1
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Wang X, Zhang C, Zhao G, Yang K, Tao L. Obesity and lipid metabolism in the development of osteoporosis (Review). Int J Mol Med 2024; 54:61. [PMID: 38818830 DOI: 10.3892/ijmm.2024.5385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Accepted: 04/10/2024] [Indexed: 06/01/2024] Open
Abstract
Osteoporosis is a common bone metabolic disease that causes a heavy social burden and seriously threatens life. Improving osteogenic capacity is necessary to correct bone mass loss in the treatment of osteoporosis. Osteoblasts are derived from the differentiation of bone marrow mesenchymal stem cells, a process that opposes adipogenic differentiation. The peroxisome proliferator‑activated receptor γ and Wnt/β‑catenin signaling pathways mediate the mutual regulation of osteogenesis and adipogenesis. Lipid substances play an important role in the occurrence and development of osteoporosis. The content and proportion of lipids modulate the activity of immunocytes, mainly macrophages, and the secretion of inflammatory factors, such as IL‑1, IL‑6 and TNF‑α. These inflammatory effectors increase the activity and promote the differentiation of osteoclasts, which leads to bone imbalance and stronger bone resorption. Obesity also decreases the activity of antioxidases and leads to oxidative stress, thereby inhibiting osteogenesis. The present review starts by examining the bidirectional differentiation of BM‑MSCs, describes in detail the mechanism by which lipids affect bone metabolism, and discusses the regulatory role of inflammation and oxidative stress in this process. The review concludes that a reasonable adjustment of the content and proportion of lipids, and the alleviation of inflammatory storms and oxidative damage induced by lipid imbalances, will improve bone mass and treat osteoporosis.
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Affiliation(s)
- Xiaochuan Wang
- Department of Orthopedics, First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Chi Zhang
- Department of Orthopedics, First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Guang Zhao
- Department of Orthopedics, Fourth Hospital of China Medical University, Shenyang, Liaoning 110165, P.R. China
| | - Keda Yang
- Department of Orthopedics, First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Lin Tao
- Department of Orthopedics, First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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2
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Satapati S, Downes DP, Metzger D, Shankaran H, Talukdar S, Zhou Y, Ren Z, Chen M, Lim YH, Hatcher NG, Wen X, Sheth PR, McLaren DG, Previs SF. Using measures of metabolic flux to align screening and clinical development: Avoiding pitfalls to enable translational studies. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2022; 27:20-28. [PMID: 35058172 DOI: 10.1016/j.slasd.2021.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Screening campaigns, especially those aimed at modulating enzyme activity, often rely on measuring substrate→product conversions. Unfortunately, the presence of endogenous substrates and/or products can limit one's ability to measure conversions. As well, coupled detection systems, often used to facilitate optical readouts, are subject to interference. Stable isotope labeled substrates can overcome background contamination and yield a direct readout of enzyme activity. Not only can isotope kinetic assays enable early screening, but they can also be used to follow hit progression in translational (pre)clinical studies. Herein, we consider a case study surrounding lipid biology to exemplify how metabolic flux analyses can connect stages of drug development, caveats are highlighted to ensure reliable data interpretations. For example, when measuring enzyme activity in early biochemical screening it may be enough to quantify the formation of a labeled product. In contrast, cell-based and in vivo studies must account for variable exposure to a labeled substrate (or precursor) which occurs via tracer dilution and/or isotopic exchange. Strategies are discussed to correct for these complications. We believe that measures of metabolic flux can help connect structure-activity relationships with pharmacodynamic mechanisms of action and determine whether mechanistically differentiated biophysical interactions lead to physiologically relevant outcomes. Adoption of this logic may allow research programs to (i) build a critical bridge between primary screening and (pre)clinical development, (ii) elucidate biology in parallel with screening and (iii) suggest a strategy aimed at in vivo biomarker development.
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Affiliation(s)
- Santhosh Satapati
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Daniel P Downes
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Daniel Metzger
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Harish Shankaran
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Saswata Talukdar
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Yingjiang Zhou
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Zhao Ren
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Michelle Chen
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Yeon-Hee Lim
- Merck & Co., Inc, 213 E. Grand Ave, South San Francisco, CA, 94080, USA
| | - Nathan G Hatcher
- Merck & Co., Inc, 770 Sumneytown Pike, West Point, PA, 19486, USA
| | - Xiujuan Wen
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Payal R Sheth
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - David G McLaren
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Stephen F Previs
- Merck & Co., Inc, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA.
