Dataset Information

Nyman2011_M3Hierarachical_InsulinGlucosedynamics

ABSTRACT: This a model from the article: A Hierarchical Whole-body Modeling Approach Elucidates the Link between in Vitro Insulin Signaling and in Vivo Glucose Homeostasis. Nyman E, Brannmark C, Palmer R, Brugard J, Nystrom FH, Stralfors P, Cedersund G.J Biol Chem.2011 Jul 22;286(29):26028-41. 21572040, Abstract: Type 2 diabetes is a metabolic disease that profoundly affects energy homeostasis. The disease involves failure at several levels and subsystems and is characterized by insulin resistance in target cells and tissues (i.e. by impaired intracellular insulin signaling). We have previously used an iterative experimental-theoretical approach to unravel the early insulin signaling events in primary human adipocytes. That study, like most insulin signaling studies, is based on in vitro experimental examination of cells, and the in vivo relevance of such studies for human beings has not been systematically examined. Herein, we develop a hierarchical model of the adipose tissue, which links intracellular insulin control of glucose transport in human primary adipocytes with whole-body glucose homeostasis. An iterative approach between experiments and minimal modeling allowed us to conclude that it is not possible to scale up the experimentally determined glucose uptake by the isolated adipocytes to match the glucose uptake profile of the adipose tissue in vivo. However, a model that additionally includes insulin effects on blood flow in the adipose tissue and GLUT4 translocation due to cell handling can explain all data, but neither of these additions is sufficient independently. We also extend the minimal model to include hierarchical dynamic links to more detailed models (both to our own models and to those by others), which act as submodules that can be turned on or off. The resulting multilevel hierarchical model can merge detailed results on different subsystems into a coherent understanding of whole-body glucose homeostasis. This hierarchical modeling can potentially create bridges between other experimental model systems and the in vivo human situation and offers a framework for systematic evaluation of the physiological relevance of in vitro obtained molecular/cellular experimental data. This model originates from BioModels Database: A Database of Annotated Published Models (http://www.ebi.ac.uk/biomodels/). It is copyright (c) 2005-2011 The BioModels.net Team. For more information see the terms of use. To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.

DISEASE(S): Diabetes Mellitus

SUBMITTER: Ishan Ajmera

PROVIDER: BIOMD0000000356 | BioModels | 2011-08-19

REPOSITORIES: BioModels

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Publications

A hierarchical whole-body modeling approach elucidates the link between in Vitro insulin signaling and in Vivo glucose homeostasis.

Nyman Elin E Brännmark Cecilia C Palmér Robert R Brugård Jan J Nyström Fredrik H FH Strålfors Peter P Cedersund Gunnar G

The Journal of biological chemistry 20110513 29

Type 2 diabetes is a metabolic disease that profoundly affects energy homeostasis. The disease involves failure at several levels and subsystems and is characterized by insulin resistance in target cells and tissues (i.e. by impaired intracellular insulin signaling). We have previously used an iterative experimental-theoretical approach to unravel the early insulin signaling events in primary human adipocytes. That study, like most insulin signaling studies, is based on in vitro experimental exa ...[more]

