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Han Y, Jin L, Wang L, Wei L, Tu C. Identification of PDK4 as Hub Gene for Diabetic Nephropathy Using Co-Expression Network Analysis. Kidney Blood Press Res 2023; 48:522-534. [PMID: 37385224 PMCID: PMC10619590 DOI: 10.1159/000531288] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 05/15/2023] [Indexed: 07/01/2023] Open
Abstract
INTRODUCTION Diabetic nephropathy (DN) is related to type 1 and type 2 diabetes. They are the leading cause of end-stage renal disease, but the underling specific pathogenesis of DN is not yet clear. Our study was conducted to explore how DN changed the transcriptome profiles in the kidney. METHODS The gene expression profile of microdissected glomeruli of 41 type 2 DN patients and 20 healthy controls were included. The sample dataset GSE96804 was obtained from the GEO database. Differentially expressed genes (DEGs) were analyzed in R with the limma package and the important modules were found by weighted gene co-expression network analysis (WGCNA) clustering. The modules were then analyzed based on Gene Ontology (GO) gene set enrichment analysis, and the hub genes were found out. We next validated the hub gene, PDK4, in a cell model of DN. We also constructed the PDK4-related PPI network to investigate the correlation between PDK4 expression and other genes. RESULTS Heatmap and volcano map were drawn to illustrate the mRNA expression profile of 1,204 DEGs in both samples of DN patients and the control group. Using WGCNA, we selected the blue module in which genes showed the strongest correlation with the phenotype and the smallest p value. We also identified PDK4 as a hub gene. PDK4 expression was upregulated in human diabetic kidney tissue. Moreover, PDK4 was speculated to play a role in glomerular basement membrane development and kidney development according to the enrichment of functions and signaling pathways. Furthermore, PDK4 and two key genes GSTA2 and G6PC protein expression were verified highly expressed in the cell model of DN. CONCLUSION During the pathogenesis of DN, many genes may change expression in a coordinated manner. The discovery of PDK4 as key gene using WGCNA is of great significance for the development of new treatment strategies to block the development of DN.
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Affiliation(s)
- Yuanyuan Han
- Center of Tree Shrew Germplasm Resources, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Liangzi Jin
- Center of Tree Shrew Germplasm Resources, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Liangzhi Wang
- Department of Internal Medicine, The Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Lan Wei
- Department of Internal Medicine, The Third Affiliated Hospital of Soochow University, Changzhou, China
| | - Chao Tu
- Department of Internal Medicine, The Third Affiliated Hospital of Soochow University, Changzhou, China
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2
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CB1 Ligand AM251 Induces Weight Loss and Fat Reduction in Addition to Increased Systemic Inflammation in Diet-Induced Obesity. Int J Mol Sci 2022; 23:ijms231911447. [PMID: 36232744 PMCID: PMC9569643 DOI: 10.3390/ijms231911447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 11/30/2022] Open
Abstract
Diet-induced obesity (DIO) reduces fatty acid oxidation in skeletal muscle and decreases circulating levels of adiponectin. Endocannabinoid signaling is overactive in obesity, with some effects abated by antagonism of cannabinoid receptor 1 (CB1). This research aimed to determine if treatment with the global CB1 antagonist/inverse agonist, AM251, in high-fat diet (HFD) fed rats influenced adiponectin signaling in skeletal muscle and a “browning” of white adipose tissue (WAT) defined by UCP1 expression levels. Male Sprague Dawley rats consumed an HFD (21% fat) for 9 weeks before receiving daily intraperitoneal injections with vehicle or AM251 (3 mg/kg) for 6 weeks. mRNA expression of genes involved in metabolic functions were measured in skeletal muscle and adipose tissue, and blood was harvested for the measurement of hormones and cytokines. Muscle citrate synthase activity was also measured. AM251 treatment decreased fat pad weight (epididymal, peri-renal, brown), and plasma levels of leptin, glucagon, ghrelin, and GLP-1, and increased PAI-1 along with a range of pro-inflammatory and anti-inflammatory cytokines; however, AM251 did not alter plasma adiponectin levels, skeletal muscle citrate synthase activity or mRNA expression of the genes measured in muscle. AM251 treatment had no effect on white fat UCP1 expression levels. AM251 decreased fat pad mass, altered plasma hormone levels, but did not induce browning of WAT defined by UCP1 mRNA levels or alter gene expression in muscle treated acutely with adiponectin, demonstrating the complexity of the endocannabinoid system and metabolism. The CB1 ligand AM251 increased systemic inflammation suggesting limitations on its use in metabolic disorders.