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3
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Masoodi M, Gastaldelli A, Hyötyläinen T, Arretxe E, Alonso C, Gaggini M, Brosnan J, Anstee QM, Millet O, Ortiz P, Mato JM, Dufour JF, Orešič M. Metabolomics and lipidomics in NAFLD: biomarkers and non-invasive diagnostic tests. Nat Rev Gastroenterol Hepatol 2021; 18:835-856. [PMID: 34508238 DOI: 10.1038/s41575-021-00502-9] [Citation(s) in RCA: 171] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/15/2021] [Indexed: 02/07/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide and is often associated with aspects of metabolic syndrome. Despite its prevalence and the importance of early diagnosis, there is a lack of robustly validated biomarkers for diagnosis, prognosis and monitoring of disease progression in response to a given treatment. In this Review, we provide an overview of the contribution of metabolomics and lipidomics in clinical studies to identify biomarkers associated with NAFLD and nonalcoholic steatohepatitis (NASH). In addition, we highlight the key metabolic pathways in NAFLD and NASH that have been identified by metabolomics and lipidomics approaches and could potentially be used as biomarkers for non-invasive diagnostic tests. Overall, the studies demonstrated alterations in amino acid metabolism and several aspects of lipid metabolism including circulating fatty acids, triglycerides, phospholipids and bile acids. Although we report several studies that identified potential biomarkers, few have been validated.
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Affiliation(s)
- Mojgan Masoodi
- Institute of Clinical Chemistry, Bern University Hospital, Bern, Switzerland.
| | | | - Tuulia Hyötyläinen
- School of Natural Sciences and Technology, Örebro University, Örebro, Sweden
| | - Enara Arretxe
- OWL Metabolomics, Bizkaia Technology Park, Derio, Spain
| | | | | | | | - Quentin M Anstee
- Clinical & Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Oscar Millet
- Precision Medicine & Metabolism, CIC bioGUNE, CIBERehd, BRTA, Bizkaia Technology Park, Derio, Spain
| | - Pablo Ortiz
- OWL Metabolomics, Bizkaia Technology Park, Derio, Spain
| | - Jose M Mato
- Precision Medicine & Metabolism, CIC bioGUNE, CIBERehd, BRTA, Bizkaia Technology Park, Derio, Spain
| | - Jean-Francois Dufour
- University Clinic of Visceral Surgery and Medicine, Inselspital Bern, Bern, Switzerland.,Hepatology, Department of BioMedical Research, University of Bern, Bern, Switzerland
| | - Matej Orešič
- School of Medical Sciences, Örebro University, Örebro, Sweden. .,Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland.
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Differential expression of gluconeogenic enzymes in early- and late-stage diabetes: the effect of Citrullus colocynthis (L.) Schrad. Seed extract on hyperglycemia and hyperlipidemia in Wistar-Albino rats model. CLINICAL PHYTOSCIENCE 2021. [DOI: 10.1186/s40816-021-00324-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
The medicinal plant Citrullus colocynthis (L.) Schrad. (C. colocynthis) may benefit patients at different phases of diabetes by attuning to contrasting situations. Our primary objective was to find the mechanism(s) behind the antidiabetic/anti-hyperlipidemic effects of C.colocynthis seed aqueous extract (CCAE) in two different stages of type 2 diabetes (T2D) in rats.
Methods
Fasting blood sugar (FBS) levels, body weights, and the degree of impaired glucose tolerance (IGT) were measured in healthy nondiabetic control rats (Con), as well as rats with early and late stages of T2D, denoted as ET2D and LT2D, respectively. CCAE was intraperitoneally (IP) injected for 28 days. In the end, the hepatic mRNA expression levels of the following genes were determined by RT-PCR: glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), insulin-dependent sterol regulatory element-binding protein-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), peroxisome proliferator-activated receptor alpha (PPARα), and carnitine palmitoyltransferase I (CPT1). The liver was examined by hematoxylin and eosin (H&E) and Oil-Red O staining. CCAE was partially analyzed by HPLC-DAD.
Results
ET2D and LT2D were characterized by differentially elevated FBS, deteriorated bodyweight, and significant IGT compared to Con. Hepatosteatoses of varying morphologies and higher hepatic expression of G6Pase than PRPCK in ET2D versus the opposite in LT2D further confirmed the divergent nature of metabolic aberrations. At the end of 28 days, the high levels of FBS, alkaline phosphatase (ALP), triglyceride (TG), urea, hepatic protein carbonyl content (PCC), and alanine and aspartate aminotransferases (AST and ALT, respectively) persisted in untreated LT2D. CCAE ameliorated oxidative stress and upregulated PPARα expression in diabetic groups and Con; it downregulated CPT1 expression in the LT2D group. CCAE’s ability to lower FBS and serum and hepatic TG in both ET2D and LT2D indicated its ability to act via different mechanisms. Ferulic acid (Fer A) and rutin hydrate (RH) were detected in CCAE.