PMID: 21572040

Publication: 1/2

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Project description:Background: Systemic glucose homeostasis is affected by adipose cell function. Still, the cellular events preceding the onset of insulin resistance in adipocytes are not yet resolved. To capture the immediate cellular changes during diet-induced expansion of cell volume and number, we characterized the initial changes in mature adipocytes during a short high fat diet (HFD) intervention. Methods: C57BL6/J male mice were fed chow diet, and switched to HFD for 2, 4, 6 or 14 days. Systemic glucose clearance was assessed by glucose tolerance test. Adipose tissue was dissected for RNA seq analysis and cell size distribution analyzed using coulter counter technique. Insulin response in isolated adipocytes was measured by glucose uptake and Western blotting of insulin signaling intermediates. Confocal microscopy was used to assess autophagic flux in cells pre-incubated with rapamycin and chloroquine. Results: Switching to HFD was accompanied by an immediate adipose cell size expansion followed by recruitment of new adipocytes. Despite an increase in both basal and insulin-stimulated glucose uptake in adipocytes, we observed a progressive decrease in insulin-stimulated activation of Protein Kinase B (PKB) Ser473, PKB Thr308 and Akt substrate of 160 (AS160) Tyr642, and onset of systemic insulin-resistance already after two days. Moreover, RNA-seq analysis of adipose tissue revealed marked changes in gene expression at day four, of which the most significant included genes directly involved in autophagy (Trp53Inp2 and Beclin1). Enhanced autophagy was observed in isolated adipocytes from HFD-fed mice, detected as an increased density of LC3-positive puncta by confocal microscopy, and increase of LC3II. Conclusions: HFD rapidly caused impaired insulin signal transduction in adipocytes, while both basal and insulin-stimulated glucose uptake increased, which support the concept of spare signaling. Interestingly, our data suggests autophagy as one of the early cellular events that could contribute to insulin resistance.

Project description:Background. Obesity and body fat distribution are important risk factors for the development of type 2 diabetes and metabolic syndrome. Evidence has accumulated that this risk is related to intrinsic differences in behavior of adipocytes in different fat depots. LIM Domain Only 3 (LMO3) plays a crucial role in adipogenesis modulating the key adipogenic master switch PPARγ in human, but not mouse, visceral adipose progenitors; however, despite high expression in mature adipocytes, its function in these cells is currently unknown. Aims/Hypothesis. The aim of this study was to determine the potential involvement of LMO3-dependent pathways in the modulation of key functions of mature adipocytes during obesity. Methods. Based on a recently engineered hybrid rAAV serotype Rec2 shown to efficiently transduce both brown adipose tissue (BAT) and white adipose tissue (WAT), we delivered YFP or Lmo3 to epididymal WAT (eWAT) of C57Bl6/J mice on a high fat diet (HFD). The effects of eWAT transduction on metabolic parameters were evaluated 10 weeks later. To further define the role of LMO3 in insulin-stimulated glucose uptake, insulin signaling, adipocyte bioenergetics as well as endocrine function, experiments were conducted in 3T3-L1 adipocytes and newly differentiated human primary mature adipocytes, engineered for transient gain- or loss of LMO3 expression, respectively.Results. AAV transduction of eWAT results in strong and stable Lmo3 expression specifically in the adipocyte fraction over a course of 10 weeks with HFD feeding. Lmo3 expression in eWAT significantly improved glucose clearance and insulin sensitivity in diet-induced obesity, paralleled by increased serum adiponectin. In vitro, Lmo3 expression in 3T3-L1 adipocytes increased insulin-stimulated GLUT4 translocation and glucose uptake as well as mitochondrial oxidative capacity in addition to fatty acid oxidation. On a molecular level, LMO3 augmented PPARg activity, oxidative mitochondrial gene expression, which depended on and the expression of the PPARg co-activator Ncoa1, which was required for LMO3 effects on mitochondria and glucose uptake. In human mature adipocytes, LMO3 overexpression promoted, while silencing of LMO3 suppressed mitochondrial oxidative capacity. Conclusions. LMO3 expression in visceral adipose tissue regulates multiple genes that preserve adipose tissue functionality during obesity, such as glucose tolerance, insulin sensitivity and adiponectin secretion. Together with increased PPARγ activity, these gene expression changes promote insulin-induced GLUT4 translocation, glucose uptake in addition to increased mitochondrial oxidative capacity, limiting HFD-induced adipose dysfunction. These data add LMO3 as a novel regulator improving visceral adipose tissue function during obesity.

Dataset Information

Nyman2011_M3Hierarachical_InsulinGlucosedynamics

Publications

A hierarchical whole-body modeling approach elucidates the link between in Vitro insulin signaling and in Vivo glucose homeostasis.

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