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Smith C, Lin X, Scott D, Brennan-Speranza TC, Al Saedi A, Moreno-Asso A, Woessner M, Bani Hassan E, Eynon N, Duque G, Levinger I. Uncovering the Bone-Muscle Interaction and Its Implications for the Health and Function of Older Adults (the Wellderly Project): Protocol for a Randomized Controlled Crossover Trial. JMIR Res Protoc 2021; 10:e18777. [PMID: 33835038 PMCID: PMC8065561 DOI: 10.2196/18777] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 11/29/2020] [Accepted: 12/01/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Bone and muscle are closely linked anatomically, biochemically, and metabolically. Acute exercise affects both bone and muscle, implying a crosstalk between the two systems. However, how these two systems communicate is still largely unknown. We will explore the role of undercarboxylated osteocalcin (ucOC) in this crosstalk. ucOC is involved in glucose metabolism and has a potential role in muscle maintenance and metabolism. OBJECTIVE The proposed trial will determine if circulating ucOC levels in older adults at baseline and following acute exercise are associated with parameters of muscle function and if the ucOC response to exercise varies between older adults with low muscle quality and those with normal or high muscle quality. METHODS A total of 54 men and women aged 60 years or older with no history of diabetes and warfarin and vitamin K use will be recruited. Screening tests will be performed, including those for functional, anthropometric, and clinical presentation. On the basis of muscle quality, a combined equation of lean mass (leg appendicular skeletal muscle mass in kg) and strength (leg press; one-repetition maximum), participants will be stratified into a high or low muscle function group and randomized into the controlled crossover acute intervention. Three visits will be performed approximately 7 days apart, and acute aerobic exercise, acute resistance exercise, and a control session (rest) will be completed in any order. Our primary outcome for this study is the effect of acute exercise on ucOC in older adults with low muscle function and those with high muscle function. RESULTS The trial is active and ongoing. Recruitment began in February 2018, and 38 participants have completed the study as of May 26, 2019. CONCLUSIONS This study will provide novel insights into bone and muscle crosstalk in older adults, potentially identifying new clinical biomarkers and mechanistic targets for drug treatments for sarcopenia and other related musculoskeletal conditions. TRIAL REGISTRATION Australia New Zealand Clinical Trials Registry ACTRN12618001756213; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375925. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID) DERR1-10.2196/18777.
