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Kajani S, Laker RC, Ratkova E, Will S, Rhodes CJ. Hepatic glucagon action: beyond glucose mobilization. Physiol Rev 2024; 104:1021-1060. [PMID: 38300523 DOI: 10.1152/physrev.00028.2023] [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: 07/11/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
Glucagon's ability to promote hepatic glucose production has been known for over a century, with initial observations touting this hormone as a diabetogenic agent. However, glucagon receptor agonism [when balanced with an incretin, including glucagon-like peptide 1 (GLP-1) to dampen glucose excursions] is now being developed as a promising therapeutic target in the treatment of metabolic diseases, like metabolic dysfunction-associated steatotic disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH), and may also have benefit for obesity and chronic kidney disease. Conventionally regarded as the opposing tag-team partner of the anabolic mediator insulin, glucagon is gradually emerging as more than just a "catabolic hormone." Glucagon action on glucose homeostasis within the liver has been well characterized. However, growing evidence, in part thanks to new and sensitive "omics" technologies, has implicated glucagon as more than just a "glucose liberator." Elucidation of glucagon's capacity to increase fatty acid oxidation while attenuating endogenous lipid synthesis speaks to the dichotomous nature of the hormone. Furthermore, glucagon action is not limited to just glucose homeostasis and lipid metabolism, as traditionally reported. Glucagon plays key regulatory roles in hepatic amino acid and ketone body metabolism, as well as mitochondrial turnover and function, indicating broader glucagon signaling consequences for metabolic homeostasis mediated by the liver. Here we examine the broadening role of glucagon signaling within the hepatocyte and question the current dogma, to appreciate glucagon as more than just that "catabolic hormone."
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Affiliation(s)
- Sarina Kajani
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
| | - Rhianna C Laker
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
| | - Ekaterina Ratkova
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Mölndal, Sweden
| | - Sarah Will
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
| | - Christopher J Rhodes
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
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2
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Dietsche KB, Magge SN, Dixon SA, Davis FS, Krenek A, Chowdhury A, Mabundo L, Stagliano M, Courville AB, Yang S, Turner S, Cai H, Kasturi K, Sherman AS, Ha J, Shouppe E, Walter M, Walter PJ, Chen KY, Brychta RJ, Peer C, Zeng Y, Figg W, Cogen F, Estrada DE, Chacko S, Chung ST. Glycemia and Gluconeogenesis With Metformin and Liraglutide: A Randomized Trial in Youth-onset Type 2 Diabetes. J Clin Endocrinol Metab 2024; 109:1361-1370. [PMID: 37967247 PMCID: PMC11031226 DOI: 10.1210/clinem/dgad669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/02/2023] [Accepted: 11/13/2023] [Indexed: 11/17/2023]
Abstract
OBJECTIVE Elevated rates of gluconeogenesis are an early pathogenic feature of youth-onset type 2 diabetes (Y-T2D), but targeted first-line therapies are suboptimal, especially in African American (AA) youth. We evaluated glucose-lowering mechanisms of metformin and liraglutide by measuring rates of gluconeogenesis and β-cell function after therapy in AA Y-T2D. METHODS In this parallel randomized clinical trial, 22 youth with Y-T2D-age 15.3 ± 2.1 years (mean ± SD), 68% female, body mass index (BMI) 40.1 ± 7.9 kg/m2, duration of diagnosis 1.8 ± 1.3 years-were randomized to metformin alone (Met) or metformin + liraglutide (Lira) (Met + Lira) and evaluated before and after 12 weeks. Stable isotope tracers were used to measure gluconeogenesis [2H2O] and glucose production [6,6-2H2]glucose after an overnight fast and during a continuous meal. β-cell function (sigma) and whole-body insulin sensitivity (mSI) were assessed during a frequently sampled 2-hour oral glucose tolerance test. RESULTS At baseline, gluconeogenesis, glucose production, and fasting and 2-hour glucose were comparable in both groups, though Met + Lira had higher hemoglobin A1C. Met + Lira had a greater decrease from baseline in fasting glucose (-2.0 ± 1.3 vs -0.6 ± 0.9 mmol/L, P = .008) and a greater increase in sigma (0.72 ± 0.68 vs -0.05 ± 0.71, P = .03). The change in fractional gluconeogenesis was similar between groups (Met + Lira: -0.36 ± 9.4 vs Met: 0.04 ± 12.3%, P = .9), and there were no changes in prandial gluconeogenesis or mSI. Increased glucose clearance in both groups was related to sigma (r = 0.63, P = .003) but not gluconeogenesis or mSI. CONCLUSION Among Y-T2D, metformin with or without liraglutide improved glycemia but did not suppress high rates of gluconeogenesis. Novel therapies that will enhance β-cell function and target the elevated rates of gluconeogenesis in Y-T2D are needed.
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Affiliation(s)
- Katrina B Dietsche
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Sheela N Magge
- Division of Pediatric Endocrinology and Diabetes, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sydney A Dixon
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Faith S Davis
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrea Krenek
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Aruba Chowdhury
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Lilian Mabundo
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Michael Stagliano
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Amber B Courville
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Shanna Yang
- Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sara Turner
- Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hongyi Cai
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Kannan Kasturi
- Division of Pediatric Endocrinology, Essentia Health, Duluth, MN 55805, USA
| | - Arthur S Sherman
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Joon Ha
- Department of Mathematics, Howard University, Washington, DC 20059, USA
| | - Eileen Shouppe
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Mary Walter
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter J Walter
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Kong Y Chen
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert J Brychta
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
| | - Cody Peer
- Clinical Pharmacology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yi Zeng
- Clinical Pharmacology Laboratory, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - William Figg
- Clinical Pharmacology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Fran Cogen
- Division of Endocrinology and Diabetes, Children's National Hospital, Washington, DC 20010, USA
| | - D Elizabeth Estrada
- Division of Endocrinology and Diabetes, Children's National Hospital, Washington, DC 20010, USA
| | - Shaji Chacko
- Department of Pediatrics, Children's Nutrition Research Center and Division of Pediatric Endocrinology and Metabolism, U.S. Department of Agriculture/Agricultural Research Service, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stephanie T Chung
- National Institute of Diabetes, Digestive and Kidney Diseases/National Institutes of Health, Bethesda, MD 20892, USA
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Lee KS, Lee YH, Lee SG. Alanine to glycine ratio is a novel predictive biomarker for type 2 diabetes mellitus. Diabetes Obes Metab 2024; 26:980-988. [PMID: 38073420 DOI: 10.1111/dom.15395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 11/01/2023] [Accepted: 11/21/2023] [Indexed: 02/06/2024]
Abstract
AIM We aimed to evaluate the metabolite ratios that could predict the clinical incidence or remission of type 2 diabetes mellitus (T2D). METHODS The Cox proportional hazards regression model was used to assess 1813 individuals without T2D to test the predictive value of metabolite ratios for T2D incidence and 451 newly diagnosed T2D for remission. The receiver operating characteristic curve analysis was performed to determine the best cut-off values for the metabolite ratios. Survival analyses were performed to compare the four subgroups defined by baseline metabolite ratios and clinical status of obesity. RESULTS The alanine/glycine was the most significant marker for T2D incidence (hazard ratio per SD: 1.24; p < .001). On the other hand, metabolite hydroxy sphingomyelin C22:2 was most specific for T2D remission (hazard ratio per SD: 1.32; p = .029). Survival analysis of T2D incidence among the subgroups defined by the combination of alanine/glycine and obesity showed the group with a high alanine/glycine and obesity had the highest risk of T2D incidence (p < .001). The alanine/glycine as a T2D risk marker was also validated in the independent external data. CONCLUSIONS The combination of obesity and the alanine/glycine ratio can be used to evaluate the diabetes risk.
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Affiliation(s)
- Kwang Seob Lee
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Yong-Ho Lee
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, South Korea
- Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, South Korea
| | - Sang-Guk Lee
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea
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Subramanian V, Bagger JI, Harihar V, Holst JJ, Knop FK, Villsbøll T. An extended minimal model of OGTT: estimation of α- and β-cell dysfunction, insulin resistance, and the incretin effect. Am J Physiol Endocrinol Metab 2024; 326:E182-E205. [PMID: 38088864 DOI: 10.1152/ajpendo.00278.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/27/2023] [Accepted: 12/07/2023] [Indexed: 12/20/2023]
Abstract
Loss of insulin sensitivity, α- and β-cell dysfunction, and impairment in incretin effect have all been implicated in the pathophysiology of type 2 diabetes (T2D). Parsimonious mathematical models are useful in quantifying parameters related to the pathophysiology of T2D. Here, we extend the minimum model developed to describe the glucose-insulin-glucagon dynamics in the isoglycemic intravenous glucose infusion (IIGI) experiment to the oral glucose tolerance test (OGTT). The extended model describes glucose and hormone dynamics in OGTT including the contribution of the incretin hormones, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-1 (GLP-1), to insulin secretion. A new function describing glucose arrival from the gut is introduced. The model is fitted to OGTT data from eight individuals with T2D and eight weight-matched controls (CS) without diabetes to obtain parameters related to insulin sensitivity, β- and α-cell function. The parameters, i.e., measures of insulin sensitivity, a1, suppression of glucagon secretion, k1, magnitude of glucagon secretion, γ2, and incretin-dependent insulin secretion, γ3, were found to be different between CS and T2D with P values < 0.002, <0.017, <0.009, <0.004, respectively. A new rubric for estimating the incretin effect directly from modeling the OGTT is presented. The average incretin effect correlated well with the experimentally determined incretin effect with a Spearman rank test correlation coefficient of 0.67 (P < 0.012). The average incretin effect was found to be different between CS and T2D (P < 0.032). The developed model is shown to be effective in quantifying the factors relevant to T2D pathophysiology.NEW & NOTEWORTHY A new extended model of oral glucose tolerance test (OGTT) has been developed that includes glucagon dynamics and incretin contribution to insulin secretion. The model allows the estimation of parameters related to α- and β-cell dysfunction, insulin sensitivity, and incretin action. A new function describing the influx of glucose from the gut has been introduced. A new rubric for estimating the incretin effect directly from the OGTT experiment has been developed. The effect of glucose dose was also investigated.
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Affiliation(s)
- Vijaya Subramanian
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Jonatan I Bagger
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Clinical Research, Steno Diabetes Center Copenhagen, Herlev, Denmark
| | - Vinayak Harihar
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, United States
- Biophysics Graduate Group, University of California, Berkeley, California, United States
| | - Jens J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip K Knop
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Clinical Research, Steno Diabetes Center Copenhagen, Herlev, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tina Villsbøll
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Clinical Research, Steno Diabetes Center Copenhagen, Herlev, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Shah A, Wondisford FE. Gluconeogenesis Flux in Metabolic Disease. Annu Rev Nutr 2023; 43:153-177. [PMID: 37603427 DOI: 10.1146/annurev-nutr-061121-091507] [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] [Indexed: 08/23/2023]
Abstract
Gluconeogenesis is a critical biosynthetic process that helps maintain whole-body glucose homeostasis and becomes altered in certain medical diseases. We review gluconeogenic flux in various medical diseases, including common metabolic disorders, hormonal imbalances, specific inborn genetic errors, and cancer. We discuss how the altered gluconeogenic activity contributes to disease pathogenesis using data from experiments using isotopic tracer and spectroscopy methodologies. These in vitro, animal, and human studies provide insights into the changes in circulating levels of available gluconeogenesis substrates and the efficiency of converting those substrates to glucose by gluconeogenic organs. We highlight ongoing knowledge gaps, discuss emerging research areas, and suggest future investigations. A better understanding of altered gluconeogenesis flux may ultimately identify novel and targeted treatment strategies for such diseases.
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Affiliation(s)
- Ankit Shah
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA; ,
| | - Fredric E Wondisford
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA; ,
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6
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Yang Z, Cheng J, Shang P, Sun JP, Yu X. Emerging roles of olfactory receptors in glucose metabolism. Trends Cell Biol 2022; 33:463-476. [PMID: 36229334 DOI: 10.1016/j.tcb.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 11/07/2022]
Abstract
Olfactory receptors (ORs) are widely expressed in extra-nasal tissues, where they participate in the regulation of divergent physiological processes. An increasing body of evidence over the past decade has revealed important regulatory roles for extra-nasal ORs in glucose metabolism. Recently, nonodorant endogenous ligands of ORs with metabolic significance have been identified, implying the therapeutic potential of ORs in the treatment of metabolic diseases, such as diabetes and obesity. In this review, we summarize current understanding of the expression patterns and functions of ORs in key tissues involved in glucose metabolism modulation, describe odorant and endogenous OR ligands, explain the biased signaling downstream of ORs, and outline OR therapeutic potential.