Conclusion
CCAE lowered the FBS in ET2D via inhibiting the hepatic G6Pase expression (glycogenolysis). In LT2D, CCAE abated sugar levels by diverting PEPCK activity, preferably towards glyceroneogenesis than gluconeogenesis. The preserved triglyceride/fatty acid (TG/FA) cycle, the upregulated PPARα, and the downregulated CPT1 gene expressions reduced serum and hepatic TG.
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5
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Geidl-Flueck B, Hochuli M, Németh Á, Eberl A, Derron N, Köfeler HC, Tappy L, Berneis K, Spinas GA, Gerber PA. Fructose- and sucrose- but not glucose-sweetened beverages promote hepatic de novo lipogenesis: A randomized controlled trial. J Hepatol 2021; 75:46-54. [PMID: 33684506 DOI: 10.1016/j.jhep.2021.02.027] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 02/03/2021] [Accepted: 02/18/2021] [Indexed: 01/01/2023]
Abstract
BACKGROUND & AIMS Excessive fructose intake is associated with increased de novo lipogenesis, blood triglycerides, and hepatic insulin resistance. We aimed to determine whether fructose elicits specific effects on lipid metabolism independently of excessive caloric intake. METHODS A total of 94 healthy men were studied in this double-blind, randomized trial. They were assigned to daily consumption of sugar-sweetened beverages (SSBs) containing moderate amounts of fructose, sucrose (fructose-glucose disaccharide) or glucose (80 g/day) in addition to their usual diet or SSB abstinence (control group) for 7 weeks. De novo fatty acid (FA) and triglyceride synthesis, lipolysis and plasma free FA (FFA) oxidation were assessed by tracer methodology. RESULTS Daily intake of beverages sweetened with free fructose and fructose combined with glucose (sucrose) led to a 2-fold increase in basal hepatic fractional secretion rates (FSR) compared to control (median FSR %/day: sucrose 20.8 (p = 0.0015); fructose 19.7 (p = 0.013); control 9.1). Conversely, the same amounts of glucose did not change FSR (median of FSR %/day 11.0 (n.s.)). Fructose intake did not change basal secretion of newly synthesized VLDL-triglyceride, nor did it alter rates of peripheral lipolysis, nor total FA and plasma FFA oxidation. Total energy intake was similar across groups. CONCLUSIONS Regular consumption of both fructose- and sucrose-sweetened beverages in moderate doses - associated with stable caloric intake - increases hepatic FA synthesis even in a basal state; this effect is not observed after glucose consumption. These findings provide evidence of an adaptative response to regular fructose exposure in the liver. LAY SUMMARY This study investigated the metabolic effects of daily sugar-sweetened beverage consumption for several weeks in healthy lean men. It revealed that beverages sweetened with the sugars fructose and sucrose (glucose and fructose combined), but not glucose, increase the ability of the liver to produce lipids. This change may pave the way for further unfavorable effects on metabolic health. CLINICAL TRIAL REGISTRATION NUMBER NCT01733563.
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Affiliation(s)
- Bettina Geidl-Flueck
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland.
| | - Michel Hochuli
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland; Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism, Inselspital, Bern University Hospital and University of Bern, Switzerland
| | - Ágota Németh
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
| | - Anita Eberl
- Institute for Biomedicine and Health Sciences, Joanneum Research, Graz, Austria
| | - Nina Derron
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
| | - Harald C Köfeler
- Core Facility Mass Spectrometry, Medical University of Graz, Austria
| | - Luc Tappy
- Department of Physiology, University of Lausanne, Switzerland
| | - Kaspar Berneis
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
| | - Giatgen A Spinas
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
| | - Philipp A Gerber
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland
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6
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Carotti S, Aquilano K, Valentini F, Ruggiero S, Alletto F, Morini S, Picardi A, Antonelli-Incalzi R, Lettieri-Barbato D, Vespasiani-Gentilucci U. An overview of deregulated lipid metabolism in nonalcoholic fatty liver disease with special focus on lysosomal acid lipase. Am J Physiol Gastrointest Liver Physiol 2020; 319:G469-G480. [PMID: 32812776 DOI: 10.1152/ajpgi.00049.2020] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Obesity and type 2 diabetes are frequently complicated by excess fat accumulation in the liver, which is known as nonalcoholic fatty liver disease (NAFLD). In this context, liver steatosis develops as a result of the deregulation of pathways controlling de novo lipogenesis and fat catabolism. Recent evidences suggest the clinical relevance of a reduction in the activity of lysosomal acid lipase (LAL), which is a key enzyme for intracellular fat disposal, in patients with NAFLD. In this review, we provided a comprehensive overview of the critical steps in hepatic fat metabolism and alterations in these pathways in NAFLD, with a special focus on lipophagy and LAL activity. During NAFLD, hepatic fat metabolism is impaired at several levels, which is significantly contributed to by impaired lipophagy, in which reduced LAL activity may play an important role. For further research and intervention in NAFLD, targeting LAL activity may provide interesting perspectives.