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Affiliation(s)
- Cassandra Smith
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.,Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia
| | - Xuzhu Lin
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - David Scott
- Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia.,Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia.,Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia
| | - Tara C Brennan-Speranza
- School of Medical Sciences and School of Public Health, Faculty of Medicine and Health, University of Sydney, New South Wales, Australia
| | - Ahmed Al Saedi
- Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia.,Department of Medicine-Western Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Alba Moreno-Asso
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.,Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia
| | - Mary Woessner
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Ebrahim Bani Hassan
- Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia.,Department of Medicine-Western Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Nir Eynon
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Gustavo Duque
- Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia.,Department of Medicine-Western Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Itamar Levinger
- Australian Institute for Musculoskeletal Science, University of Melbourne and Western Health, Melbourne, VIC, Australia.,Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
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4
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Yamaguchi S, Moseley AC, Almeda-Valdes P, Stromsdorfer KL, Franczyk MP, Okunade AL, Patterson BW, Klein S, Yoshino J. Diurnal Variation in PDK4 Expression Is Associated With Plasma Free Fatty Acid Availability in People. J Clin Endocrinol Metab 2018; 103:1068-1076. [PMID: 29294006 PMCID: PMC6283414 DOI: 10.1210/jc.2017-02230] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 12/20/2017] [Indexed: 11/19/2022]
Abstract
CONTEXT Many biological pathways involved in regulating substrate metabolism display rhythmic oscillation patterns. In rodents, clock genes regulate circadian rhythms of metabolic genes and substrate metabolism. However, the interrelationships among substrate metabolism, metabolic genes, and clock genes have not been fully explored in people. OBJECTIVE We tested the hypothesis that the diurnal expression pattern of pyruvate dehydrogenase kinase 4 (PDK4), a key metabolic enzyme involved in fuel switching between glucose and free fatty acids (FFAs), is associated with plasma FFA concentration and clock genes. DESIGN AND METHODS We analyzed peripheral blood mononuclear cells (PBMCs), subcutaneous adipose tissue, and plasma samples obtained serially during 24 hours from metabolically healthy women (n = 10) and evaluated the interrelationships among PDK4, plasma FFA, and clock genes. We also determined the potential mechanisms responsible for PDK4 transcriptional regulation by using primary human PBMCs and adipocytes. RESULTS We found that PDK4 diurnal expression patterns were similar in PBMCs and adipose tissue (ρ = 0.84, P < 0.001). The diurnal variation in PBMC PDK4 expression correlated more strongly with plasma FFA and insulin (ρ = 0.86 and 0.63, respectively, both P < 0.001) concentrations than clock genes. Data obtained from primary culture experiments demonstrated that FFAs directly induced PDK4 gene expression, at least in part through activation of peroxisome proliferator-activated receptor α. CONCLUSIONS Our results suggest that plasma FFA availability is an important regulator of diurnal expression patterns of PDK4, and we identify a novel interaction between plasma FFA and cellular diurnal rhythms in regulating substrate metabolism.
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Affiliation(s)
- Shintaro Yamaguchi
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Anna C Moseley
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Paloma Almeda-Valdes
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Kelly L Stromsdorfer
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Michael P Franczyk
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Adewole L Okunade
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Bruce W Patterson
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Samuel Klein
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jun Yoshino
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
- Correspondence and Reprint Requests: Jun Yoshino, MD, PhD, Center for Human Nutrition, Department of Medicine, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8031, St. Louis, Missouri 63110. E-mail:
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5
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Yamane K, Indalao IL, Chida J, Yamamoto Y, Hanawa M, Kido H. Diisopropylamine dichloroacetate, a novel pyruvate dehydrogenase kinase 4 inhibitor, as a potential therapeutic agent for metabolic disorders and multiorgan failure in severe influenza. PLoS One 2014; 9:e98032. [PMID: 24865588 PMCID: PMC4035290 DOI: 10.1371/journal.pone.0098032] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/28/2014] [Indexed: 02/07/2023] Open
Abstract
Severe influenza is characterized by cytokine storm and multiorgan failure with metabolic energy disorders and vascular hyperpermeability. In the regulation of energy homeostasis, the pyruvate dehydrogenase (PDH) complex plays an important role by catalyzing oxidative decarboxylation of pyruvate, linking glycolysis to the tricarboxylic acid cycle and fatty acid synthesis, and thus its activity is linked to energy homeostasis. The present study tested the effects of diisopropylamine dichloroacetate (DADA), a new PDH kinase 4 (PDK4) inhibitor, in mice with severe influenza. Infection of mice with influenza A PR/8/34(H1N1) virus resulted in marked down-regulation of PDH activity and ATP level, with selective up-regulation of PDK4 in the skeletal muscles, heart, liver and lungs. Oral administration of DADA at 12-h intervals for 14 days starting immediately after infection significantly restored PDH activity and ATP level in various organs, and ameliorated disorders of glucose and lipid metabolism in the blood, together with marked improvement of survival and suppression of cytokine storm, trypsin up-regulation and viral replication. These results indicate that through PDK4 inhibition, DADA effectively suppresses the host metabolic disorder-cytokine cycle, which is closely linked to the influenza virus-cytokine-trypsin cycle, resulting in prevention of multiorgan failure in severe influenza.
