The long-term objective of this research program is to identify potential targets for obesity drugs that act on WAT to reduce body fat. Obesity is increasingly becoming a leading health problem in developed countries, especially the U.S. Epidemiological data point to increased body fat (white adipose tissue, WAT) mass as a chief contributor to obesity, which occurs both by increases in fat cell size and number. The effects of current dietary therapies are mostly reversible, and less than 10 % of those who lose weight are able to maintain the weight loss. Recent evidence paints an increasingly complex picture of metabolic regulation within the adipose tissue, which secretes autocrine, paracrine, and endocrine factors that regulate adipose cellular and whole body energy metabolism. In light of this picture, a promising alternative to reducing food intake or inhibiting digestive fat absorption is to reduce WAT mass by directly influencing adipose cellular metabolism. Recognizing the complexity of cellular metabolic regulation, this research takes a novel, systems oriented approach. Addressing the knowledge gap left by gene and protein expression profiling studies, this proposal focuses on obtaining comprehensive metabolic information on obese and non-obese adipose cellular growth. The project develops by: 1) developing tissue-engineered model systems for obese and normal adipose cellular growth, 2) profiling associated changes to extracellular metabolite concentrations and intracellular metabolic fluxes, and 3) identifying discriminatory markers characteristic of the various stages (pre- vs. mature adipocyte) and/or types (obese vs. normal) of adipose cellular growth.
These specific aims will be achieved by performing the following tasks: a) Compare the differentiation and growth of obese (Ob17) and non-obese (3T3-L1) adipocyte precursor cells, first in static, then bioreactor cultures. Comparisons will be made, among others, on the basis of morphology, biochemical function (including insulin sensitivity), and growth rate. Micro-fluidic bioreactor experiments will perform comparisons of Ob17 and 3T3-L1 cells in co-culture, b) Generate metabolic profile libraries encompassing concentration changes for all major primary carbohydrate, amino acid, and lipid metabolites in culture media. The primary analytical method will be liquid chromatography, c) Generate parallel metabolic flux libraries using established modeling methodologies, d) Perform multivariate discriminant analysis on the metabolite and flux libraries to identify significant markers for each of the growth conditions. The expected outcome of these procedures is a comprehensive library of metabolic profiles and markers that capture both broad and unique features of obese and normal adipose growth. This knowledge output marks a significant first step, at the functional level, in the global study of adipose energy metabolism, and should serve as a necessary information platform for further studies that investigate major driving reactions in adipose growth as obesity drug targets.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21DK067228-02
Application #
6850910
Study Section
Special Emphasis Panel (ZRG1-SSS-H (90))
Program Officer
Haft, Carol R
Project Start
2004-05-01
Project End
2006-04-30
Budget Start
2005-05-01
Budget End
2006-04-30
Support Year
2
Fiscal Year
2005
Total Cost
$155,000
Indirect Cost
Name
Tufts University
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
073134835
City
Medford
State
MA
Country
United States
Zip Code
02155
Si, Yaguang; Shi, Hai; Lee, Kyongbum (2009) Impact of perturbed pyruvate metabolism on adipocyte triglyceride accumulation. Metab Eng 11:382-90
Lai, Ning; Jayaraman, Arul; Lee, Kyongbum (2009) Enhanced proliferation of human umbilical vein endothelial cells and differentiation of 3T3-L1 adipocytes in coculture. Tissue Eng Part A 15:1053-61
Si, Yaguang; Shi, Hai; Lee, Kyongbum (2009) Metabolic flux analysis of mitochondrial uncoupling in 3T3-L1 adipocytes. PLoS One 4:e7000
Yoon, Jeongah; Si, Yaguang; Nolan, Ryan et al. (2007) Modular decomposition of metabolic reaction networks based on flux analysis and pathway projection. Bioinformatics 23:2433-40
Senocak, Fatih S; Si, Yaguang; Moya, Colby et al. (2007) Effect of uncoupling protein-1 expression on 3T3-L1 adipocyte gene expression. FEBS Lett 581:5865-71
Yoon, Jeongah; Lee, Kyongbum (2007) Metabolic flux profiling of reaction modules in liver drug transformation. Pac Symp Biocomput :193-204
Si, Yaguang; Yoon, Jeongah; Lee, Kyongbum (2007) Flux profile and modularity analysis of time-dependent metabolic changes of de novo adipocyte formation. Am J Physiol Endocrinol Metab 292:E1637-46
Si, Yaguang; Palani, Santhosh; Jayaraman, Arul et al. (2007) Effects of forced uncoupling protein 1 expression in 3T3-L1 cells on mitochondrial function and lipid metabolism. J Lipid Res 48:826-36
Nolan, Ryan P; Fenley, Andrew P; Lee, Kyongbum (2006) Identification of distributed metabolic objectives in the hypermetabolic liver by flux and energy balance analysis. Metab Eng 8:30-45