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Kumashiro N, Beddow SA, Vatner DF, Majumdar SK, Cantley JL, Guebre-Egziabher F, Fat I, Guigni B, Jurczak MJ, Birkenfeld AL, Kahn M, Perler BK, Puchowicz MA, Manchem VP, Bhanot S, Still CD, Gerhard GS, Petersen KF, Cline GW, Shulman GI, Samuel VT. Targeting pyruvate carboxylase reduces gluconeogenesis and adiposity and improves insulin resistance. Diabetes 2013; 62:2183-94. [PMID: 23423574 PMCID: PMC3712050 DOI: 10.2337/db12-1311] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We measured the mRNA and protein expression of the key gluconeogenic enzymes in human liver biopsy specimens and found that only hepatic pyruvate carboxylase protein levels related strongly with glycemia. We assessed the role of pyruvate carboxylase in regulating glucose and lipid metabolism in rats through a loss-of-function approach using a specific antisense oligonucleotide (ASO) to decrease expression predominantly in liver and adipose tissue. Pyruvate carboxylase ASO reduced plasma glucose concentrations and the rate of endogenous glucose production in vivo. Interestingly, pyruvate carboxylase ASO also reduced adiposity, plasma lipid concentrations, and hepatic steatosis in high fat-fed rats and improved hepatic insulin sensitivity. Pyruvate carboxylase ASO had similar effects in Zucker Diabetic Fatty rats. Pyruvate carboxylase ASO did not alter de novo fatty acid synthesis, lipolysis, or hepatocyte fatty acid oxidation. In contrast, the lipid phenotype was attributed to a decrease in hepatic and adipose glycerol synthesis, which is important for fatty acid esterification when dietary fat is in excess. Tissue-specific inhibition of pyruvate carboxylase is a potential therapeutic approach for nonalcoholic fatty liver disease, hepatic insulin resistance, and type 2 diabetes.
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Affiliation(s)
- Naoki Kumashiro
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Sara A. Beddow
- Veterans Affairs Medical Center, West Haven, Connecticut
| | - Daniel F. Vatner
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Sachin K. Majumdar
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Jennifer L. Cantley
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | | | - Ioana Fat
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Blas Guigni
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Michael J. Jurczak
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Andreas L. Birkenfeld
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Mario Kahn
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Bryce K. Perler
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | | | | | | | | | - Glenn S. Gerhard
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania
| | - Kitt Falk Petersen
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Gary W. Cline
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Gerald I. Shulman
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Varman T. Samuel
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Veterans Affairs Medical Center, West Haven, Connecticut
- Corresponding author: Varman T. Samuel,
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Abstract
Subcutaneous insulin absorption is a complex process, whose quantitative aspects have important clinical implications. In this review we briefly discuss the rationale of modelling techniques before introducing some of the more common types of models (empirical vs mechanistic, simple vs complex, compartmental) found in the biological literature. The various approaches are compared regarding their suitability to model subcutaneous absorption of insulin. Methods are described (monitoring residual depot activity or the appearance of insulin in the systemic circulation) which allow the determination of model parameters from experimental data. The degree to which current model predictions describe the available experimental data is discussed. Since the absorption of insulin involves a number of poorly understood events it would be difficult, at this time, to construct a complex model which completely describes all aspects of the absorption process. Although the simpler techniques (such as the use of a one-pool model) provide only an approximate description of subcutaneous kinetics they are likely to remain useful tools in routine investigation.
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Affiliation(s)
- S M Furler
- Garvan Institue of Medical Research, St Vincent's Hospital, Sydney, Australia
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Thorsteinsson B, Fugleberg S, Feldt-Rasmussen B, Binder C. Kinetic models for plasma disappearance of insulin in normal subjects. ACTA PHARMACOLOGICA ET TOXICOLOGICA 1985; 57:309-16. [PMID: 3911734 DOI: 10.1111/j.1600-0773.1985.tb00050.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Three theoretical kinetic models for plasma disappearance of insulin were examined in six normal men. The models allowed for the existence of non-saturable and/or saturable mechanisms. Constant infusion of porcine insulin at different rates was used to achieve different levels of steady state plasma insulin concentrations, while normoglycaemia was secured by a glucose clamp technique. Appropriate validation procedures demonstrated that one of the three models was superior to the others in describing the relationship between the exogenous insulin infusion rate Iex and the steady state plasma insulin concentration C: Iex = -Iend + k2 X C/(k3 + C), where Iend is the endogenous post-hepatic insulin delivery rate. Thus, only saturable mechanism(s) could be demonstrated. The median value of k2 (the maximal insulin disappearance rate) and k3 (the plasma insulin concentration at which the insulin disappearance rate is half maximal) were 7.31 nmol X min.-1 and 3.89 nmol X 1-1. The median value of k2/k3 (the clearance rate of insulin for infinitesimal plasma insulin concentrations) was 25.0 ml X kg-1 X min.-1. Thus, at physiological levels of plasma insulin concentrations the metabolic clearance rate of insulin is higher than insulin clearance estimates previously reported in studies based on the assumption of first order kinetics.
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