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Affiliation(s)
- Kazuhiko Yamane
- Division of Enzyme Chemistry, Institute for Enzyme Research, The University of Tokushima, Tokushima, Japan
| | - Irene L Indalao
- Division of Enzyme Chemistry, Institute for Enzyme Research, The University of Tokushima, Tokushima, Japan
| | - Junji Chida
- Division of Enzyme Chemistry, Institute for Enzyme Research, The University of Tokushima, Tokushima, Japan
| | | | - Masaaki Hanawa
- R&D Department, Daiichi Sankyo Healthcare Co., Ltd., Tokyo, Japan
| | - Hiroshi Kido
- Division of Enzyme Chemistry, Institute for Enzyme Research, The University of Tokushima, Tokushima, Japan
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6
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Tao R, Xiong X, Harris RA, White MF, Dong XC. Genetic inactivation of pyruvate dehydrogenase kinases improves hepatic insulin resistance induced diabetes. PLoS One 2013; 8:e71997. [PMID: 23940800 PMCID: PMC3733847 DOI: 10.1371/journal.pone.0071997] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 07/11/2013] [Indexed: 12/12/2022] Open
Abstract
Pyruvate dehydrogenase kinases (PDK1-4) play a critical role in the inhibition of the mitochondrial pyruvate dehydrogenase complex especially when blood glucose levels are low and pyruvate can be conserved for gluconeogenesis. Under diabetic conditions, the Pdk genes, particularly Pdk4, are often induced, and the elevation of the Pdk4 gene expression has been implicated in the increased gluconeogenesis in the liver and the decreased glucose utilization in the peripheral tissues. However, there is no direct evidence yet to show to what extent that the dysregulation of hepatic Pdk genes attributes to hyperglycemia and insulin resistance in vivo. To address this question, we crossed Pdk2 or Pdk4 null mice with a diabetic model that is deficient in hepatic insulin receptor substrates 1 and 2 (Irs1/2). Metabolic analyses reveal that deletion of the Pdk4 gene had better improvement in hyperglycemia and glucose tolerance than knockout of the Pdk2 gene whereas the Pdk2 gene deletion showed better insulin tolerance as compared to the Pdk4 gene inactivation on the Irs1/2 knockout genetic background. To examine the specific hepatic effects of Pdks on diabetes, we also knocked down the Pdk2 or Pdk4 gene using specific shRNAs. The data also indicate that the Pdk4 gene knockdown led to better glucose tolerance than the Pdk2 gene knockdown. In conclusion, our data suggest that hepatic Pdk4 may be critically involved in the pathogenesis of diabetes.