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Affiliation(s)
- Simone Carotti
- Unit of Microscopic and Ultrastructural Anatomy, University Campus Bio-Medico, Rome, Italy
| | - Katia Aquilano
- Department of Biology, University of Rome, Tor Vergata, Rome, Italy
| | - Francesco Valentini
- Unit of Microscopic and Ultrastructural Anatomy, University Campus Bio-Medico, Rome, Italy
| | - Sergio Ruggiero
- Unit of Microscopic and Ultrastructural Anatomy, University Campus Bio-Medico, Rome, Italy
| | - Francesca Alletto
- Unit of Internal Medicine and Hepatology, University Campus Bio-Medico, Rome, Italy
| | - Sergio Morini
- Unit of Microscopic and Ultrastructural Anatomy, University Campus Bio-Medico, Rome, Italy
| | - Antonio Picardi
- Unit of Internal Medicine and Hepatology, University Campus Bio-Medico, Rome, Italy
| | | | - Daniele Lettieri-Barbato
- Department of Biology, University of Rome, Tor Vergata, Rome, Italy.,IRCCS Fondazione Santa Lucia, Rome, Italy
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7
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Seenappa V, Joshi MB, Satyamoorthy K. Intricate Regulation of Phosphoenolpyruvate Carboxykinase (PEPCK) Isoforms in Normal Physiology and Disease. Curr Mol Med 2020; 19:247-272. [PMID: 30947672 DOI: 10.2174/1566524019666190404155801] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND The phosphoenolpyruvate carboxykinase (PEPCK) isoforms are considered as rate-limiting enzymes for gluconeogenesis and glyceroneogenesis pathways. PEPCK exhibits several interesting features such as a) organelle-specific isoforms (cytosolic and a mitochondrial) in vertebrate clade, b) tissue-specific expression of isoforms and c) organism-specific requirement of ATP or GTP as a cofactor. In higher organisms, PEPCK isoforms are intricately regulated and activated through several physiological and pathological stimuli such as corticoids, hormones, nutrient starvation and hypoxia. Isoform-specific transcriptional/translational regulation and their interplay in maintaining glucose homeostasis remain to be fully understood. Mounting evidence indicates the significant involvement of PEPCK isoforms in physiological processes (development and longevity) and in the progression of a variety of diseases (metabolic disorders, cancer, Smith-Magenis syndrome). OBJECTIVE The present systematic review aimed to assimilate existing knowledge of transcriptional and translational regulation of PEPCK isoforms derived from cell, animal and clinical models. CONCLUSION Based on current knowledge and extensive bioinformatics analysis, in this review we have provided a comparative (epi)genetic understanding of PCK1 and PCK2 genes encompassing regulatory elements, disease-associated polymorphisms, copy number variations, regulatory miRNAs and CpG densities. We have also discussed various exogenous and endogenous modulators of PEPCK isoforms and their signaling mechanisms. A comprehensive review of existing knowledge of PEPCK regulation and function may enable identification of the underlying gaps to design new pharmacological strategies and interventions for the diseases associated with gluconeogenesis.
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Affiliation(s)
- Venu Seenappa
- School of Life Sciences, Manipal Academy of Higher Education, Manipal - 576104, India
| | - Manjunath B Joshi
- School of Life Sciences, Manipal Academy of Higher Education, Manipal - 576104, India
| | - Kapaettu Satyamoorthy
- School of Life Sciences, Manipal Academy of Higher Education, Manipal - 576104, India
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8
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Sasaki Y, Asahiyama M, Tanaka T, Yamamoto S, Murakami K, Kamiya W, Matsumura Y, Osawa T, Anai M, Fruchart JC, Aburatani H, Sakai J, Kodama T. Pemafibrate, a selective PPARα modulator, prevents non-alcoholic steatohepatitis development without reducing the hepatic triglyceride content. Sci Rep 2020; 10:7818. [PMID: 32385406 PMCID: PMC7210999 DOI: 10.1038/s41598-020-64902-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/05/2020] [Indexed: 12/30/2022] Open
Abstract
Non-alcoholic steatohepatitis (NASH) is characterized by macrovesicular steatosis with ballooning degeneration of hepatocytes, diffused lobular inflammation, and fibrosis. PPAR ligands are promising therapeutic agents in NASH; accordingly, we evaluated the effects of the first clinically available selective PPARα modulator, pemafibrate. We found that pemafibrate improves F4/80-positive macrophage accumulation, ballooning degeneration of hepatocytes, and the non-alcoholic fatty liver disease (NAFLD) activity score without affecting triglyceride (TG) accumulation in the liver of a mouse model of NASH (STAM). A global gene expression analysis indicated that pemafibrate enhances TG hydrolysis and fatty acid β-oxidation as well as re-esterification from dihydroxyacetone 3-phosphate and monoacylglycerol to TG. These changes are accompanied by the induction of genes involved in lipolysis and lipid droplet formation, along with an increased number and reduced size of lipid droplets in pemafibrate-treated livers. Pemafibrate reduced the expression of the cell adhesion molecule Vcam-1, myeloid cell markers, and inflammation- and fibrosis-related genes in STAM mice. Furthermore, pemafibrate significantly reduced VCAM-1 expression induced by high glucose in cultured human umbilical vein endothelial cells. These results suggest that pemafibrate prevents NASH development by reducing myeloid cell recruitment via interactions with liver sinusoidal endothelial cells, without altering hepatic TG accumulation.