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Gastaldelli A. Measuring and estimating insulin resistance in clinical and research settings. Obesity (Silver Spring) 2022; 30:1549-1563. [PMID: 35894085 PMCID: PMC9542105 DOI: 10.1002/oby.23503] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 03/27/2022] [Accepted: 04/21/2022] [Indexed: 11/29/2022]
Abstract
The article discusses how to measure insulin resistance in muscle, liver, and adipose tissue in human participants. The most frequently used methodologies to evaluate insulin resistance are described in detail starting from the gold standard, that is, the euglycemic hyperinsulinemic clamp, to the intravenous glucose tolerance test, surrogate indices based on fasting measurements, or dynamic tests (such as oral glucose or mixed meal tolerance tests). The accuracy, precision, and reproducibility of the tests as well as cutoff values are reported.
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Affiliation(s)
- Amalia Gastaldelli
- National Research Council (CNR)Institute of Clinical Physiology (IFC)PisaItaly
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8
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Quaye E, Chacko S, Chung ST, Brychta RJ, Chen KY, Brown RJ. Energy expenditure due to gluconeogenesis in pathological conditions of insulin resistance. Am J Physiol Endocrinol Metab 2021; 321:E795-E801. [PMID: 34693755 PMCID: PMC8714967 DOI: 10.1152/ajpendo.00281.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Gluconeogenesis (GNG), the formation of glucose from noncarbohydrate precursors, requires adenosine triphosphate (ATP). Previous studies have estimated the energetic cost of GNG in humans based on theoretical calculations of rates of GNG, moles of oxygen consumption by GNG, and average oxygen consumption. Few human studies have measured the energy expenditure (EE) due to GNG. We estimated EE attributable to GNG in patients with three insulin resistance conditions and high GNG rates (insulin receptor pathogenic variants, lipodystrophy, and type 2 diabetes) and obesity without diabetes. Fractional GNG was measured by incorporation of deuterium from body water into newly formed glucose, endogenous glucose production (EGP) as glucose appearance following administration of [6,6-2H2]glucose, and total GNG as fractional GNG × EGP. EE was measured by indirect calorimetry and compared with predicted EE from the Mifflin St. Jeor equation. EE attributable to GNG was estimated using linear regression after accounting for age and fat-free mass (FFM). EE in patients with insulin resistance was significantly higher than predicted by the Mifflin St. Jeor equation. GNG correlated with resting EE (REE). EE attributable to GNG in patients with insulin resistance was almost one-third of REE, substantially higher than theorized in healthy subjects. Our findings demonstrate that GNG is a significant contributor to EE in insulin-resistant states. Prediction equations may underestimate caloric needs in patients with insulin resistance. Therefore, targeting caloric needs to account for higher EE due to increased GNG should be considered in energy balance studies in patients with insulin resistance.NEW & NOTEWORTHY Gluconeogenesis is an energy-requiring process that is upregulated in diabetes, contributing to hyperglycemia. Previous studies have estimated that gluconeogenesis accounts for less than 10% of resting energy expenditure. This study estimates the energy expenditure attributable to gluconeogenesis in uncommon and severe forms of insulin resistance and common, milder forms of insulin resistance. In these populations, gluconeogenesis accounts for almost one-third of resting energy expenditure, substantially higher than previously theorized in the literature.
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Affiliation(s)
- Emmanuel Quaye
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Shaji Chacko
- US Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Stephanie T Chung
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Robert J Brychta
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Kong Y Chen
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Rebecca J Brown
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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9
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The aetiology and molecular landscape of insulin resistance. Nat Rev Mol Cell Biol 2021; 22:751-771. [PMID: 34285405 DOI: 10.1038/s41580-021-00390-6] [Citation(s) in RCA: 192] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2021] [Indexed: 02/07/2023]
Abstract
Insulin resistance, defined as a defect in insulin-mediated control of glucose metabolism in tissues - prominently in muscle, fat and liver - is one of the earliest manifestations of a constellation of human diseases that includes type 2 diabetes and cardiovascular disease. These diseases are typically associated with intertwined metabolic abnormalities, including obesity, hyperinsulinaemia, hyperglycaemia and hyperlipidaemia. Insulin resistance is caused by a combination of genetic and environmental factors. Recent genetic and biochemical studies suggest a key role for adipose tissue in the development of insulin resistance, potentially by releasing lipids and other circulating factors that promote insulin resistance in other organs. These extracellular factors perturb the intracellular concentration of a range of intermediates, including ceramide and other lipids, leading to defects in responsiveness of cells to insulin. Such intermediates may cause insulin resistance by inhibiting one or more of the proximal components in the signalling cascade downstream of insulin (insulin receptor, insulin receptor substrate (IRS) proteins or AKT). However, there is now evidence to support the view that insulin resistance is a heterogeneous disorder that may variably arise in a range of metabolic tissues and that the mechanism for this effect likely involves a unified insulin resistance pathway that affects a distal step in the insulin action pathway that is more closely linked to the terminal biological response. Identifying these targets is of major importance, as it will reveal potential new targets for treatments of diseases associated with insulin resistance.
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Rahman MS, Hossain KS, Das S, Kundu S, Adegoke EO, Rahman MA, Hannan MA, Uddin MJ, Pang MG. Role of Insulin in Health and Disease: An Update. Int J Mol Sci 2021; 22:6403. [PMID: 34203830 PMCID: PMC8232639 DOI: 10.3390/ijms22126403] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/12/2021] [Accepted: 06/14/2021] [Indexed: 02/06/2023] Open
Abstract
Insulin is a polypeptide hormone mainly secreted by β cells in the islets of Langerhans of the pancreas. The hormone potentially coordinates with glucagon to modulate blood glucose levels; insulin acts via an anabolic pathway, while glucagon performs catabolic functions. Insulin regulates glucose levels in the bloodstream and induces glucose storage in the liver, muscles, and adipose tissue, resulting in overall weight gain. The modulation of a wide range of physiological processes by insulin makes its synthesis and levels critical in the onset and progression of several chronic diseases. Although clinical and basic research has made significant progress in understanding the role of insulin in several pathophysiological processes, many aspects of these functions have yet to be elucidated. This review provides an update on insulin secretion and regulation, and its physiological roles and functions in different organs and cells, and implications to overall health. We cast light on recent advances in insulin-signaling targeted therapies, the protective effects of insulin signaling activators against disease, and recommendations and directions for future research.
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Affiliation(s)
- Md Saidur Rahman
- Department of Animal Science & Technology and BET Research Institute, Chung-Ang University, Anseong 17546, Korea; (M.S.R.); (E.O.A.)
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Khandkar Shaharina Hossain
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Sharnali Das
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Sushmita Kundu
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Elikanah Olusayo Adegoke
- Department of Animal Science & Technology and BET Research Institute, Chung-Ang University, Anseong 17546, Korea; (M.S.R.); (E.O.A.)
| | - Md. Ataur Rahman
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
- Department of Pathology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Korea
| | - Md. Abdul Hannan
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
- Department of Biochemistry and Molecular Biology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Md Jamal Uddin
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Woman’s University, Seoul 03760, Korea
| | - Myung-Geol Pang
- Department of Animal Science & Technology and BET Research Institute, Chung-Ang University, Anseong 17546, Korea; (M.S.R.); (E.O.A.)
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11
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Honegger M, Lutz TA, Boyle CN. Hypoglycemia attenuates acute amylin-induced reduction of food intake in male rats. Physiol Behav 2021; 237:113435. [PMID: 33933418 DOI: 10.1016/j.physbeh.2021.113435] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/09/2021] [Accepted: 04/23/2021] [Indexed: 12/17/2022]
Abstract
The ability of amylin to inhibit gastric emptying and glucagon secretion in rats is reduced under hypoglycemic conditions. These effects are considered part of a fail-safe mechanism that prevents amylin from further decreasing nutrient supply when blood glucose levels are low. Because these actions and amylin-induced satiation are mediated by the area postrema (AP), it is plausible that these phenomena are based on the co-sensitivity of AP neurons to amylin and glucose. Using hyperinsulinemic glucose clamps in unrestrained and freely-feeding rats, we investigated whether amylin's ability to inhibit food intake is also reduced by hypoglycemia (HYPO). Following an 18 h fast, rats were infused with insulin and glucose for 45 min to clamp blood glucose at baseline levels (between 90 and 100 mg/dL). HYPO (approximately 55 mg/dL) was induced between 45 and 60 min and then maintained for the remainder of the clamp. Rats were injected with amylin (20 µg/kg) or saline and offered normal chow at 85 min. Food intake was measured at 30 and 60 min after amylin. Control hyperinsulinemic/euglycemic (EU) rats were maintained at approximately 150 mg/dL (which is a physiological periprandial glucose level) before and after amylin injection. Terminal experiments tested the effect of amylin to induce the phosphorylation of ERK, a marker of amylin action in the AP, in EU and HYPO conditions. Amylin significantly reduced 30- and 60-min food intake in EU rats, but the effect at 60-min was attenuated in HYPO rats. Interestingly, glucose infusion rate had to be dramatically reduced at meal onset in saline-treated, but not in amylin-treated, EU or HYPO rats; this suggests that meal-related glucose appearance in the blood was inhibited by amylin under both EU and HYPO. Finally, amylin induced a similar pERK response in the AP in EU and HYPO rats. We conclude that amylin's action to decrease eating is blunted in hypoglycemia, and this effect seems to be downstream from amylin-induced pERK in AP neurons. These data allow us to extend the idea of a hypoglycemic brake on amylin's actions to its food intake-reducing effect, but also demonstrate that amylin can buffer meal-induced glucose appearance at EU and HYPO levels.
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Affiliation(s)
- Miriam Honegger
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), 8057 Zurich, Switzerland
| | - Thomas A Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), 8057 Zurich, Switzerland; Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland
| | - Christina N Boyle
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), 8057 Zurich, Switzerland.
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12
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Ardaiz N, Gomar C, Vasquez M, Tenesaca S, Fernandez-Sendin M, Di Trani CA, Belsué V, Escalada J, Werner U, Tennagels N, Berraondo P. Insulin Fused to Apolipoprotein A-I Reduces Body Weight and Steatosis in DB/DB Mice. Front Pharmacol 2021; 11:591293. [PMID: 33679386 PMCID: PMC7934061 DOI: 10.3389/fphar.2020.591293] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 12/23/2020] [Indexed: 01/06/2023] Open
Abstract
Background: Targeting long-lasting insulins to the liver may improve metabolic alterations that are not corrected with current insulin replacement therapies. However, insulin is only able to promote lipogenesis but not to block gluconeogenesis in the insulin-resistant liver, exacerbating liver steatosis associated with diabetes. Methods: In order to overcome this limitation, we fused a single-chain insulin to apolipoprotein A-I, and we evaluated the pharmacokinetics and pharmacodynamics of this novel fusion protein in wild type mice and in db/db mice using both recombinant proteins and recombinant adenoassociated virus (AAV). Results: Here, we report that the fusion protein between single-chain insulin and apolipoprotein A-I prolonged the insulin half-life in circulation, and accumulated in the liver. We analyzed the long-term effect of these insulin fused to apolipoprotein A-I or insulin fused to albumin using AAVs in the db/db mouse model of diabetes, obesity, and liver steatosis. While AAV encoding insulin fused to albumin exacerbated liver steatosis in several mice, AAV encoding insulin fused to apolipoprotein A-I reduced liver steatosis. These results were confirmed upon daily subcutaneous administration of the recombinant insulin-apolipoprotein A-I fusion protein for six weeks. The reduced liver steatosis was associated with reduced body weight in mice treated with insulin fused to apolipoprotein A-I. Recombinant apolipoprotein A-I alone significantly reduces body weight and liver weight, indicating that the apolipoprotein A-I moiety is the main driver of these effects. Conclusion: The fusion protein of insulin and apolipoprotein A-I could be a promising insulin derivative for the treatment of diabetic patients with associated fatty liver disease.