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Affiliation(s)
- Rongya Tao
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Xiwen Xiong
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Robert A. Harris
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Richard Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana, United States of America
| | - Morris F. White
- Division of Endocrinology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Xiaocheng C. Dong
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail:
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7
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Cornall LM, Mathai ML, Hryciw DH, Simcocks AC, O'Brien PE, Wentworth JM, McAinch AJ. GPR119 regulates genetic markers of fatty acid oxidation in cultured skeletal muscle myotubes. Mol Cell Endocrinol 2013; 365:108-18. [PMID: 23069642 DOI: 10.1016/j.mce.2012.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 10/01/2012] [Accepted: 10/03/2012] [Indexed: 12/16/2022]
Abstract
Gene knockout and agonist studies indicate that activation of the G protein-coupled receptor, GPR119, protects against diet-induced obesity and insulin resistance. It is not known if GPR119 activation in skeletal muscle mediates these effects. To address this uncertainty, we measured GPR119 expression in skeletal muscle and determined the effects of PSN632408, a GPR119 agonist, on the expression of genes and proteins required for fatty acid and glucose oxidation in cultured myotubes. GPR119 expression was readily detected in rat skeletal muscle and mRNAs were induced by 12 weeks of high-fat feeding. Treatment of cultured mouse C₂C₁₂ myotubes with 5 μM PSN632408 or 0.5 mM palmitate reduced expression of mRNAs encoding fatty acid oxidation genes to similar extents. More so, treatment with PSN632408 decreased AMPKα (Thr172 phosphorylation) activity in the absence of palmitate and ACC (Ser79 phosphorylation) activity in the presence of palmitate. In human primary myotubes PSN632408 decreased expression of PDK4 and AMPKα2 mRNA in myotubes derived from obese donors. These data suggest GPR119 activation in skeletal muscle may impair fatty acid and glucose oxidation.
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MESH Headings
- Acids, Heterocyclic/pharmacology
- Adult
- Animals
- Body Mass Index
- Cells, Cultured
- Clone Cells
- Fatty Acids, Nonesterified/metabolism
- Female
- Gene Expression Regulation/drug effects
- Genetic Markers
- Glucose/metabolism
- Humans
- Male
- Mice
- Middle Aged
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Obesity, Morbid/genetics
- Obesity, Morbid/metabolism
- Obesity, Morbid/pathology
- Oxadiazoles/pharmacology
- Random Allocation
- Rats
- Rats, Sprague-Dawley
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
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Affiliation(s)
- L M Cornall
- Biomedical and Lifestyle Diseases Unit, School of Biomedical and Health Sciences, Victoria University, Melbourne 8001, Australia.
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Abstract
The pyruvate dehydrogenase complex (PDC) activity is crucial to maintains blood glucose and ATP levels, which largely depends on the phosphorylation status by pyruvate dehydrogenase kinase (PDK) isoenzymes. Although it has been reported that PDC is phosphorylated and inactivated by PDK2 and PDK4 in metabolically active tissues including liver, skeletal muscle, heart, and kidney during starvation and diabetes, the precise mechanisms by which expression of PDK2 and PDK4 are transcriptionally regulated still remains unclear. Insulin represses the expression of PDK2 and PDK4 via phosphorylation of FOXO through PI3K/Akt signaling pathway. Several nuclear hormone receptors activated due to fasting or increased fat supply, including peroxisome proliferator-activated receptors, glucocorticoid receptors, estrogen-related receptors, and thyroid hormone receptors, also participate in the up-regulation of PDK2 and PDK4; however, the endogenous ligands that bind those nuclear receptors have not been identified. It has been recently suggested that growth hormone, adiponectin, epinephrine, and rosiglitazone also control the expression of PDK4 in tissue-specific manners. In this review, we discuss several factors involved in the expressional regulation of PDK2 and PDK4, and introduce current studies aimed at providing a better understanding of the molecular mechanisms that underlie the development of metabolic diseases such as diabetes.
