34295 Montpellier Cedex 05, France.
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97
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Kang H, Viollet B, Wu D. Genetic deletion of catalytic subunits of AMP-activated protein kinase increases osteoclasts and reduces bone mass in young adult mice. J Biol Chem 2013; 288:12187-96. [PMID: 23486478 DOI: 10.1074/jbc.m112.430389] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a key regulator of cellular and systemic energy homeostasis and a potential therapeutic target for the intervention of cancer and metabolic disorders. However, the role of AMPK in bone homeostasis remains incompletely understood. Here we assessed the skeletal phenotype of mice lacking catalytic subunits of AMPK and found that mice lacking AMPKα1 (Prkaa1(-/-)) or AMPKα2 (Prkaa2(-/-)) had reduced bone mass compared with the WT mice, although the reduction was less in Prkaa2(-/-) mice than in Prkaa1(-/-) mice. Static and dynamic bone histomorphometric analyses revealed that Prkaa1(-/-) mice had an elevated rate of bone remodeling because of increases in bone formation and resorption, whereas AMPKα2 KO-induced bone mass reduction was largely attributable to elevated bone resorption. In agreement with our in vivo results, AMPKα deficiency was associated with increased osteoclastogenesis in vitro. Moreover, we found that AMPKα1 inhibited the receptor activator of nuclear factor κB (RANK) signaling, providing an explanation for AMPK-mediated inhibition of osteoclastogenesis. Therefore, our findings further underscore the importance of AMPK in bone homeostasis, in particular osteoclastogenesis, in young adult mammals.
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Affiliation(s)
- Heeseog Kang
- Department of Pharmacology and Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, Connecticut 06520, USA.
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98
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Ju TC, Lin YS, Chern Y. Energy dysfunction in Huntington's disease: insights from PGC-1α, AMPK, and CKB. Cell Mol Life Sci 2012; 69:4107-20. [PMID: 22627493 PMCID: PMC11115139 DOI: 10.1007/s00018-012-1025-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/16/2012] [Accepted: 05/02/2012] [Indexed: 12/23/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. When the number of CAG repeats exceeds 36, the translated polyglutamine-expanded Htt protein interferes with the normal functions of many types of cellular machinery and causes cytotoxicity. Clinical symptoms include progressive involuntary movement disorders, psychiatric signs, cognitive decline, dementia, and a shortened lifespan. The most severe brain atrophy is observed in the striatum and cortex. Besides the well-characterized neuronal defects, recent studies showed that the functions of mitochondria and several key players in energy homeostasis are abnormally regulated during HD progression. Energy dysregulation thus is now recognized as an important pathogenic pathway of HD. This review focuses on the importance of three key molecular determinants (peroxisome proliferator-activated receptor-γ coactivator-1α, AMP-activated protein kinase, and creatine kinase B) of cellular energy homeostasis and their possible involvement in HD pathogenesis.
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Affiliation(s)
- Tz-Chuen Ju
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 11529 Taiwan
| | - Yow-Sien Lin
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 11529 Taiwan
| | - Yijuang Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 11529 Taiwan
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Merrill JF, Thomson DM, Hardman SE, Hepworth SD, Willie S, Hancock CR. Iron deficiency causes a shift in AMP-activated protein kinase (AMPK) subunit composition in rat skeletal muscle. Nutr Metab (Lond) 2012; 9:104. [PMID: 23171474 PMCID: PMC3575277 DOI: 10.1186/1743-7075-9-104] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 11/16/2012] [Indexed: 11/29/2022] Open
Abstract
Background As a cellular energy sensor, the 5’AMP-activated protein kinase (AMPK) is activated in response to energy stresses such as hypoxia and muscle contraction. To determine effects of iron deficiency on AMPK activation and signaling, as well as the AMPK subunit composition in skeletal muscle, rats were fed a control (C=50-58 mg/kg Fe) or iron deficient (ID=2-6 mg/kg Fe) diet for 6–8 wks. Results Their respective hematocrits were 47.5% ± 1.0 and 16.5% ± 0.6. Iron deficiency resulted in 28.3% greater muscle fatigue (p<0.01) in response to 10 min of stimulation (1 twitch/sec) and was associated with a greater reduction in phosphocreatine (C: Resting 24.1 ± 0.9 μmol/g, Stim 13.1 ± 1.5 μmol/g; ID: Resting 22.7 ± 1.0 μmol/g, Stim 3.2 ± 0.7 μmol/g; p<0.01) and ATP levels (C: Resting 5.89 ± 0.48 μmol/g, Stim 6.03 ± 0.35 μmol/g; ID: Resting 5.51 ± 0.20 μmol/g, Stim 4.19 ± 0.47 μmol/g; p<0.05). AMPK activation increased with stimulation in muscles of C and ID animals. A reduction in Cytochrome c and other iron-dependent mitochondrial proteins was observed in ID animals (p<0.01). The AMPK catalytic subunit (α) was examined because both isoforms are known to play different roles in responding to energy challenges. In ID animals, AMPKα2 subunit protein content was reduced to 71.6% of C (p<0.05), however this did not result in a significant difference in resting AMPKα2 activity. AMPKα1 protein was unchanged, however an overall increase in AMPKα1 activity was observed (C: 0.91 pmol/mg/min; ID: 1.63 pmol/mg/min; p<0.05). Resting phospho Acetyl CoA Carboxylase (pACC) was unchanged. In addition, we observed significant reductions in the β2 and γ3 subunits of AMPK in response to iron deficiency. Conclusions This study indicates that chronic iron deficiency causes a shift in the expression of AMPKα, β, and γ subunit composition. Iron deficiency also causes chronic activation of AMPK as well as an increase in AMPKα1 activity in exercised skeletal muscle.
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Affiliation(s)
- John F Merrill
- Department of Nutrition, Dietetics, and Food Science, Brigham Young University, Provo, Utah, USA.
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100
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Reduced AMPK-ACC and mTOR signaling in muscle from older men, and effect of resistance exercise. Mech Ageing Dev 2012; 133:655-64. [PMID: 23000302 DOI: 10.1016/j.mad.2012.09.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 08/20/2012] [Accepted: 09/07/2012] [Indexed: 11/20/2022]
Abstract
AMP-activated protein kinase (AMPK) is a key energy-sensitive enzyme that controls numerous metabolic and cellular processes. Mammalian target of rapamycin (mTOR) is another energy/nutrient-sensitive kinase that controls protein synthesis and cell growth. In this study we determined whether older versus younger men have alterations in the AMPK and mTOR pathways in skeletal muscle, and examined the effect of a long term resistance type exercise training program on these signaling intermediaries. Older men had decreased AMPKα2 activity and lower phosphorylation of AMPK and its downstream signaling substrate acetyl-CoA carboxylase (ACC). mTOR phosphylation also was reduced in muscle from older men. Exercise training increased AMPKα1 activity in older men, however, AMPKα2 activity, and the phosphorylation of AMPK, ACC and mTOR, were not affected. In conclusion, older men have alterations in the AMPK-ACC and mTOR pathways in muscle. In addition, prolonged resistance type exercise training induces an isoform-selective up regulation of AMPK activity.
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