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Affiliation(s)
- Nuria Ardaiz
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Celia Gomar
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Marcos Vasquez
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Shirley Tenesaca
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Myriam Fernandez-Sendin
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Claudia Augusta Di Trani
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Virginia Belsué
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain
| | - Javier Escalada
- IdiSNA, Navarra Institute for Health Research, Pamplona, Spain.,Department of Endocrinology, Clínica Universidad de Navarra, Pamplona, Spain.,Centro de Investigación Biomédica en Red de la Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Madrid, Spain
| | - Ulrich Werner
- Sanofi-Aventis Deutschland GmbH, TA Diabetes, Frankfurt am Main, Germany
| | - Norbert Tennagels
- Sanofi-Aventis Deutschland GmbH, TA Diabetes, Frankfurt am Main, Germany
| | - Pedro Berraondo
- Program of Immunology and Immunotherapy, Cima Universidad de Navarra, Pamplona, Spain.,IdiSNA, Navarra Institute for Health Research, Pamplona, Spain.,Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain
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13
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Hsu JY, Lin HH, Wang ZH, Chen JH. Aqueous extract from Pepino (Solanum muricatum Ait.) leaves ameliorated insulin resistance, hyperlipidemia, and hyperglycemia in mice with metabolic syndrome. J Food Biochem 2020; 44:e13518. [PMID: 33047354 DOI: 10.1111/jfbc.13518] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/30/2020] [Accepted: 09/24/2020] [Indexed: 12/14/2022]
Abstract
Solanum muricatum Ait. (Pepino) is a plant food commonly cultivated in the Penghu Island, Taiwan. This present study aimed to investigate the protective effects of aqueous extract of Pepino leaves (AEPL) in mice with metabolic syndrome. Metabolic syndrome animal model was induced by continuous high-fat diet feeding and low-dose streptozotocin (40 mg/ml) for 5 days. A 1% AEPL or metformin were given for 6 weeks after streptozotocin injection. The results revealed that 1% AEPL effectively reduced fasting blood glucose, insulin resistance, and hyperlipidemia in metabolic syndrome mice. Histologic examination revealed lipid accumulation in liver decreased by 1% AEPL treatment. Further, western blot analysis revealed 1% AEPL treatment managed enzymes related to lipid synthesis and oxidation pathways and hepatic glucose production. Besides, 1% AEPL treatment increased liver antioxidant activities to against oxidative stress. These results concluded that AEPL treatment attenuated insulin resistance, hyperlipidemia, and hyperglycemia of metabolic syndrome. PRACTICAL APPLICATIONS: Metabolic syndrome (MS) is a multifactorial chronic disease which is characterized by dyslipidemia, insulin resistance, and hyperglycemia. However, there is no single drug or defined medication for MS so far. The present study revealed that AEPL treatment was able to regulate lipid metabolism and glycemic control at the molecular level to alleviate MS. AEPL has the potential to be a novo complementary medication for metabolic syndrome.
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Affiliation(s)
- Jen-Ying Hsu
- Department of Nutrition, Chung Shan Medical University, Taichung City, Taiwan
| | - Hui-Hsuan Lin
- Department of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung City, Taiwan
| | - Zhi-Hong Wang
- Department of Food Nutrition and Health Biotechnology, Asia University, Taichung City, Taiwan
| | - Jing-Hsien Chen
- Department of Nutrition, Chung Shan Medical University, Taichung City, Taiwan.,Department of Medical Research, Chung Shan Medical University Hospital, Taichung City, Taiwan
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14
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Shah AM, Wondisford FE. Tracking the carbons supplying gluconeogenesis. J Biol Chem 2020; 295:14419-14429. [PMID: 32817317 DOI: 10.1074/jbc.rev120.012758] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 08/12/2020] [Indexed: 11/06/2022] Open
Abstract
As the burden of type 2 diabetes mellitus (T2DM) grows in the 21st century, the need to understand glucose metabolism heightens. Increased gluconeogenesis is a major contributor to the hyperglycemia seen in T2DM. Isotope tracer experiments in humans and animals over several decades have offered insights into gluconeogenesis under euglycemic and diabetic conditions. This review focuses on the current understanding of carbon flux in gluconeogenesis, including substrate contribution of various gluconeogenic precursors to glucose production. Alterations of gluconeogenic metabolites and fluxes in T2DM are discussed. We also highlight ongoing knowledge gaps in the literature that require further investigation. A comprehensive analysis of gluconeogenesis may enable a better understanding of T2DM pathophysiology and identification of novel targets for treating hyperglycemia.
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Affiliation(s)
- Ankit M Shah
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
| | - Fredric E Wondisford
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
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15
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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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16
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Glucose transporters in adipose tissue, liver, and skeletal muscle in metabolic health and disease. Pflugers Arch 2020; 472:1273-1298. [PMID: 32591906 PMCID: PMC7462924 DOI: 10.1007/s00424-020-02417-x] [Citation(s) in RCA: 172] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 06/01/2020] [Accepted: 06/05/2020] [Indexed: 12/13/2022]
Abstract
A family of facilitative glucose transporters (GLUTs) is involved in regulating tissue-specific glucose uptake and metabolism in the liver, skeletal muscle, and adipose tissue to ensure homeostatic control of blood glucose levels. Reduced glucose transport activity results in aberrant use of energy substrates and is associated with insulin resistance and type 2 diabetes. It is well established that GLUT2, the main regulator of hepatic hexose flux, and GLUT4, the workhorse in insulin- and contraction-stimulated glucose uptake in skeletal muscle, are critical contributors in the control of whole-body glycemia. However, the molecular mechanism how insulin controls glucose transport across membranes and its relation to impaired glycemic control in type 2 diabetes remains not sufficiently understood. An array of circulating metabolites and hormone-like molecules and potential supplementary glucose transporters play roles in fine-tuning glucose flux between the different organs in response to an altered energy demand.
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17
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Smajis S, Gajdošík M, Pfleger L, Traussnigg S, Kienbacher C, Halilbasic E, Ranzenberger-Haider T, Stangl A, Beiglböck H, Wolf P, Lamp T, Hofer A, Gastaldelli A, Barbieri C, Luger A, Trattnig S, Kautzky-Willer A, Krššák M, Trauner M, Krebs M. Metabolic effects of a prolonged, very-high-dose dietary fructose challenge in healthy subjects. Am J Clin Nutr 2020; 111:369-377. [PMID: 31796953 DOI: 10.1093/ajcn/nqz271] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 10/08/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Increased fructose intake has been associated with metabolic consequences such as impaired hepatic lipid metabolism and development of nonalcoholic fatty liver disease (NAFLD). OBJECTIVES The aim of this study was to investigate the role of fructose in glucose and lipid metabolism in the liver, heart, skeletal muscle, and adipose tissue. METHODS Ten healthy subjects (age: 28 ± 19 y; BMI: 22.2 ± 0.7 kg/m2) underwent comprehensive metabolic phenotyping prior to and 8 wk following a high-fructose diet (150 g daily). Eleven patients with NAFLD (age: 39.4 ± 3.95 y; BMI: 28.4 ± 1.25) were characterized as "positive controls." Insulin sensitivity was analyzed by a 2-step hyperinsulinemic euglycemic clamp, and postprandial interorgan crosstalk of lipid and glucose metabolism was evaluated, by determining postprandial hepatic and intra-myocellular lipid and glycogen accumulation, employing magnetic resonance spectroscopy (MRS) at 7 T. Myocardial lipid content and myocardial function were assessed by 1H MRS imaging and MRI at 3 T. RESULTS High fructose intake resulted in lower intake of other dietary sugars and did not increase total daily energy intake. Ectopic lipid deposition and postprandial glycogen storage in the liver and skeletal muscle were not altered. Postprandial changes in hepatic lipids were measured [Δhepatocellular lipid (HCL)_healthy_baseline: -15.9 ± 10.7 compared with ± ΔHCL_healthy_follow-up: -6.9 ± 4.6; P = 0.17] and hepatic glycogen (Δglycogen_baseline: 64.4 ± 14.1 compared with Δglycogen_follow-up: 51.1 ± 9.8; P = 0.42). Myocardial function and myocardial mass remained stable. As expected, impaired hepatic glycogen storage and increased ectopic lipid storage in the liver and skeletal muscle were observed in insulin-resistant patients with NAFLD. CONCLUSIONS Ingestion of a high dose of fructose for 8 wk was not associated with relevant metabolic consequences in the presence of a stable energy intake, slightly lower body weight, and potentially incomplete absorption of the orally administered fructose load. This indicated that young, metabolically healthy subjects can at least temporarily compensate for increased fructose intake. This trial was registered at www.clinicaltrials.gov as NCT02075164.
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Affiliation(s)
- Sabina Smajis
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
| | - Martin Gajdošík
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria.,High Field MR Center, Department for Biomedical Imaging and Image Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Lorenz Pfleger
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria.,High Field MR Center, Department for Biomedical Imaging and Image Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Stefan Traussnigg
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Christian Kienbacher
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Emina Halilbasic
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | | | - Anna Stangl
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
| | - Hannes Beiglböck
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
| | - Peter Wolf
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
| | - Tanja Lamp
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Astrid Hofer
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
| | | | - Chiara Barbieri
- National Research Council Institute of Clinical Physiology, Pisa, Italy
| | - Anton Luger
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
| | - Siegfried Trattnig
- High Field MR Center, Department for Biomedical Imaging and Image Guided Therapy, Medical University of Vienna, Vienna, Austria
| | | | - Martin Krššák
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria.,High Field MR Center, Department for Biomedical Imaging and Image Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Michael Krebs
- Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna, Austria
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18
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Warner SO, Yao MV, Cason RL, Winnick JJ. Exercise-Induced Improvements to Whole Body Glucose Metabolism in Type 2 Diabetes: The Essential Role of the Liver. Front Endocrinol (Lausanne) 2020; 11:567. [PMID: 32982968 PMCID: PMC7484211 DOI: 10.3389/fendo.2020.00567] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/13/2020] [Indexed: 01/22/2023] Open
Abstract
Type 2 diabetes (T2D) is a metabolic disease characterized by obesity, insulin resistance, and the dysfunction of several key glucoregulatory organs. Among these organs, impaired liver function is recognized as one of the earliest contributors to impaired whole-body glucose homeostasis, with well-characterized hepatic insulin resistance resulting in elevated rates of hepatic glucose production (HGP) and fasting hyperglycemia. One portion of this review will provide an overview of how HGP is regulated during the fasted state in healthy humans and how this process becomes dysregulated in patients with T2D. Less well-appreciated is the liver's role in post-prandial glucose metabolism, where it takes up and metabolizes one-third of orally ingested glucose. An abundance of literature has shown that the process of hepatic glucose uptake is impaired in patients with T2D, thereby contributing to glucose intolerance. A second portion of this review will outline how hepatic glucose uptake is regulated during the post-prandial state, and how it becomes dysfunctional in patients with T2D. Finally, it is well-known that exercise training has an insulin-sensitizing effect on the liver, which contributes to improved whole-body glucose metabolism in patients with T2D, thereby making it a cornerstone in the management of the disease. To this end, the impact of exercise on hepatic glucose metabolism will be thoroughly discussed, referencing key findings in the literature. At the same time, sources of heterogeneity that contribute to inconsistent findings in the field will be pointed out, as will important topics for future investigation.
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Affiliation(s)
- Shana O. Warner
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Michael V. Yao
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Rebecca L. Cason
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Jason J. Winnick
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- *Correspondence: Jason J. Winnick
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19
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Gastaldelli A, Cusi K. From NASH to diabetes and from diabetes to NASH: Mechanisms and treatment options. JHEP Rep 2019; 1:312-328. [PMID: 32039382 PMCID: PMC7001557 DOI: 10.1016/j.jhepr.2019.07.002] [Citation(s) in RCA: 221] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/14/2019] [Accepted: 07/11/2019] [Indexed: 02/06/2023] Open
Abstract
The worldwide prevalence of non-alcoholic fatty liver disease (NAFLD) is estimated to have reached 25% or more in adults. NAFLD is prevalent in obese individuals, but may also affect non-obese insulin-resistant individuals. NAFLD is associated with a 2- to 3-fold increased risk of developing type 2 diabetes (T2D), which may be higher in patients with more severe liver disease - fibrosis increases this risk. In NAFLD, not only the close association with obesity, but also the impairment of many metabolic pathways, including decreased hepatic insulin sensitivity and insulin secretion, increase the risk of developing T2D and related comorbidities. Conversely, patients with diabetes have a higher prevalence of steatohepatitis, liver fibrosis and end-stage liver disease. Genetics and mechanisms involving dysfunctional adipose tissue, lipotoxicity and glucotoxicity appear to play a role. In this review, we discuss the altered pathophysiological mechanisms that underlie the development of T2D in NAFLD and vice versa. Although there is no approved therapy for the treatment of NASH, we discuss pharmacological agents currently available to treat T2D that could potentially be useful for the management of NASH.