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Affiliation(s)
- Yusuke Sasaki
- Department of Nuclear Receptor Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan.,Pharmaceutical Division, Kowa Company, Ltd., Tokyo, 189-0022, Japan
| | - Masato Asahiyama
- Pharmaceutical Division, Kowa Company, Ltd., Tokyo, 189-0022, Japan
| | - Toshiya Tanaka
- Department of Nuclear Receptor Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan.
| | - Shogo Yamamoto
- Genome Science Division, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
| | - Kentaro Murakami
- Department of Nuclear Receptor Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan.,Pharmaceutical Division, Kowa Company, Ltd., Tokyo, 189-0022, Japan
| | - Wakana Kamiya
- Department of Nuclear Receptor Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
| | - Yoshihiro Matsumura
- Division of Metabolic Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
| | - Tsuyoshi Osawa
- Division of Integrative Nutriomics and Oncology, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
| | - Motonobu Anai
- Department of Nuclear Receptor Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
| | | | - Hiroyuki Aburatani
- Genome Science Division, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
| | - Juro Sakai
- Division of Metabolic Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan.,Division of Molecular Physiology and Metabolism, Tohoku University Graduate School of Medicine, Sendai, Miyagi, 980-8575, Japan
| | - Tatsuhiko Kodama
- Department of Nuclear Receptor Medicine, Laboratories for Systems Biology and Medicine (LSBM) at the Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo, 153-8904, Japan
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9
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De Souza LR, Berger H, Retnakaran R, Vlachou PA, Maguire JL, Nathens AB, Connelly PW, Ray JG. Non-Alcoholic Fatty Liver Disease in Early Pregnancy Predicts Dysglycemia in Mid-Pregnancy: Prospective Study. Am J Gastroenterol 2016; 111:665-70. [PMID: 26977755 DOI: 10.1038/ajg.2016.43] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/02/2016] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Non-alcoholic fatty liver disease (NAFLD) is mediated by insulin resistance, as is gestational diabetes mellitus (GDM). NAFLD has not been studied in relation to GDM. The objective of this study was to assess the association between first-trimester sonographic findings of NAFLD, and both dysglycemia and GDM in mid-pregnancy. METHODS We followed a prospective cohort design at a large obstetrics clinic in Toronto, Ontario with 476 women enrolled in early pregnancy. NAFLD was assessed by ultrasound at 11-14 weeks gestation, and standardized images were independently scored by two ultrasonographers for the presence of hepatorenal contrast (one finding) and/or blurring of the intrahepatic vessels (one finding), relative to neither being present. Logistic regression analysis was used to generate odds ratios (ORs) and 95% confidence interval (CI) for the relation between 0, 1, or 2 sonographic findings of NAFLD and the composite outcome of impaired fasting glucose, impaired glucose tolerance, or GDM at 24-28 weeks gestation, determined by a fasting 75-g oral glucose tolerance test. ORs were adjusted (aOR) for maternal age, ethnicity, first-degree relative with type 2 DM, body mass index (BMI) at 11-14 weeks gestation, and change in BMI from 11-14 to 24-28 weeks gestation. RESULTS Fifty out of 476 women (10.5%) developed the composite outcome. The presence of 1 (aOR 2.0, 95% CI: 1.0-4.1) or 2 (aOR 2.9, 95% CI: 1.0-18.4) sonographic features of NAFLD predicted the composite outcome. Limiting the analysis to ≥1 feature vs. none, the aOR was 2.2 (95% CI: 1.1-4.3). CONCLUSIONS Sonographic assessment of NAFLD is a semiquantitative measure, with limited ability to detect small amounts of hepatic steatosis, or to distinguish various stages of NAFLD. First-trimester sonographic evidence of NAFLD predicts dysglycemia in mid-pregnancy.
