1. Managed by UT-Battelle for the Department of Energy 1 Mathematical Modeling of Fatty Acid Oxidation in Skeletal Muscle Cells Sheds New Light on Obesity Presented to Associate Director of the Office of Science Sara Haque Research Alliance in Math and Science Computational Sciences and Engineering Division Mentor: Kara Kruse M.S.E. In collaboration with the Obesity Research Center at the University of Tennessee in Knoxville August 13, 2008 Oak Ridge, Tennessee

2. Managed by UT-Battelle for the Department of Energy 2 Outline  Background of fatty acid oxidation in skeletal muscle cells –Health issues –Previous research  Research objectives  Methods  Conclusion  Future Research

3. Managed by UT-Battelle for the Department of Energy 3 Obesity is a Growing Problem in the United States  Overall health of individuals is decreasing and health care costs are increasing  Factors affecting obesity are numerous –i.e., heart disease, diabetes, high blood pressure  Understanding biochemistry may lead to new ways of controlling obesity  Biochemical cross-talk between skeletal muscle cells and adipocytes, fat cells, may be a key factor in fatty acid oxidation  Developing a model of fatty acid oxidation is the first step

4. Managed by UT-Battelle for the Department of Energy 4 Background: previous experimental research In Vitro experiments by Sun and Zemel (2007) with C2C12 myotubes and 3T3–L1 preadipoctyes cultures show:  Leucine, an essential amino acid, found in dairy increases fatty acid oxidation (FAO)  Calcitriol reduces FAO due to lack of dietary Calcium  Adiponectin, released by adipocytes, increases FAO  UCP3, a transport protein, regulated by leucine and calcitriol controls how much fatty acids enter the mitochondria for oxidation

5. Managed by UT-Battelle for the Department of Energy 5 FFA FAC Fatty acyl-CoA FFC Acetyl-CoA FFA CPT-II CPT-I Β-Oxidation FAC UCP-3 Adipo R Adiponectin AMPK Calcitriol TGL Ca 2+ H+H+ Mitochondria Intermembrane Space Matrix of Mitochondria Cytosol Skeletal Muscle Cell ? ACC H+H+ H+H+ H+H+ H+H+ H+H+ H+H+

6. Managed by UT-Battelle for the Department of Energy 6 FFA FAC Fatty acyl-CoA FFC Acetyl-CoA FFA CPT-II CPT-I Β-Oxidation FAC UCP-3 Adipo R Adiponectin AMPK Leucine TGL Mitochondrial Intermembrane Space Skeletal Muscle Cell Cytosol Matrix of Mitochondria ACC H+H+ H+H+ H+H+ H+H+ H+H+ H+H+

7. Managed by UT-Battelle for the Department of Energy 7 Research Objective  Find a mathematical model that –explains the experimental data, and –sheds light on biochemical processes affecting FAO Allen, 2005

8. Managed by UT-Battelle for the Department of Energy 8 Mathematical model must behave in a physiologically consistent manner  Different equations can fit the same time points  Consider the equations that are physiologically consistent PDGF-BB Fraction Time (Days)

9. Managed by UT-Battelle for the Department of Energy 9 Methods  Analyzed data using Excel  Created a mathematical model based on lumped Michaelis-Menton enzyme kinetics  Developed UCP3 model first  Developed FAO model at three time points at separate steady state solutions  Utilized Mathematica® FindFit function to estimate model parameters  Compared model equations with experimental results  Revised model if discrepancy between results and model occur

10. Managed by UT-Battelle for the Department of Energy 10 Results  Good fit for UCP3  FAO model provides a good fit at 12 and 24 hour data however ongoing work is being conducted for 48 hours

11. Managed by UT-Battelle for the Department of Energy 11 ControlLeucineNifedipineLeucine+Nifedipine ControlLeucineNifedipineLeucine+Nifedipine ControlLeucineNifedipineLeucine+Nifedipine ControlLeucineNifedipineLeucine+Nifedipine ControlLeucineNifedipineLeucine+Nifedipine ControlLeucineNifedipineLeucine+Nifedipine ControlLeucineNifedipineLeucine+Nifedipine Experimental Data vs. Computational Data ControlLeucineNifedipineLeucine + Nifedipine Treatments

12. Managed by UT-Battelle for the Department of Energy 12 Fatty Acid Oxidation at 12 Hours Control Leucine Nifedipine Leucine + Nifedipine

13. Managed by UT-Battelle for the Department of Energy 13 Fatty Acid Oxidation at 24 Hours Control Leucine NifedipineLeucine + Nifedipine

14. Managed by UT-Battelle for the Department of Energy 14 Conclusion Mathematical model incorporating steady state Michaelis-Menton inhibitory kinetics successfully describes the experimental data for UCP3  Leucine has a stimulating effect which is fairly consistent over time  Nifedipine has stimulatory effect which increases significantly over time  Adiponectin has initial stimulatory effect on nifedipine which goes away over time  Adiponectin has inhibitory effect on leucine which increases slightly over time

15. Managed by UT-Battelle for the Department of Energy 15 Future Research  Long-term goal is to develop a mathematical model describing biochemical cross-talk between skeletal muscle cells and adipocytes.  To accomplish this goal the following processes will be modeled – FAO and fatty acid synthesis (FAS) in adipocytes –cross-talk between skeletal muscle cells and adipocytes –effects of Interlukin-6 and Interlukin-15 on the cross-talk between the cells

16. Managed by UT-Battelle for the Department of Energy 16 Collaborations and References  All biochemical expertise and experimental data was provided by Dr. Zemel from the Obesity Research Center at the University of Tennessee in Knoxville. –Sun, Xiaocun and Zemel, Michael. (2007).Leucine and Calcium Regulate Fat Metabolism and Energy Partitioning in Murine Adipocyte and Muscle Cells. Lipids,42(4), A328-A329.  Biochemical Modeling Approach –Allen,Nicholas.(2005). Computational Software for Building Biochemical Reaction Network Models with Differential Equations.

17. Managed by UT-Battelle for the Department of Energy 17 Acknowledgments The Research Alliance in Math and Science program is sponsored by the Office of Advanced Scientific Computing Research, U.S. Department of Energy. The work was performed at the Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC under Contract No. De-AC05-00OR22725. This work has been authored by a contractor of the U.S. Government, accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. Thank you to our sponsor at DOE, George Seweryniak Especially thank you to Kara Kruse, my mentor

18. Managed by UT-Battelle for the Department of Energy 18 Questions 18Managed by UT-Battelle for the Department of Energy If we know how fatty acid oxidation works then we will be able to figure out how to control obesity