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Affiliation(s)
- Amalia Gastaldelli
- Cardiometabolic Risk Unit, Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Kenneth Cusi
- Division of Endocrinology, Diabetes and Metabolism, The University of Florida, and Malcom Randall Veterans Administration Medical Center, Gainesville, Florida
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20
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Tripathy D, Merovci A, Basu R, Abdul-Ghani M, DeFronzo RA. Mild Physiologic Hyperglycemia Induces Hepatic Insulin Resistance in Healthy Normal Glucose-Tolerant Participants. J Clin Endocrinol Metab 2019; 104:2842-2850. [PMID: 30789980 PMCID: PMC6543508 DOI: 10.1210/jc.2018-02304] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 02/15/2019] [Indexed: 02/07/2023]
Abstract
CONTEXT Chronic hyperglycemia worsens skeletal muscle insulin resistance and β-cell function. However, the effect of sustained physiologic hyperglycemia on hepatic insulin sensitivity is not clear. OBJECTIVE To examine the effect of sustained physiologic hyperglycemia (similar to that observed in patients with type 2 diabetes) on endogenous (primarily reflecting hepatic) glucose production (EGP) in healthy individuals. DESIGN Volunteers participated in a three-step hyperinsulinemic (10, 20, 40 mU/m2 per minute) euglycemic clamp before and after a 48-hour glucose infusion to increase plasma glucose concentration by ∼40 mg/dL above baseline. EGP was measured with 3-3H-glucose before and after chronic glucose infusion. PARTICIPANTS Sixteen persons with normal glucose tolerance [eight with and eight without a family history (FH) of diabetes] participated in the study. MAIN OUTCOME MEASURE EGP. RESULTS Basal EGP increased following 48 hours of glucose infusion (from a mean ± SEM of 2.04 ± 0.08 to 3.06 ± 0.29 mg/kgffm⋅ min; P < 0.005). The hepatic insulin resistance index (basal EGP × fasting plasma insulin) markedly increased following glucose infusion (20.1 ± 1.8 to 51.7 ± 6.6; P < 0.005) in both FH+ and FH- subjects. CONCLUSION Sustained physiologic hyperglycemia for as little as 48 hours increased the rate of basal hepatic glucose production and induced hepatic insulin resistance in health persons with normal glucose tolerance, providing evidence for the role of glucotoxicity in the increase in hepatic glucose production in type 2 diabetes.
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Affiliation(s)
- Devjit Tripathy
- Department of Medicine, Diabetes Division, University of Texas Health Science, San Antonio, Texas
- Audie L Murphy Veterans Affairs Hospital, South Texas Veterans Heath Care System, San Antonio, Texas
| | - Aurora Merovci
- Department of Medicine, Diabetes Division, University of Texas Health Science, San Antonio, Texas
| | - Rita Basu
- Department of Medicine, Endocrinology Division, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Muhammad Abdul-Ghani
- Department of Medicine, Diabetes Division, University of Texas Health Science, San Antonio, Texas
| | - Ralph A DeFronzo
- Department of Medicine, Diabetes Division, University of Texas Health Science, San Antonio, Texas
- Audie L Murphy Veterans Affairs Hospital, South Texas Veterans Heath Care System, San Antonio, Texas
- Correspondence and Reprint Requests: Ralph A. DeFronzo, MD, Diabetes Division, University of Texas Health Science, 7703 Floyd Curl Drive, San Antonio, Texas 78229. E-mail:
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21
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NMR-Based Metabolomic Approach Tracks Potential Serum Biomarkers of Disease Progression in Patients with Type 2 Diabetes Mellitus. J Clin Med 2019; 8:jcm8050720. [PMID: 31117294 PMCID: PMC6571571 DOI: 10.3390/jcm8050720] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/10/2019] [Accepted: 05/15/2019] [Indexed: 12/15/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by chronic hyperglycemia associated with alterations in carbohydrate, lipid, and protein metabolism. The prognosis of T2DM patients is highly dependent on the development of complications, and therefore the identification of biomarkers of T2DM progression, with minimally invasive techniques, is a huge need. In the present study, we applied a 1H-Nuclear Magnetic Resonance (1H-NMR)-based metabolomic approach coupled with multivariate data analysis to identify serum metabolite profiles associated with T2DM development and progression. To perform this, we compared the serum metabolome of non-diabetic subjects, treatment-naïve non-complicated T2DM patients, and T2DM patients with complications in insulin monotherapy. Our analysis revealed a significant reduction of alanine, glutamine, glutamate, leucine, lysine, methionine, tyrosine, and phenylalanine in T2DM patients with respect to non-diabetic subjects. Moreover, isoleucine, leucine, lysine, tyrosine, and valine levels distinguished complicated patients from patients without complications. Overall, the metabolic pathway analysis suggested that branched-chain amino acid (BCAA) metabolism is significantly compromised in T2DM patients with complications, while perturbation in the metabolism of gluconeogenic amino acids other than BCAAs characterizes both early and advanced T2DM stages. In conclusion, we identified a metabolic serum signature associated with T2DM stages. These data could be integrated with clinical characteristics to build a composite T2DM/complications risk score to be validated in a prospective cohort.
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Sato T, Watanabe Y, Nishimura Y, Inoue M, Morita A, Miura S. Acute fructose intake suppresses fasting-induced hepatic gluconeogenesis through the AKT-FoxO1 pathway. Biochem Biophys Rep 2019; 18:100638. [PMID: 31032430 PMCID: PMC6479072 DOI: 10.1016/j.bbrep.2019.100638] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/19/2019] [Accepted: 04/08/2019] [Indexed: 11/21/2022] Open
Abstract
Excessive intake of fructose increases lipogenesis in the liver, leading to hepatic lipid accumulation and development of fatty liver disease. Metabolic alterations in the liver due to fructose intake have been reported in many studies, but the effect of fructose administration on hepatic gluconeogenesis is not fully understood. The aim of this study was to evaluate the acute effects of fructose administration on fasting-induced hepatic gluconeogenesis. C57BL/6J mice were administered fructose solution after 14 h of fasting and plasma insulin, glucose, free fatty acids, and ketone bodies were analysed. We also measured phosphorylated AKT and forkhead box O (FoxO) 1 protein levels and gene expression related to gluconeogenesis in the liver. Furthermore, we measured glucose production from pyruvate after fructose administration. Glucose-administered mice were used as controls. Fructose administration enhanced phosphorylation of AKT in the liver, without increase of blood insulin levels. Blood free fatty acids and ketone bodies concentrations were as high as those in the fasting group after fructose administration, suggesting that insulin-induced inhibition of lipolysis did not occur in mice administered with fructose. Fructose also enhanced phosphorylation of FoxO1 and suppressed gluconeogenic gene expression, glucose-6-phosphatase activity, and glucose production from pyruvate. The present study suggests that acute fructose administration suppresses fasting-induced hepatic gluconeogenesis in an insulin-independent manner. Fructose administration does not increase blood glucose and insulin levels. Fructose administration suppressed fasting-induced hepatic gluconeogenic gene expression and G6Pase activity. Fructose accelerates FoxO1 phosphorylation through the AKT-FoxO1 pathway. We propose that fructose intake suppresses fasting-induced hepatic gluconeogenesis in an insulin-independent manner.
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Key Words
- AKT
- CREB, cAMP response element binding protein
- ChREBP, carbohydrate response element binding protein
- EDTA, ethylenediaminetetraacetic acid
- FFA, free fatty acid
- FoxO, forkhead box O
- FoxO1
- Fructose
- G6Pase
- G6Pase, glucose-6-phosphatase
- Gluconeogenesis
- Insulin
- PEPCK, phosphoenolpyruvate carboxykinase
- PGC-1α, peroxisome proliferator-activated receptor gamma coactivator-1 alpha
- PI3K, phosphoinositide-3-kinase
- PIP 3, phosphatidylinositol-(3,4,5)-trisphosphate
- SREBP, sterol-regulatory element binding protein
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Affiliation(s)
- Tomoki Sato
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.,Research Fellow of Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan
| | - Yui Watanabe
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Yuri Nishimura
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Mizuki Inoue
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Akihito Morita
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Shinji Miura
- Laboratory of Nutritional Biochemistry, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
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Kaur R, Dahiya L, Kumar M. Fructose-1,6-bisphosphatase inhibitors: A new valid approach for management of type 2 diabetes mellitus. Eur J Med Chem 2017; 141:473-505. [DOI: 10.1016/j.ejmech.2017.09.029] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/14/2017] [Accepted: 09/16/2017] [Indexed: 11/27/2022]
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24
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3-(2-amino-ethyl)-5-[3-(4-butoxyl-phenyl)-propylidene]-thiazolidine-2,4-dione (K145) ameliorated dexamethasone induced hepatic gluconeogenesis through activation of Akt/FoxO1 pathway. Biochem Biophys Res Commun 2017; 493:286-290. [DOI: 10.1016/j.bbrc.2017.09.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/06/2017] [Indexed: 11/22/2022]
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25
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Hatting M, Tavares CDJ, Sharabi K, Rines AK, Puigserver P. Insulin regulation of gluconeogenesis. Ann N Y Acad Sci 2017; 1411:21-35. [PMID: 28868790 DOI: 10.1111/nyas.13435] [Citation(s) in RCA: 284] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/16/2017] [Accepted: 06/26/2017] [Indexed: 12/11/2022]
Abstract
The coordinated regulation between cellular glucose uptake and endogenous glucose production is indispensable for the maintenance of constant blood glucose concentrations. The liver contributes significantly to this process by altering the levels of hepatic glucose release, through controlling the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis). Various nutritional and hormonal stimuli signal to alter hepatic gluconeogenic flux, and suppression of this metabolic pathway during the postprandial state can, to a significant extent, be attributed to insulin. Here, we review some of the molecular mechanisms through which insulin modulates hepatic gluconeogenesis, thus controlling glucose production by the liver to ultimately maintain normoglycemia. Various signaling pathways governed by insulin converge at the level of transcriptional regulation of the key hepatic gluconeogenic genes PCK1 and G6PC, highlighting this as one of the focal mechanisms through which gluconeogenesis is modulated. In individuals with compromised insulin signaling, such as insulin resistance in type 2 diabetes, insulin fails to suppress hepatic gluconeogenesis, even in the fed state; hence, an insight into these insulin-moderated pathways is critical for therapeutic purposes.
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Affiliation(s)
- Maximilian Hatting
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Clint D J Tavares
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Kfir Sharabi
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Amy K Rines
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
| | - Pere Puigserver
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts
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26
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Miller C, Pachanski MJ, Kirkland ME, Kosinski DT, Mane J, Bunzel M, Cao J, Souza S, Thomas-Fowlkes B, Di Salvo J, Weinglass AB, Li X, Myers RW, Knagge K, Carrington PE, Hagmann WK, Trujillo ME. GPR40 partial agonist MK-2305 lower fasting glucose in the Goto Kakizaki rat via suppression of endogenous glucose production. PLoS One 2017; 12:e0176182. [PMID: 28542610 PMCID: PMC5441580 DOI: 10.1371/journal.pone.0176182] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/06/2017] [Indexed: 11/19/2022] Open
Abstract
GPR40 (FFA1) is a fatty acid receptor whose activation results in potent glucose lowering and insulinotropic effects in vivo. Several reports illustrate that GPR40 agonists exert glucose lowering in diabetic humans. To assess the mechanisms by which GPR40 partial agonists improve glucose homeostasis, we evaluated the effects of MK-2305, a potent and selective partial GPR40 agonist, in diabetic Goto Kakizaki rats. MK-2305 decreased fasting glucose after acute and chronic treatment. MK-2305-mediated changes in glucose were coupled with increases in plasma insulin during hyperglycemia and glucose challenges but not during fasting, when glucose was normalized. To determine the mechanism(s) mediating these changes in glucose metabolism, we measured the absolute contribution of precursors to glucose production in the presence or absence of MK-2305. MK-2305 treatment resulted in decreased endogenous glucose production (EGP) driven primarily through changes in gluconeogenesis from substrates entering at the TCA cycle. The decrease in EGP was not likely due to a direct effect on the liver, as isolated perfused liver studies showed no effect of MK-2305 ex vivo and GPR40 is not expressed in the liver. Taken together, our results suggest MK-2305 treatment increases glucose stimulated insulin secretion (GSIS), resulting in changes to hepatic substrate handling that improve glucose homeostasis in the diabetic state. Importantly, these data extend our understanding of the underlying mechanisms by which GPR40 partial agonists reduce hyperglycemia.