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Affiliation(s)
- Leanne R De Souza
- Department of Obstetrics and Gynecology, St Michael's Hospital, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Howard Berger
- Department of Obstetrics and Gynecology, St Michael's Hospital, Toronto, Ontario, Canada.,Keenan Research Centre for Biomedical Science of St Michael's Hospital, Toronto, Ontario, Canada
| | - Ravi Retnakaran
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Paraskevi A Vlachou
- Department of Medical Imaging, St Michael's Hospital, Toronto, Ontario, Canada
| | - Jonathon L Maguire
- Keenan Research Centre for Biomedical Science of St Michael's Hospital, Toronto, Ontario, Canada
| | - Avery B Nathens
- Department of Surgery, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada
| | - Philip W Connelly
- Keenan Research Centre for Biomedical Science of St Michael's Hospital, Toronto, Ontario, Canada.,Department of Medicine, St Michael's Hospital, Toronto, Ontario, Canada
| | - Joel G Ray
- Department of Obstetrics and Gynecology, St Michael's Hospital, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.,Keenan Research Centre for Biomedical Science of St Michael's Hospital, Toronto, Ontario, Canada.,Department of Medicine, St Michael's Hospital, Toronto, Ontario, Canada.,Department of Health Policy Management Evaluation, University of Toronto, Toronto, Ontario, Canada
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10
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Saponaro C, Gaggini M, Carli F, Gastaldelli A. The Subtle Balance between Lipolysis and Lipogenesis: A Critical Point in Metabolic Homeostasis. Nutrients 2015; 7:9453-74. [PMID: 26580649 PMCID: PMC4663603 DOI: 10.3390/nu7115475] [Citation(s) in RCA: 299] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/19/2015] [Accepted: 10/29/2015] [Indexed: 12/17/2022] Open
Abstract
Excessive accumulation of lipids can lead to lipotoxicity, cell dysfunction and alteration in metabolic pathways, both in adipose tissue and peripheral organs, like liver, heart, pancreas and muscle. This is now a recognized risk factor for the development of metabolic disorders, such as obesity, diabetes, fatty liver disease (NAFLD), cardiovascular diseases (CVD) and hepatocellular carcinoma (HCC). The causes for lipotoxicity are not only a high fat diet but also excessive lipolysis, adipogenesis and adipose tissue insulin resistance. The aims of this review are to investigate the subtle balances that underlie lipolytic, lipogenic and oxidative pathways, to evaluate critical points and the complexities of these processes and to better understand which are the metabolic derangements resulting from their imbalance, such as type 2 diabetes and non alcoholic fatty liver disease.
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Affiliation(s)
- Chiara Saponaro
- Cardiometabolic Risk Unit, Institute of Clinical Physiology, CNR, via Moruzzi, 1 56124 Pisa, Italy.
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, 53100 Siena, Italy.
| | - Melania Gaggini
- Cardiometabolic Risk Unit, Institute of Clinical Physiology, CNR, via Moruzzi, 1 56124 Pisa, Italy.
- Dipartimento di Patologia Chirurgica, Molecolare Medica e di Area Critica, Università di Pisa, 56126 Pisa, Italy.
| | - Fabrizia Carli
- Cardiometabolic Risk Unit, Institute of Clinical Physiology, CNR, via Moruzzi, 1 56124 Pisa, Italy.
| | - Amalia Gastaldelli
- Cardiometabolic Risk Unit, Institute of Clinical Physiology, CNR, via Moruzzi, 1 56124 Pisa, Italy.
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11
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Early-life exposure to high-fat diet may predispose rats to gender-specific hepatic fat accumulation by programming Pepck expression. J Nutr Biochem 2015; 26:433-40. [DOI: 10.1016/j.jnutbio.2014.10.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 09/28/2014] [Accepted: 10/16/2014] [Indexed: 12/25/2022]
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12
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Previs SF, McLaren DG, Wang SP, Stout SJ, Zhou H, Herath K, Shah V, Miller PL, Wilsie L, Castro-Perez J, Johns DG, Cleary MA, Roddy TP. New methodologies for studying lipid synthesis and turnover: looking backwards to enable moving forwards. Biochim Biophys Acta Mol Basis Dis 2013; 1842:402-13. [PMID: 23707557 DOI: 10.1016/j.bbadis.2013.05.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/11/2013] [Accepted: 05/13/2013] [Indexed: 12/26/2022]
Abstract
Our ability to understand the pathogenesis of problems surrounding lipid accretion requires attention towards quantifying lipid kinetics. In addition, studies of metabolic flux should also help unravel mechanisms that lead to imbalances in inter-organ lipid trafficking which contribute to dyslipidemia and/or peripheral lipid accumulation (e.g. hepatic fat deposits). This review aims to outline the development and use of novel methods for studying lipid kinetics in vivo. Although our focus is directed towards some of the approaches that are currently reported in the literature, we include a discussion of the older literature in order to put "new" methods in better perspective and inform readers of valuable historical research. Presumably, future advances in understanding lipid dynamics will benefit from a careful consideration of the past efforts, where possible we have tried to identify seminal papers or those that provide clear data to emphasize essential points. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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Affiliation(s)
- Stephen F Previs
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
| | - David G McLaren
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Sheng-Ping Wang
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Steven J Stout
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Haihong Zhou
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Kithsiri Herath
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Vinit Shah
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Paul L Miller