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Affiliation(s)
- Ji Yun Jeong
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - Nam Ho Jeoung
- Department of Fundamental Medical & Pharmaceutical Sciences, Catholic University of Daegu, Daegu, Korea
| | - Keun-Gyu Park
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - In-Kyu Lee
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
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9
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Moon SS, Lee JE, Lee YS, Kim SW, Jeoung NH, Lee IK, Kim JG. Association of pyruvate dehydrogenase kinase 4 gene polymorphisms with type 2 diabetes and metabolic syndrome. Diabetes Res Clin Pract 2012; 95:230-6. [PMID: 22019269 DOI: 10.1016/j.diabres.2011.09.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 09/20/2011] [Accepted: 09/29/2011] [Indexed: 01/16/2023]
Abstract
AIMS Pyruvate dehydrogenase kinase 4 (PDK4) plays a crucial role in glucose utilization and lipid metabolism by regulating the pyruvate dehydrogenase complex (PDC) and is an emerging therapeutic target for type 2 diabetes. To date, no study has specifically examined the relationship between PDK4 gene polymorphisms and type 2 diabetes or metabolic syndrome. METHODS The association of common single nucleotide polymorphisms (SNPs) was examined in PDK4 [-208A/G (rs10085637), IVS3+192C/T (rs3779478), IVS6+31A/G (rs2301630), IVS7+514A/G (rs12668651), IVS10+75C/T (rs10247649)] with type 2 diabetes and metabolic syndrome in 651 Korean subjects with type 2 diabetes and 350 nondiabetic Korean subjects. The association of these SNPs with clinical parameters related to metabolic syndromes including obesity, hyperglycemia, hypertension, and dyslipidemia was also examined. RESULTS No significant association was found between the studied SNPs and type 2 diabetes, metabolic syndrome, or clinical parameters. The PDK4 gene haplotype ACAGC showed a modest association with type 2 diabetes. However, the significance of this association was lost after considering for multiple comparisons. CONCLUSIONS PDK4 polymorphisms may not be associated with type 2 diabetes or metabolic syndrome. Further studies utilizing a larger study population are required to confirm these results.
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Affiliation(s)
- Seong-Su Moon
- Department of Internal medicine, Dongguk University School of Medicine, Gyeongju, South Korea.
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10
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Wan Z, Thrush AB, Legare M, Frier BC, Sutherland LN, Williams DB, Wright DC. Epinephrine-mediated regulation of PDK4 mRNA in rat adipose tissue. Am J Physiol Cell Physiol 2010; 299:C1162-70. [DOI: 10.1152/ajpcell.00188.2010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fatty acid reesterification in adipose tissue is dependent on the generation of glycerol 3-phosphate, and, at least in rodent adipose tissue, this appears to occur primarily through glyceroneogenesis. A key enzyme in this process is pyruvate dehydrogenase kinase 4 (PDK4). PDK4 is induced in white adipose tissue by thiazolidinediones (TZDs) and the inhibition or knockdown of PDK4 inhibits TZD-induced increases in glyceroneogenesis. Since TZDs have many unwanted side effects, we were interested in identifying alternative mechanisms that could regulate PDK4 mRNA expression in white adipose tissue. In this regard we hypothesized that exercise, fasting, and epinephrine would increase PDK4 mRNA levels in rat epididymal adipose tissue. We further postulated that the p38 mitogen-activated protein kinase (MAPK) and 5′-AMP-activated protein kinase (AMPK) signaling pathways would control PDK4 mRNA expression in cultured adipose tissue. Exercise, fasting, and in or ex vivo epinephrine treatment increased PDK4 mRNA levels. These perturbations did not increase the expression of PDK1, -2, or -3. Pyruvate dehydrogenase phosphorylation was increased after an overnight fast and 4 h after the cessation of exercise. In cultured adipose tissue, epinephrine increased p38 and AMPK signaling; however, the direct activation of AMPK by AICAR or metformin led to reductions in PDK4 mRNA levels. The p38 inhibitor SB202190 reduced epinephrine-mediated increases in p38 MAPK activation without altering hormone-sensitive lipase or AMPK phosphorylation or attenuating epinephrine-induced increases in lipolysis. Reductions in p38 MAPK signaling were associated with decreases in PDK4 mRNA expression. The inhibition of peroxisome proliferator-activated receptor-γ (PPARγ) also attenuated the induction of PDK4. Our results are the very first to demonstrate an epinephrine-mediated regulation of PDK4 mRNA levels in white adipose tissue and suggest that p38 MAPK and PPARγ could be involved in this pathway.
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Affiliation(s)
- Zhongxiao Wan
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - A. Brianne Thrush
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Melanie Legare
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Bruce C. Frier
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | | | - Deon B. Williams
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - David C. Wright
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
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