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Affiliation(s)
- Corin Miller
- Departments of Translational Imaging Biomarkers, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Michele J. Pachanski
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Melissa E. Kirkland
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Daniel T. Kosinski
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Joel Mane
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Michelle Bunzel
- Departments of Translational Imaging Biomarkers, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Jin Cao
- Departments of Translational Imaging Biomarkers, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Sarah Souza
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Brande Thomas-Fowlkes
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Jerry Di Salvo
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Adam B. Weinglass
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Xiaoyan Li
- Cardio-Metabolic Diseases, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Robert W. Myers
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Kevin Knagge
- David H Murdock Research Institute, Kannapolis, North Carolina, United States of America
| | - Paul E. Carrington
- Cardio-Metabolic Diseases, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - William K. Hagmann
- Chemistry, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Maria E. Trujillo
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
- * E-mail:
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27
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Kuang JR, Zhang ZH, Leng WL, Lei XT, Liang ZW. Dapper1 attenuates hepatic gluconeogenesis and lipogenesis by activating PI3K/Akt signaling. Mol Cell Endocrinol 2017; 447:106-115. [PMID: 28237722 DOI: 10.1016/j.mce.2017.02.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 02/15/2017] [Accepted: 02/16/2017] [Indexed: 01/01/2023]
Abstract
Studies have shown that hepatic insulin resistance, a disorder of glucose and lipid metabolism, plays a vital role in type 2 diabetes (T2D). To clarify the function of Dapper1 in glucose and lipid metabolism in the liver, we investigated the relationships between Dapper1 and adenosine triphosphate (ATP)- and Ca2+-mediated activation of PI3K/Akt. We observed a reduction in hepatic Dapper1 in db/db (mice that are homozygous for a spontaneous diabetes mutation) and HFD-induced diabetic mice with T2D. Hepatic overexpression of Dapper1 improved hyperglycemia, insulin resistance, and fatty liver. It also increased Akt (pAkt) signaling and repressed both gluconeogenesis and lipogenesis. Conversely, Ad-shDapper1-induced knockdown of hepatic Dapper1 promoted gluconeogenesis and lipogenesis. Furthermore, Dapper1 activated PI3K p110α/Akt in an insulin-independent manner by inducing ATP production and secretion in vitro. Blockade of P2 ATP receptors, the downstream phospholipase C (PLC), or the inositol triphosphate receptor (IP3R all reduced the Dapper1-induced increase in cytosolic free calcium and Dapper1-mediated PI3K/Akt activation, as did removal of calcium in the medium. In conclusion, Dapper1 attenuates hepatic gluconeogenesis and lipogenesis in T2D.
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Affiliation(s)
- Jian-Ren Kuang
- Department of Endocrinology, The First Affiliated Hospital of Third Military Medical University, Chongqing 400038, China
| | - Zhi-Hui Zhang
- Department of Cardiovascular, The First Affiliated Hospital of Third Military Medical University, Chongqing 400038, China
| | - Wei-Ling Leng
- Department of Endocrinology, The First Affiliated Hospital of Third Military Medical University, Chongqing 400038, China
| | - Xiao-Tian Lei
- Department of Endocrinology, The First Affiliated Hospital of Third Military Medical University, Chongqing 400038, China
| | - Zi-Wen Liang
- Department of Endocrinology, The First Affiliated Hospital of Third Military Medical University, Chongqing 400038, China.
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28
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Bond ST, Howlett KF, Kowalski GM, Mason S, Connor T, Cooper A, Streltsov V, Bruce CR, Walder KR, McGee SL. Lysine post-translational modification of glyceraldehyde-3-phosphate dehydrogenase regulates hepatic and systemic metabolism. FASEB J 2017; 31:2592-2602. [PMID: 28258188 DOI: 10.1096/fj.201601215r] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 02/13/2017] [Indexed: 12/31/2022]
Abstract
Reciprocal regulation of hepatic glycolysis and gluconeogenesis contributes to systemic metabolic homeostasis. Recent evidence from lower order organisms has found that reversible post-translational modification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), particularly acetylation, contributes to the reciprocal regulation of glycolysis/gluconeogenesis. However, whether this occurs in mammalian hepatocytes in vitro or in vivo is unknown. Several proteomics studies have identified 4 lysine residues in critical regions of mammalian GAPDH that are altered by multiple post-translational modifications. In FAO hepatoma cells, mutation of all 4 lysine residues (4K-R GAPDH) to mimic their unmodified state reduced GAPDH glycolytic activity and glycolytic flux and increased gluconeogenic GAPDH activity and glucose production. Hepatic expression of 4K-R GAPDH in mice increased GAPDH gluconeogenic activity and the contribution of gluconeogenesis to endogenous glucose production in the unfed state. Consistent with the increased reliance on the energy-consuming gluconeogenic pathway, plasma free fatty acids and ketones were elevated in mice expressing 4K-R GAPDH, suggesting enhanced lipolysis and hepatic fatty acid oxidation. In normal mice, food withholding and refeeding, as well as hormonal regulators of reciprocal glycolysis/gluconeogenesis, such as insulin, glucagon, and norepinephrine, had no effect on global GAPDH acetylation. However, GAPDH acetylation was reduced in obese and type 2 diabetic db/db mice. These findings show that post-translational modification of GAPDH lysine residues regulates hepatic and systemic metabolism, revealing an unappreciated role for hepatic GAPDH in substrate selection and utilization.-Bond, S. T., Howlett, K. F., Kowalski, G. M., Mason, S., Connor, T., Cooper, A., Streltsov, V., Bruce, C. R., Walder, K. R., McGee, S. L. Lysine post-translational modification of glyceraldehyde-3-phosphate dehydrogenase regulates hepatic and systemic metabolism.
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Affiliation(s)
- Simon T Bond
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia.,Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria, Australia
| | - Kirsten F Howlett
- School of Exercise and Nutrition Sciences, Deakin University, Burwood, New South Wales, Australia.,Institute of Physical Activity and Nutrition, Deakin University, Burwood, New South Wales, Australia
| | - Greg M Kowalski
- School of Exercise and Nutrition Sciences, Deakin University, Burwood, New South Wales, Australia.,Institute of Physical Activity and Nutrition, Deakin University, Burwood, New South Wales, Australia
| | - Shaun Mason
- School of Exercise and Nutrition Sciences, Deakin University, Burwood, New South Wales, Australia.,Institute of Physical Activity and Nutrition, Deakin University, Burwood, New South Wales, Australia
| | - Timothy Connor
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia.,Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria, Australia
| | - Adrian Cooper
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia.,Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria, Australia
| | - Victor Streltsov
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Manufacturing Flagship, Parkville, Victoria, Australia
| | - Clinton R Bruce
- School of Exercise and Nutrition Sciences, Deakin University, Burwood, New South Wales, Australia.,Institute of Physical Activity and Nutrition, Deakin University, Burwood, New South Wales, Australia
| | - Ken R Walder
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia.,Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria, Australia
| | - Sean L McGee
- Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Victoria, Australia; .,Centre for Molecular and Medical Research, Deakin University, Geelong, Victoria, Australia
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Abstract
Gluconeogenesis is a complex metabolic process that involves multiple enzymatic steps regulated by myriad factors, including substrate concentrations, the redox state, activation and inhibition of specific enzyme steps, and hormonal modulation. At present, the most widely accepted technique to determine gluconeogenesis is by measuring the incorporation of deuterium from the body water pool into newly formed glucose. However, several techniques using radioactive and stable-labeled isotopes have been used to quantitate the contribution and regulation of gluconeogenesis in humans. Each method has its advantages, methodological assumptions, and set of propagated errors. In this review, we examine the strengths and weaknesses of the most commonly used stable isotopes methods to measure gluconeogenesis in vivo. We discuss the advantages and limitations of each method and summarize the applicability of these measurements in understanding normal and pathophysiological conditions.
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Affiliation(s)
- Stephanie T Chung
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Shaji K Chacko
- U.S. Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Agneta L Sunehag
- U.S. Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | - Morey W Haymond
- U.S. Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
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30
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Sharabi K, Tavares CDJ, Rines AK, Puigserver P. Molecular pathophysiology of hepatic glucose production. Mol Aspects Med 2015; 46:21-33. [PMID: 26549348 DOI: 10.1016/j.mam.2015.09.003] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 09/09/2015] [Indexed: 12/23/2022]
Abstract
Maintaining blood glucose concentration within a relatively narrow range through periods of fasting or excess nutrient availability is essential to the survival of the organism. This is achieved through an intricate balance between glucose uptake and endogenous glucose production to maintain constant glucose concentrations. The liver plays a major role in maintaining normal whole body glucose levels by regulating the processes of de novo glucose production (gluconeogenesis) and glycogen breakdown (glycogenolysis), thus controlling the levels of hepatic glucose release. Aberrant regulation of hepatic glucose production (HGP) can result in deleterious clinical outcomes, and excessive HGP is a major contributor to the hyperglycemia observed in Type 2 diabetes mellitus (T2DM). Indeed, adjusting glycemia as close as possible to a non-diabetic range is the foremost objective in the medical treatment of patients with T2DM and is currently achieved in the clinic primarily through suppression of HGP. Here, we review the molecular mechanisms controlling HGP in response to nutritional and hormonal signals and discuss how these signals are altered in T2DM.
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Affiliation(s)
- Kfir Sharabi
- Department of Cancer Biology, Department of Cell Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Clint D J Tavares
- Department of Cancer Biology, Department of Cell Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Amy K Rines
- Department of Cancer Biology, Department of Cell Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Pere Puigserver
- Department of Cancer Biology, Department of Cell Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
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31
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Chung ST, Hsia DS, Chacko SK, Rodriguez LM, Haymond MW. Increased gluconeogenesis in youth with newly diagnosed type 2 diabetes. Diabetologia 2015; 58:596-603. [PMID: 25447079 PMCID: PMC4323952 DOI: 10.1007/s00125-014-3455-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/03/2014] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS The role of increased gluconeogenesis as an important contributor to fasting hyperglycaemia at diabetes onset is not known. We evaluated the contribution of gluconeogenesis and glycogenolysis to fasting hyperglycaemia in newly diagnosed youths with type 2 diabetes following an overnight fast. METHODS Basal rates (μmol kg(FFM) (-1) min(-1)) of gluconeogenesis ((2)H2O), glycogenolysis and glycerol production ([(2)H5] glycerol) were measured in 18 adolescents (nine treatment naive diabetic and nine normal-glucose-tolerant obese adolescents). RESULTS Type 2 diabetes was associated with higher gluconeogenesis (9.2 ± 0.6 vs 7.0 ± 0.3 μmol kg(FFM) (-1) min(-1), p < 0.01), plasma fasting glucose (7.0 ± 0.6 vs 5.0 ± 0.2 mmol/l, p = 0.004) and insulin (300 ± 30 vs 126 ± 31 pmol/l, p = 0.001). Glucose production and glycogenolysis were similar between the groups (15.4 ± 0.3 vs 12.4 ± 1.4 μmol kg(FFM) (-1) min(-1), p = 0.06; and 6.2 ± 0.8 vs 5.3 ± 0.7 μmol kg(FFM) (-1) min(-1), p = 0.5, respectively). After controlling for differences in adiposity, gluconeogenesis, glycogenolysis and glucose production were higher in diabetic youth (p ≤ 0.02). Glycerol concentration (84 ± 6 vs 57 ± 6 μmol/l, p = 0.01) and glycerol production (5.0 ± 0.3 vs 3.6 ± 0.5 μmol kg(FFM) (-1) min(-1), p = 0.03) were 40% higher in youth with diabetes. The increased glycerol production could account for only ~1/3 of substrate needed for the increased gluconeogenesis in diabetic youth. CONCLUSION/INTERPRETATIONS Increased gluconeogenesis was a major contributor to fasting hyperglycaemia and hepatic insulin resistance in newly diagnosed untreated adolescents and was an early pathological feature of type 2 diabetes. Increased glycerol availability may represent a significant source of new carbon substrates for increased gluconeogenesis but would not account for all the carbons required to sustain the increased rates.