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Larissa Wilsie
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Jose Castro-Perez
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Douglas G Johns
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Michele A Cleary
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
| | - Thomas P Roddy
- Molecular Biomarkers, Merck, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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13
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Jin ES, Sherry AD, Malloy CR. Metabolism of glycerol, glucose, and lactate in the citric acid cycle prior to incorporation into hepatic acylglycerols. J Biol Chem 2013; 288:14488-14496. [PMID: 23572519 DOI: 10.1074/jbc.m113.461947] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During hepatic lipogenesis, the glycerol backbone of acylglycerols originates from one of three sources: glucose, glycerol, or substrates passing through the citric acid cycle via glyceroneogenesis. The relative contribution of each substrate source to glycerol in rat liver acylglycerols was determined using (13)C-enriched substrates and NMR. Animals received a fixed mixture of glucose, glycerol, and lactate; one group received [U-(13)C6]glucose, another received [U-(13)C3]glycerol, and the third received [U-(13)C3]lactate. After 3 h, the livers were harvested to extract fats, and the glycerol moiety from hydrolyzed acylglycerols was analyzed by (13)C NMR. In either fed or fasted animals, glucose and glycerol provided the majority of the glycerol backbone carbons, whereas the contribution of lactate was small. In fed animals, glucose contributed >50% of the total newly synthesized glycerol backbone, and 35% of this contribution occurred after glucose had passed through the citric acid cycle. By comparison, the glycerol contribution was ~40%, and of this, 17% of the exogenous glycerol passed first through the cycle. In fasted animals, exogenous glycerol became the major contributor to acylglycerols. The contribution from exogenous lactate did increase in fasted animals, but its overall contribution remained small. The contributions of glucose and glycerol that had passed through the citric acid cycle first increased in fasted animals from 35 to 71% for glucose and from 17 to 24% for glycerol. Thus, a substantial fraction from both substrate sources passed through the cycle prior to incorporation into the glycerol moiety of acylglycerols in the liver.
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Affiliation(s)
- Eunsook S Jin
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390.
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Veterans Affairs North Texas Health Care System, Dallas, Texas 75216
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14
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Castro-Perez JM, Roddy TP, Shah V, McLaren DG, Wang SP, Jensen K, Vreeken RJ, Hankemeier T, Johns DG, Previs SF, Hubbard BK. Identifying Static and Kinetic Lipid Phenotypes by High Resolution UPLC–MS: Unraveling Diet-Induced Changes in Lipid Homeostasis by Coupling Metabolomics and Fluxomics. J Proteome Res 2011; 10:4281-90. [DOI: 10.1021/pr200480g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jose M. Castro-Perez
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
- Division of Analytical Biosciences, LACDR, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Thomas P. Roddy
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - Vinit Shah
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - David G. McLaren
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - Sheng-Ping Wang
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - Kristian Jensen
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - Rob J. Vreeken
- Division of Analytical Biosciences, LACDR, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
- Netherlands Metabolomics Centre, LACDR, Leiden University, P.O. Box 9502, 2300RA Leiden, The Netherlands
| | - Thomas Hankemeier
- Division of Analytical Biosciences, LACDR, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
- Netherlands Metabolomics Centre, LACDR, Leiden University, P.O. Box 9502, 2300RA Leiden, The Netherlands
| | - Douglas G. Johns
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - Stephen F. Previs
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
| | - Brian K. Hubbard
- Department of Cardiovascular Diseases − Atherosclerosis Rahway, Merck Research Laboratories, New Jersey 07065, United States
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15
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Jeoung NH, Harris RA. Role of pyruvate dehydrogenase kinase 4 in regulation of blood glucose levels. KOREAN DIABETES JOURNAL 2010; 34:274-83. [PMID: 21076574 PMCID: PMC2972486 DOI: 10.4093/kdj.2010.34.5.274] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the well-fed state a relatively high activity of the pyruvate dehydrogenase complex (PDC) reduces blood glucose levels by directing the carbon of pyruvate into the citric acid cycle. In the fasted state a relatively low activity of the PDC helps maintain blood glucose levels by conserving pyruvate and other three carbon compounds for gluconeogenesis. The relative activities of the pyruvate dehydrogenase kinases (PDKs) and the opposing pyruvate dehydrogenase phosphatases determine the activity of PDC in the fed and fasted states. Up regulation of PDK4 is largely responsible for inactivation of PDC in the fasted state. PDK4 knockout mice have lower fasting blood glucose levels than wild type mice, proving that up regulation of PDK4 is important for normal glucose homeostasis. In type 2 diabetes, up regulation of PDK4 also inactivates PDC, which promotes gluconeogenesis and thereby contributes to the hyperglycemia characteristic of this disease. When fed a high fat diet, wild type mice develop fasting hyperglycemia but PDK4 knockout mice remain euglycemic, proving that up regulation of PDK4 contributes to hyperglycemia in diabetes. These finding suggest PDK4 inhibitors might prove useful in the treatment of type 2 diabetes.
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Affiliation(s)
- Nam Ho Jeoung
- Department of Fundamental Medical and Pharmaceutical Sciences, Catholic University of Daegu, Gyeongsan, Korea
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16
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Yang J, Kalhan SC, Hanson RW. What is the metabolic role of phosphoenolpyruvate carboxykinase? J Biol Chem 2009; 284:27025-9. [PMID: 19636077 DOI: 10.1074/jbc.r109.040543] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jianqi Yang
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4936, USA
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17
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Nye C, Kim J, Kalhan SC, Hanson RW. Reassessing triglyceride synthesis in adipose tissue. Trends Endocrinol Metab 2008; 19:356-61. [PMID: 18929494 DOI: 10.1016/j.tem.2008.08.003] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 08/11/2008] [Accepted: 08/12/2008] [Indexed: 10/21/2022]
Abstract
The synthesis and breakdown of triglycerides in adipose tissue and muscle is a crucial element of energy metabolism because it ensures that adequate fuel is available during starvation. Triglyceride turnover determines the availability of fatty acids for utilization by mammalian tissues, and any dysfunction in this process can lead to alterations in glucose metabolism, insulin resistance and type 2 diabetes. Our understanding of the reactions involved in triglyceride synthesis is currently being reassessed, primarily because of the recently identified role that re-esterification of fatty acids plays in triglyceride deposition and, thus, in controlling fatty-acid availability. Here, we review recent information on triglyceride synthesis and introduce the pathway of glyceroneogenesis as an important and highly regulated source of glyceride-glycerol in adipose tissue.
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Affiliation(s)
- Colleen Nye
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106-3549, USA
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18
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Nye CK, Hanson RW, Kalhan SC. Glyceroneogenesis is the dominant pathway for triglyceride glycerol synthesis in vivo in the rat. J Biol Chem 2008; 283:27565-27574. [PMID: 18662986 PMCID: PMC2562054 DOI: 10.1074/jbc.m804393200] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 07/22/2008] [Indexed: 12/13/2022] Open
Abstract
Triglyceride synthesis in mammalian tissues requires glycerol 3-phosphate as the source of triglyceride glycerol. In this study the relative contribution of glyceroneogenesis and glycolysis to triglyceride glycerol synthesis was quantified in vivo in adipose tissue, skeletal muscle, and liver of the rat in response to a chow diet (controls), 48-h fast, and lipogenic (high sucrose) diet. The rate of glyceroneogenesis was quantified using the tritium ([(3)H(2)]O) labeling of body water, and the contribution of glucose, via glycolysis, was determined using a [U-(14)C]glucose tracer. In epididymal and mesenteric adipose tissue of control rats, glyceroneogenesis accounted for approximately 90% of triglyceride glycerol synthesis. Fasting for 48 h did not alter glyceroneogenesis in adipose tissue, whereas the contribution of glucose was negligible. In response to sucrose feeding, the synthesis of triglyceride glycerol via both glyceroneogenesis and glycolysis nearly doubled (versus controls); however, glyceroneogenesis remained quantitatively higher as compared with the contribution of glucose. Enhancement of triglyceride-fatty acid cycling by epinephrine infusion resulted in a higher rate of glyceroneogenesis in adipose tissue, as compared with controls, whereas the contribution of glucose via glycolysis was not measurable. Glyceroneogenesis provided the majority of triglyceride glycerol in the gastrocnemius and soleus. In the liver the fractional contribution of glyceroneogenesis remained constant (approximately 60%) under all conditions and was higher than that of glucose. Thus, glyceroneogenesis, in contrast to glucose, via glycolysis, is quantitatively the predominant source of triglyceride glycerol in adipose tissue, skeletal muscle, and liver of the rat during fasting and high sucrose feeding.
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Affiliation(s)
- Colleen K Nye
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Departments of Gastroenterology and Pathobiology, Cleveland Clinic, Cleveland, Ohio 44195
| | - Richard W Hanson
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Departments of Gastroenterology and Pathobiology, Cleveland Clinic, Cleveland, Ohio 44195
| | - Satish C Kalhan
- Departments of Gastroenterology and Pathobiology, Cleveland Clinic, Cleveland, Ohio 44195; Department of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic, Cleveland, Ohio 44195.
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