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Affiliation(s)
- Stephanie T Chung
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH 10 Center Dr. Bld 10-CRC, RM 5-5740, MSC 1612, Bethesda, MD, 20892-1612, USA,
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32
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Wang B, Ding Z, Wang W, Hwang J, Liao YH, Ivy JL. The effect of an amino acid beverage on glucose response and glycogen replenishment after strenuous exercise. Eur J Appl Physiol 2015; 115:1283-94. [PMID: 25600772 DOI: 10.1007/s00421-015-3098-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 12/31/2014] [Indexed: 11/26/2022]
Abstract
PURPOSE We previously reported that an amino acid mixture (AA) was able to lower the glucose response to an oral glucose challenge in both rats and humans. Increased glucose uptake and glycogen storage in muscle might be associated with the faster blood glucose clearance. We therefore tested the effect of two different doses of AA provided with a carbohydrate supplement on blood glucose homeostasis and muscle glycogen replenishment in human subjects after strenuous aerobic exercise. METHODS Ten subjects received a carbohydrate (1.2 g/kg body weight, CHO), CHO/HAA (CHO + 13 g AA), or CHO/LAA (CHO + 6.5 g AA) supplement immediately and 2 h after an intense cycling bout. Muscle biopsies were performed immediately and 4 h after exercise. RESULTS The glucose responses for CHO/HAA and CHO/LAA during recovery were significantly lower than CHO, as was the glucose area under the curve (CHO/HAA 1259.9 ± 27.7, CHO/LAA 1251.5 ± 47.7, CHO 1376.8 ± 52.9 mmol/L 4 h, p < 0.05). Glycogen storage rate was significantly lower in CHO/HAA compared with CHO, while it did not differ significantly between CHO/LAA or CHO (CHO/HAA 15.4 ± 2.0, CHO/LAA 18.1 ± 2.0, CHO 21.5 ± 1.4 µmol/g wet muscle 4 h). CHO/HAA caused a significantly higher insulin response and a greater effect on mTOR and Akt/PKB phosphorylation compared with CHO. Phosphorylation of AS160 and glycogen synthase did not differ across treatments. Likewise, there were no differences in blood lactate across treatments. CONCLUSIONS The AA lowered the glucose response to a carbohydrate supplement after strenuous exercise. However, it was not effective in facilitating subsequent muscle glycogen storage.
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Affiliation(s)
- Bei Wang
- Department of Kinesiology and Health Education, Exercise Physiology and Metabolism Laboratory, University of Texas at Austin, Austin, TX, USA,
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33
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Haeusler RA, Camastra S, Astiarraga B, Nannipieri M, Anselmino M, Ferrannini E. Decreased expression of hepatic glucokinase in type 2 diabetes. Mol Metab 2014; 4:222-6. [PMID: 25737948 PMCID: PMC4338311 DOI: 10.1016/j.molmet.2014.12.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 12/10/2014] [Accepted: 12/12/2014] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND/OBJECTIVES Increased endogenous glucose production is a hallmark of type 2 diabetes. Evidence from animal models has suggested that a likely cause of this is increased mRNA expression of glucose 6-phosphatase and phosphoenolpyruvate carboxykinase (encoded by G6PC, PCK1 and PCK2). But another contributing factor may be decreased liver glucokinase (encoded by GCK). METHODS We examined expression of these enzymes in liver biopsies from 12 nondiabetic and 28 diabetic individuals. Diabetic patients were further separated into those with HbA1c lower or higher than 7.0. RESULTS In diabetic subjects with HbA1c > 7.0, we found that gluconeogenic enzymes were expressed normally, but GCK was suppressed more than 60%. Moreover, HbA1c and fasting glucose were negatively correlated with GCK, but showed no correlation with G6PC, PCK1, or PCK2. CONCLUSION These findings suggest an underlying dysregulation of hepatic GCK expression during frank diabetes, which has implications for the therapeutic use of glucokinase activators in this population.
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Affiliation(s)
- Rebecca A. Haeusler
- Columbia University, Department of Pathology and Cell Biology, New York, NY, USA
- Corresponding author.
| | - Stefania Camastra
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Brenno Astiarraga
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Monica Nannipieri
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
| | - Marco Anselmino
- Division of Bariatric Surgery, Santa Chiara Hospital, Pisa, Italy
| | - Ele Ferrannini
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
- CNR Institute of Clinical Physiology, Italy
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Kowalski GM, Bruce CR. The regulation of glucose metabolism: implications and considerations for the assessment of glucose homeostasis in rodents. Am J Physiol Endocrinol Metab 2014; 307:E859-71. [PMID: 25205823 DOI: 10.1152/ajpendo.00165.2014] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The incidence of insulin resistance and type 2 diabetes (T2D) is increasing at alarming rates. In the quest to understand the underlying causes of and to identify novel therapeutic targets to treat T2D, scientists have become increasingly reliant on the use of rodent models. Here, we provide a discussion on the regulation of rodent glucose metabolism, highlighting key differences and similarities that exist between rodents and humans. In addition, some of the issues and considerations associated with assessing glucose homeostasis and insulin action are outlined. We also discuss the role of the liver vs. skeletal muscle in regulating whole body glucose metabolism in rodents, emphasizing the importance of defective hepatic glucose metabolism in the development of impaired glucose tolerance, insulin resistance, and T2D.
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Affiliation(s)
- Greg M Kowalski
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
| | - Clinton R Bruce
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
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Palmnäs MSA, Cowan TE, Bomhof MR, Su J, Reimer RA, Vogel HJ, Hittel DS, Shearer J. Low-dose aspartame consumption differentially affects gut microbiota-host metabolic interactions in the diet-induced obese rat. PLoS One 2014; 9:e109841. [PMID: 25313461 PMCID: PMC4197030 DOI: 10.1371/journal.pone.0109841] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/28/2014] [Indexed: 12/21/2022] Open
Abstract
Aspartame consumption is implicated in the development of obesity and metabolic disease despite the intention of limiting caloric intake. The mechanisms responsible for this association remain unclear, but may involve circulating metabolites and the gut microbiota. Aims were to examine the impact of chronic low-dose aspartame consumption on anthropometric, metabolic and microbial parameters in a diet-induced obese model. Male Sprague-Dawley rats were randomized into a standard chow diet (CH, 12% kcal fat) or high fat (HF, 60% kcal fat) and further into ad libitum water control (W) or low-dose aspartame (A, 5-7 mg/kg/d in drinking water) treatments for 8 week (n = 10-12 animals/treatment). Animals on aspartame consumed fewer calories, gained less weight and had a more favorable body composition when challenged with HF compared to animals consuming water. Despite this, aspartame elevated fasting glucose levels and an insulin tolerance test showed aspartame to impair insulin-stimulated glucose disposal in both CH and HF, independently of body composition. Fecal analysis of gut bacterial composition showed aspartame to increase total bacteria, the abundance of Enterobacteriaceae and Clostridium leptum. An interaction between HF and aspartame was also observed for Roseburia ssp wherein HF-A was higher than HF-W (P<0.05). Within HF, aspartame attenuated the typical HF-induced increase in the Firmicutes:Bacteroidetes ratio. Serum metabolomics analysis revealed aspartame to be rapidly metabolized and to be associated with elevations in the short chain fatty acid propionate, a bacterial end product and highly gluconeogenic substrate, potentially explaining its negative affects on insulin tolerance. How aspartame influences gut microbial composition and the implications of these changes on the development of metabolic disease require further investigation.
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Affiliation(s)
- Marie S. A. Palmnäs
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Theresa E. Cowan
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Marc R. Bomhof
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Juliet Su
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Raylene A. Reimer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Hans J. Vogel
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Dustin S. Hittel
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jane Shearer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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De Minicis S, Agostinelli L, Rychlicki C, Sorice GP, Saccomanno S, Candelaresi C, Giaccari A, Trozzi L, Pierantonelli I, Mingarelli E, Marzioni M, Muscogiuri G, Gaggini M, Benedetti A, Gastaldelli A, Guido M, Svegliati-Baroni G. HCC development is associated to peripheral insulin resistance in a mouse model of NASH. PLoS One 2014; 9:e97136. [PMID: 24853141 PMCID: PMC4031080 DOI: 10.1371/journal.pone.0097136] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 04/15/2014] [Indexed: 01/10/2023] Open
Abstract
NAFLD is the most common liver disease worldwide but it is the potential evolution to NASH and eventually to hepatocellular carcinoma (HCC), even in the absence of cirrhosis, that makes NAFLD of such clinical importance. Aim: we aimed to create a mouse model reproducing the pathological spectrum of NAFLD and to investigate the role of possible co-factors in promoting HCC. Methods: mice were treated with a choline-deficient L-amino-acid-defined-diet (CDAA) or its control (CSAA diet) and subjected to a low-dose i.p. injection of CCl4 or vehicle. Insulin resistance was measured by the euglycemic-hyperinsulinemic clamp method. Steatosis, fibrosis and HCC were evaluated by histological and molecular analysis. Results: CDAA-treated mice showed peripheral insulin resistance at 1 month. At 1–3 months, extensive steatosis and fibrosis were observed in CDAA and CDAA+CCl4 groups. At 6 months, equal increase in steatosis and fibrosis was observed between the two groups, together with the appearance of tumor. At 9 months of treatment, the 100% of CDAA+CCl4 treated mice revealed tumor versus 40% of CDAA mice. Insulin-like Growth Factor-2 (IGF-2) and Osteopontin (SPP-1) were increased in CDAA mice versus CSAA. Furthermore, Immunostaining for p-AKT, p-c-Myc and Glypican-3 revealed increased positivity in the tumors. Conclusions: the CDAA model promotes the development of HCC from NAFLD-NASH in the presence of insulin resistance but in the absence of cirrhosis. Since this condition is increasingly recognized in humans, our study provides a model that may help understanding mechanisms of carcinogenesis in NAFLD.
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Affiliation(s)
- Samuele De Minicis
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
- * E-mail: (GS-B); (SDM)
| | - Laura Agostinelli
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Chiara Rychlicki
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Gian Pio Sorice
- Università Cattolica del Sacro Cuore, Policlinico Gemelli, Division of Endocrinology and Metabolic Disease, Rome, Italy
- Diabetic Care Clinics, ACISMOM, Rome, Italy
| | - Stefania Saccomanno
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Cinzia Candelaresi
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Andrea Giaccari
- Università Cattolica del Sacro Cuore, Policlinico Gemelli, Division of Endocrinology and Metabolic Disease, Rome, Italy
- Don Gnocchi Foundation Onlus, Milan, Italy
| | - Luciano Trozzi
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Irene Pierantonelli
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Eleonora Mingarelli
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Marco Marzioni
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Giovanna Muscogiuri
- Università Cattolica del Sacro Cuore, Policlinico Gemelli, Division of Endocrinology and Metabolic Disease, Rome, Italy
| | - Melania Gaggini
- Institute of Clinical Physiology, Head of Cardiometabolic Risk Unit, Pisa, Italy
| | - Antonio Benedetti
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
| | - Amalia Gastaldelli
- Institute of Clinical Physiology, Head of Cardiometabolic Risk Unit, Pisa, Italy
| | - Maria Guido
- Università di Padova, Department of Medicine Anatomic Pathology Unit, Padova, Italy
| | - Gianluca Svegliati-Baroni
- Università Politecnica delle Marche, Department of Gastroenterology, Ancona, Italy
- Università Politecnica delle Marche, Obesity Center, Ancona, Italy
- * E-mail: (GS-B); (SDM)
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GdCl3 reduces hyperglycaemia through Akt/FoxO1-induced suppression of hepatic gluconeogenesis in Type 2 diabetic mice. Clin Sci (Lond) 2014; 127:91-100. [DOI: 10.1042/cs20130670] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In the present study, we demonstrate that GdCl3 reduces hyperglycaemia via the Akt/FoxO1-induced suppression of hepatic gluconeogenesis, both in Type 2 diabetic mice (in vivo) and in hepatocarcinoma cells (in vitro), suggesting that GdCl3 may be a potential therapeutic target for diabetes.
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Garg SK, Brazg RL, Bailey TS, Buckingham BA, Slover RH, Klonoff DC, Shin J, Welsh JB, Kaufman FR. Hypoglycemia begets hypoglycemia: the order effect in the ASPIRE in-clinic study. Diabetes Technol Ther 2014; 16:125-30. [PMID: 24405492 DOI: 10.1089/dia.2013.0219] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND The ASPIRE in-clinic study established that automatic suspension of insulin with the threshold suspend (TS) feature reduces the duration of induced hypoglycemia. The study's crossover design allowed the effects of antecedent hypoglycemia to be studied. SUBJECTS AND METHODS The study enrolled 50 subjects who exercised until plasma glucose (YSI glucose and lactate analyzer; YSI, Inc., Yellow Springs, OH) reached ≤85 mg/dL. Hypoglycemia was evaluated after the YSI value reached <70 mg/dL. In TS experiments, insulin was stopped for 2 h once a sensor glucose (SG) value of ≤70 mg/dL was detected; in control experiments, basal insulin delivery continued. Subjects were randomly assigned to Group A (TS in Period 1; control in Period 2) or Group B (control in Period 1; TS in Period 2). Experiments were separated by 3-10 days. RESULTS Hypoglycemia was 63.7 min shorter in Period 1 TS experiments (no preceding control experiment) than in Period 2 TS experiments (one or more preceding control experiment(s)) (P<0.01). The number of experiments prior to a successful TS experiment was lower for Period 1 than for Period 2 (0.36 ± 0.64 vs. 1.57 ± 0.84; P<0.001), as was the cumulative duration of antecedent hypoglycemia (16.6 min vs. 204.6 min; P<0.001). The between-groups difference in hypoglycemia duration was not attributable to differences in SG rates of change, the duration of exercise, or area under the curve of <70 mg/dL × min in the 2 days before the successful experiment (all P>0.3). CONCLUSIONS The TS feature's ability to mitigate hypoglycemia was decreased by an episode or episodes of prolonged antecedent hypoglycemia, suggesting hypoglycemia begets hypoglycemia. The effect of antecedent hypoglycemia should be taken into consideration in the design of future experiments assessing strategies to reduce hypoglycemia.
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Rajpal A, Dube S, Carvalho F, Simoes AR, Figueiredo A, Basu A, Jones J, Basu R. Effects of transaldolase exchange on estimates of gluconeogenesis in type 2 diabetes. Am J Physiol Endocrinol Metab 2013; 305:E465-74. [PMID: 23736541 PMCID: PMC3891223 DOI: 10.1152/ajpendo.00245.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transaldolase (TA) exchange overestimates gluconeogenesis measured with deuterated water (²H₂O). However, it is unknown whether TA differs in people with type 2 diabetes (T2DM). ²H₂O was ingested, and [1-¹³C]acetate and [3-³H]glucose were infused in T2DM (n = 10) and healthy nondiabetic (ND; n = 8) subjects. TA was assessed from the ratio of ¹³C3 to ¹³C4 glucose enrichment (¹³C3/¹³C4) measured by ¹³C NMR. Glucose turnover was measured before (~16-h fast) and during hyperglycemic (~10 mM) moderate-dose insulin (~0.35 mU·kg⁻¹·min⁻¹) clamp. ¹³C3/¹³C4 in T2DM vs. ND was <1.0 and not different at baseline and clamp, indicating equivalent TA. To determine whether incomplete triose phosphate isomerase (TPI) exchange contributed to asymmetric ¹³C3/¹³C4, [U-¹³C]glycerol was infused in lieu of [1-¹³C]acetate during a separate visit in a subset of ND (n = 7) subjects. Ratio of ¹³C3/¹³C4 obtained following either tracer was <1.0 at baseline and during clamp, indicating that TPI exchange was essentially complete and did not contribute to asymmetric glucose enrichment. Uncorrected and corrected rates of gluconeogenesis were no different (P = not significant) in T2DM vs. ND both at baseline and during clamp. TA correction resulted in equivalent estimates of corrected gluconeogenesis in T2DM and ND that were ~25-35% lower than uncorrected gluconeogenesis both at baseline and during the clamp. The asymmetric enrichment of glucose from ¹³C-gluconeogenic tracers is attributable to TA exchange and can be utilized to correct for TA exchange. In conclusion, TA exchange does not differ between T2DM and ND under fasting or hyperglycemic clamp conditions, and the ²H₂O method continues to provide an accurate estimation of gluconeogenesis.
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Affiliation(s)
- Aman Rajpal
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, Minnesota
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Impact of short term consumption of diets high in either non-starch polysaccharides or resistant starch in comparison with moderate weight loss on indices of insulin sensitivity in subjects with metabolic syndrome. Nutrients 2013; 5:2144-72. [PMID: 23752495 PMCID: PMC3725498 DOI: 10.3390/nu5062144] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/06/2013] [Accepted: 05/28/2013] [Indexed: 11/16/2022] Open
Abstract
This study investigated if additional non-starch polysaccharide (NSP) or resistant starch (RS), above that currently recommended, leads to better improvement in insulin sensitivity (IS) than observed with modest weight loss (WL). Obese male volunteers (n = 14) were given an energy-maintenance (M) diet containing 27 g NSP and 5 g RS daily for one week. They then received, in a cross-over design, energy-maintenance intakes of either an NSP-enriched diet (42 g NSP, 2.5 g RS) or an RS-enriched diet (16 g NSP, 25 g RS), each for three weeks. Finally, a high protein (30% calories) WL diet was provided at 8 MJ/day for three weeks. During each dietary intervention, endogenous glucose production (EGP) and IS were assessed. Fasting glycaemia was unaltered by diet, but plasma insulin and C-peptide both decreased with the WL diet (p < 0.001), as did EGP (-11%, p = 0.006). Homeostatis model assessment of insulin resistance improved following both WL (p < 0.001) and RS (p < 0.05) diets. Peripheral tissue IS improved only with WL (57%-83%, p < 0.005). Inclusion of additional RS or NSP above amounts currently recommended resulted in little or no improvement in glycaemic control, whereas moderate WL (approximately 3 kg fat) improved IS.
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Hsu FL, Huang CF, Chen YW, Yen YP, Wu CT, Uang BJ, Yang RS, Liu SH. Antidiabetic effects of pterosin A, a small-molecular-weight natural product, on diabetic mouse models. Diabetes 2013; 62:628-38. [PMID: 23069626 PMCID: PMC3554375 DOI: 10.2337/db12-0585] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The therapeutic effect of pterosin A, a small-molecular-weight natural product, on diabetes was investigated. Pterosin A, administered orally for 4 weeks, effectively improved hyperglycemia and glucose intolerance in streptozotocin, high-fat diet-fed, and db/db diabetic mice. There were no adverse effects in normal or diabetic mice treated with pterosin A for 4 weeks. Pterosin A significantly reversed the increased serum insulin and insulin resistance (IR) in dexamethasone-IR mice and in db/db mice. Pterosin A significantly reversed the reduced muscle GLUT-4 translocation and the increased liver phosphoenolpyruvate carboxyl kinase (PEPCK) expression in diabetic mice. Pterosin A also significantly reversed the decreased phosphorylations of AMP-activated protein kinase (AMPK) and Akt in muscles of diabetic mice. The decreased AMPK phosphorylation and increased p38 phosphorylation in livers of db/db mice were effectively reversed by pterosin A. Pterosin A enhanced glucose uptake and AMPK phosphorylation in cultured human muscle cells. In cultured liver cells, pterosin A inhibited inducer-enhanced PEPCK expression, triggered the phosphorylations of AMPK, acetyl CoA carboxylase, and glycogen synthase kinase-3, decreased glycogen synthase phosphorylation, and increased the intracellular glycogen level. These findings indicate that pterosin A may be a potential therapeutic option for diabetes.
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Affiliation(s)
- Feng-Lin Hsu
- Graduate Institute of Pharmacognosy, Taipei Medical University, Taipei, Taiwan
| | - Chun-Fa Huang
- Graduate Institute of Chinese Medical Science, School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Ya-Wen Chen
- Department of Physiology, China Medical University, Taichung, Taiwan
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan
| | - Yuan-Peng Yen
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Cheng-Tien Wu
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Biing-Jiun Uang
- Department of Chemistry, College of Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Rong-Sen Yang
- Department of Orthopaedics, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shing-Hwa Liu
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Urology, College of Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Corresponding author: Shing-Hwa Liu,
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König M, Holzhütter HG. Kinetic modeling of human hepatic glucose metabolism in type 2 diabetes mellitus predicts higher risk of hypoglycemic events in rigorous insulin therapy. J Biol Chem 2012; 287:36978-89. [PMID: 22977253 DOI: 10.1074/jbc.m112.382069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A major problem in the insulin therapy of patients with diabetes type 2 (T2DM) is the increased occurrence of hypoglycemic events which, if left untreated, may cause confusion or fainting and in severe cases seizures, coma, and even death. To elucidate the potential contribution of the liver to hypoglycemia in T2DM we applied a detailed kinetic model of human hepatic glucose metabolism to simulate changes in glycolysis, gluconeogenesis, and glycogen metabolism induced by deviations of the hormones insulin, glucagon, and epinephrine from their normal plasma profiles. Our simulations reveal in line with experimental and clinical data from a multitude of studies in T2DM, (i) significant changes in the relative contribution of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization; (ii) decreased postprandial glycogen storage as well as increased glycogen depletion in overnight fasting and short term fasting; and (iii) a shift of the set point defining the switch between hepatic glucose production and hepatic glucose utilization to elevated plasma glucose levels, respectively, in T2DM relative to normal, healthy subjects. Intriguingly, our model simulations predict a restricted gluconeogenic response of the liver under impaired hormonal signals observed in T2DM, resulting in an increased risk of hypoglycemia. The inability of hepatic glucose metabolism to effectively counterbalance a decline of the blood glucose level becomes even more pronounced in case of tightly controlled insulin treatment. Given this Janus face mode of action of insulin, our model simulations underline the great potential that normalization of the plasma glucagon profile may have for the treatment of T2DM.
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Affiliation(s)
- Matthias König
- Institute of Biochemistry, University Medicine Charité Berlin, 10117 Berlin, Germany.
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Quantifying the contribution of the liver to glucose homeostasis: a detailed kinetic model of human hepatic glucose metabolism. PLoS Comput Biol 2012; 8:e1002577. [PMID: 22761565 PMCID: PMC3383054 DOI: 10.1371/journal.pcbi.1002577] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 05/08/2012] [Indexed: 02/02/2023] Open
Abstract
Despite the crucial role of the liver in glucose homeostasis, a detailed mathematical model of human hepatic glucose metabolism is lacking so far. Here we present a detailed kinetic model of glycolysis, gluconeogenesis and glycogen metabolism in human hepatocytes integrated with the hormonal control of these pathways by insulin, glucagon and epinephrine. Model simulations are in good agreement with experimental data on (i) the quantitative contributions of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization under varying physiological states. (ii) the time courses of postprandial glycogen storage as well as glycogen depletion in overnight fasting and short term fasting (iii) the switch from net hepatic glucose production under hypoglycemia to net hepatic glucose utilization under hyperglycemia essential for glucose homeostasis (iv) hormone perturbations of hepatic glucose metabolism. Response analysis reveals an extra high capacity of the liver to counteract changes of plasma glucose level below 5 mM (hypoglycemia) and above 7.5 mM (hyperglycemia). Our model may serve as an important module of a whole-body model of human glucose metabolism and as a valuable tool for understanding the role of the liver in glucose homeostasis under normal conditions and in diseases like diabetes or glycogen storage diseases.
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Wu X, Williams KJ. NOX4 pathway as a source of selective insulin resistance and responsiveness. Arterioscler Thromb Vasc Biol 2012; 32:1236-45. [PMID: 22328777 DOI: 10.1161/atvbaha.111.244525] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Type 2 diabetes mellitus and related syndromes exhibit a deadly triad of dyslipoproteinemia, which leads to atherosclerosis; hyperglycemia, which causes microvascular disease; and hypertension. These features share a common, but unexplained, origin-namely, pathway-selective insulin resistance and responsiveness. Here, we undertook a comprehensive characterization of pathway-selective insulin resistance and responsiveness in liver and hepatocytes by examining 18 downstream targets of the insulin receptor, surveying the AKT, ERK, and NAD(P)H oxidase 4 pathways. METHODS AND RESULTS Injection of insulin into hyperphagic, obese type 2 diabetic db/db mice failed to inactivate hepatic protein tyrosine phosphatase gene family members, a crucial action of NAD(P)H oxidase 4 previously thought to be required for all signaling through AKT and ERK. Insulin-stimulated type 2 diabetic livers unexpectedly produced an unusual form of AKT that was phosphorylated at Thr308 (pT308), with only weak insulin-stimulated phosphorylation at Ser473. Remarkably, knockdown or inhibition of NAD(P)H oxidase 4 in cultured hepatocytes recapitulated the entire complicated pattern of pathway-selective insulin resistance and responsiveness seen in vivo-namely, monophosphorylated pT308-AKT, impaired insulin-stimulated pathways for lowering plasma lipids and glucose, but continued lipogenic pathways and robust ERK activation. CONCLUSIONS Functional disturbance of a single molecule, NAD(P)H oxidase 4, is sufficient to induce the key harmful features of deranged insulin signaling in type 2 diabetes mellitus, obesity, and other conditions associated with hyperinsulinemia and pathway-selective insulin resistance and responsiveness.
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Affiliation(s)
- Xiangdong Wu
- Section of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Gastaldelli A. Role of beta-cell dysfunction, ectopic fat accumulation and insulin resistance in the pathogenesis of type 2 diabetes mellitus. Diabetes Res Clin Pract 2011; 93 Suppl 1:S60-5. [PMID: 21864753 DOI: 10.1016/s0168-8227(11)70015-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In the natural history of type 2 diabetes (T2DM), individuals progress from normal glucose tolerance (NGT) to impaired glucose tolerance (IGT) to overt T2DM and this progression has been demonstrated in populations of diverse ethnic background. It is widely recognised that both insulin resistance and beta-cell dysfunction are important in the pathogenesis of glucose intolerance. In populations with a high prevalence of T2DM, insulin resistance is well established long before the development of any impairment in glucose homeostasis, particularly in subjects with ectopic fat accumulation. However, as long as the beta cell is able to secrete sufficient amounts of insulin to offset the severity of insulin resistance, glucose tolerance remains normal. This dynamic interaction between insulin secretion and insulin resistance is essential to the maintenance of NGT and interruption of this crosstalk between the beta cell and peripheral tissues results in the progressive deterioration of glucose homeostasis. In this paper the role of beta-cell function is reviewed, as well as the role of ectopic fat accumulation and insulin resistance in the development of type 2 diabetes.
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Affiliation(s)
- Amalia Gastaldelli
- Institute of Clinical Physiology, National Research Council (CNR), Pisa, Italy.
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46
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Lin HV, Accili D. Hormonal regulation of hepatic glucose production in health and disease. Cell Metab 2011; 14:9-19. [PMID: 21723500 PMCID: PMC3131084 DOI: 10.1016/j.cmet.2011.06.003] [Citation(s) in RCA: 307] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 05/28/2011] [Accepted: 06/08/2011] [Indexed: 01/06/2023]
Abstract
We review mechanisms that regulate production of glucose by the liver, focusing on areas of budding consensus, and endeavoring to provide a candid assessment of lingering controversies. We also attempt to reconcile data from tracer studies in humans and large animals with the growing compilation of mouse knockouts that display changes in glucose production. A clinical hallmark of diabetes, excessive glucose production remains key to its treatment. Hence, we attempt to integrate emerging pathways into the broader goal to rejuvenate the staid antidiabetic pharmacopeia.
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Affiliation(s)
- Hua V Lin
- Merck Research Laboratories, Rahway, NJ 07065, USA
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47
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Basu R, Barosa C, Basu A, Pattan V, Saad A, Jones J, Rizza R. Transaldolase exchange and its effects on measurements of gluconeogenesis in humans. Am J Physiol Endocrinol Metab 2011; 300:E296-303. [PMID: 21062960 PMCID: PMC3043622 DOI: 10.1152/ajpendo.00403.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The deuterated water method is used extensively to measure gluconeogenesis in humans. This method assumes negligible exchange of the lower three carbons of fructose 6-phsophate via transaldolase exchange since this exchange will result in enrichment of carbon 5 of glucose in the absence of net gluconeogenesis. The present studies tested this assumption. ²H₂O and acetaminophen were ingested and [1-¹³C]acetate infused in 11 nondiabetic subjects after a 16-h fast. Plasma and urinary glucuronide enrichments were measured using nuclear magnetic resonance spectroscopy before and during a 0.35 mU·kg FFM⁻¹·min⁻¹ insulin infusion. Rates of endogenous glucose production measured with [3-³H]- and [6,6-²H₂]glucose did not differ either before (14.0 ± 0.7 vs. 13.8 ± 0.7 μmol·kg⁻¹·min⁻¹) or during the clamp (10.4 ± 0.9 vs. 10.9 ± 0.7 μmol·kg⁻¹·min⁻¹), consistent with equilibration and quantitative removal of tritium during triose isomerase exchange. Plasma [3-¹³C] glucose-to-[4-¹³C]glucose and urinary [3-¹³C] glucuronide-to-[4-¹³C]glucuronide ratios were <1.0 (P < 0.001) in all subjects both before (0.66 ± 0.04 and 0.60 ± 0.04) and during (059 ± 0.05 and 0.56 ± 0.06) the insulin infusion, respectively, indicating that ∼35-45% of the labeling of the 5th carbon of glucose by deuterium was due to transaldolase exchange rather than gluconeogenesis. When corrected for transaldolase exchange, rates of gluconeogenesis were lower (P < 0.001) and glycogenolysis higher (P < 0.001) than uncorrected rates both before and during the insulin infusion. In conclusion, assuming negligible dilution by glycerol and near-complete triose isomerase equilibration, these data provide strong experimental evidence that transaldolase exchange occurs in humans, resulting in an overestimate of gluconeogenesis and an underestimate of glycogenolysis when measured with the ²H₂O method. Use of appropriate ¹³C tracers provides a means of correcting for transaldolase exchange.
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Affiliation(s)
- Rita Basu
- Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
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Fructose-1, 6-bisphosphatase inhibitors for reducing excessive endogenous glucose production in type 2 diabetes. Handb Exp Pharmacol 2011:279-301. [PMID: 21484576 DOI: 10.1007/978-3-642-17214-4_12] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fructose-1,6-bisphosphatase (FBPase), a rate-controlling enzyme of gluconeogenesis, has emerged as an important target for the treatment of type 2 diabetes due to the well-recognized role of excessive endogenous glucose production (EGP) in the hyperglycemia characteristic of the disease. Inhibitors of FBPase are expected to fulfill an unmet medical need because the majority of current antidiabetic medications act primarily on insulin resistance or insulin insufficiency and do not reduce gluconeogenesis effectively or in a direct manner. Despite significant challenges, potent and selective inhibitors of FBPase targeting the allosteric site of the enzyme were identified by means of a structure-guided design strategy that used the natural inhibitor, adenosine monophosphate (AMP), as the starting point. Oral delivery of these anionic FBPase inhibitors was enabled by a novel diamide prodrug class. Treatment of diabetic rodents with CS-917, the best characterized of these prodrugs, resulted in a reduced rate of gluconeogenesis and EGP. Of note, inhibition of gluconeogenesis by CS-917 led to the amelioration of both fasting and postprandial hyperglycemia without weight gain, incidence of hypoglycemia, or major perturbation of lactate or lipid homeostasis. Furthermore, the combination of CS-917 with representatives of the insulin sensitizer or insulin secretagogue drug classes provided enhanced glycemic control. Subsequent clinical evaluations of CS-917 revealed a favorable safety profile as well as clinically meaningful reductions in fasting glucose levels in patients with T2DM. Future trials of MB07803, a second generation FBPase inhibitor with improved pharmacokinetics, will address whether this novel class of antidiabetic agents can provide safe and long-term glycemic control.
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van der Heijden GJ, Wang ZJ, Chu Z, Toffolo G, Manesso E, Sauer PJ, Sunehag AL. Strength exercise improves muscle mass and hepatic insulin sensitivity in obese youth. Med Sci Sports Exerc 2010; 42:1973-80. [PMID: 20351587 PMCID: PMC2944907 DOI: 10.1249/mss.0b013e3181df16d9] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Data on the metabolic effects of resistance exercise (strength training) in adolescents are limited. PURPOSE The objective of this study was to determine whether a controlled resistance exercise program without dietary intervention or weight loss reduces body fat accumulation, increases lean body mass, and improves insulin sensitivity and glucose metabolism in sedentary obese Hispanic adolescents. METHODS Twelve obese adolescents (age = 15.5 ± 0.5 yr, body mass index = 35.3 ± 0.8 kg·m; 40.8% ± 1.5% body fat) completed a 12-wk resistance exercise program (two times 1 h·wk, exercising all major muscle groups). At baseline and on completion of the program, body composition was measured by dual-energy x-ray absorptiometry, abdominal fat distribution was measured by magnetic resonance imaging, hepatic and intramyocellular fat was measured by magnetic resonance spectroscopy, peripheral insulin sensitivity was measured by the stable-label intravenous glucose tolerance test, and hepatic insulin sensitivity was measured by the hepatic insulin sensitivity index = 1000/(GPR × fasting insulin). Glucose production rate (GPR), gluconeogenesis, and glycogenolysis were quantified using stable isotope gas chromatography/mass spectrometry techniques. RESULTS All participants were normoglycemic. The exercise program resulted in significant strength gain in both upper and lower body muscle groups. Body weight increased from 97.0 ± 3.8 to 99.6 ± 4.2 kg (P < 0.01). The major part (∼80%) was accounted for by increased lean body mass (55.7 ± 2.8 to 57.9 ± 3.0 kg, P ≤ 0.01). Total, visceral, hepatic, and intramyocellular fat contents remained unchanged. Hepatic insulin sensitivity increased by 24% ± 9% (P < 0.05), whereas peripheral insulin sensitivity did not change significantly. GPR decreased by 8% ± 1% (P < 0.01) because of a 12% ± 5% decrease in glycogenolysis (P < 0.05). CONCLUSIONS We conclude that a controlled resistance exercise program without weight loss increases strength and lean body mass, improves hepatic insulin sensitivity, and decreases GPR without affecting total fat mass or visceral, hepatic, and intramyocellular fat contents.
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Affiliation(s)
| | - Zhiyue J. Wang
- Children’s Medical Center and University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Zili Chu
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Gianna Toffolo
- Department of Electronics and Informatics, University of Padua, Italy
| | - Erica Manesso
- Department of Electronics and Informatics, University of Padua, Italy
| | - Pieter J.J. Sauer
- Department of Pediatrics, Beatrix Children’s Hospital, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Agneta L. Sunehag
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
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Iaconelli A, Gastaldelli A, Chiellini C, Gniuli D, Favuzzi A, Binnert C, Macé K, Mingrone G. Effect of oral sebacic Acid on postprandial glycemia, insulinemia, and glucose rate of appearance in type 2 diabetes. Diabetes Care 2010; 33:2327-32. [PMID: 20724647 PMCID: PMC2963488 DOI: 10.2337/dc10-0663] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Dicarboxylic acids are natural products with the potential of being an alternate dietary source of energy. We aimed to evaluate the effect of sebacic acid (a 10-carbon dicarboxylic acid; C10) ingestion on postprandial glycemia and glucose rate of appearance (Ra) in healthy and type 2 diabetic subjects. Furthermore, the effect of C10 on insulin-mediated glucose uptake and on GLUT4 expression was assessed in L6 muscle cells in vitro. RESEARCH DESIGN AND METHODS Subjects ingested a mixed meal (50% carbohydrates, 15% proteins, and 35% lipids) containing 0 g (control) or 10 g C10 in addition to the meal or 23 g C10 as a substitute of fats. RESULTS In type 2 diabetic subjects, the incremental glucose area under the curve (AUC) decreased by 42% (P<0.05) and 70% (P<0.05) in the 10 g C10 and 23 g C10 groups, respectively. At the largest amounts used, C10 reduced the glucose AUC in healthy volunteers also. When fats were substituted with 23 g C10, AUC of Ra was significantly reduced on the order of 18% (P<0.05) in both healthy and diabetic subjects. The insulin-dependent glucose uptake by L6 cells was increased in the presence of C10 (38.7±10.3 vs. 11.4±5.4%; P=0.026). This increase was associated with a 1.7-fold raise of GLUT4. CONCLUSIONS Sebacic acid significantly reduced hyperglycemia after a meal in type 2 diabetic subjects. This beneficial effect was associated with a reduction in glucose Ra, probably due to lowered hepatic glucose output and increased peripheral glucose disposal.
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Affiliation(s)
- Amerigo Iaconelli
- Department of Internal Medicine, Catholic University of Rome, Rome, Italy
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