Source: PURDUE UNIVERSITY submitted to
REGULATION OF LIPOGENESIS AND FATTY ACID OXIDATION IN THE PIG BY ADIPONECTIN
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0198089
Grant No.
2004-35206-14182
Project No.
IND051066G1
Proposal No.
2003-03269
Multistate No.
(N/A)
Program Code
42.0
Project Start Date
Dec 15, 2003
Project End Date
Dec 14, 2006
Grant Year
2004
Project Director
Spurlock, M. E.
Recipient Organization
PURDUE UNIVERSITY
(N/A)
WEST LAFAYETTE,IN 47907
Performing Department
ANIMAL SCIENCE
Non Technical Summary
The regulation of carcass fat accretion is directly related to the efficiency of feed utilization and consumer acceptance of meat products, both of which are factors that impact the profitability and sustainability of commercial pig production. In the current study, we are exploring the biological activity of adiponectin, a novel factor that is produced in the adipose tissue of pigs. The implications for adiponectin include its role as a regulator of body composition and feed utilization by adipose tissue and skeletal muscle. However, the role of adiponectin in adipocytes is not yet known, nor is known whether increasing blood concentrations of adiponectin will favor the utilization of dietary energy by skeletal muscle rather than fat tissue. This work is important because it will establish whether adiponectin is a major determinant of how dietary energy is used in growing pigs. If adiponectin exerts such a regulatory role in the pig, it will establish new targets for controlling nutrient partitioning between adipose tissue and skeletal muscle that may be exploited by genetic selection or prophylactic intervention. Such discoveries are essential to our over all objective of improving the efficiency and profitability of the pork industry.
Animal Health Component
10%
Research Effort Categories
Basic
90%
Applied
10%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
30235991010100%
Goals / Objectives
Adiponectin is an adipocyte-derived hormone that regulates energy metabolism. Previous findings have led us to the central hypothesis that adiponectin acts to control lipid accretion through autocrine and endocrine pathways, by which lipogenesis is attenuated and fatty acid oxidation is enhanced. In this project, we will use recombinant pig adiponectin and virally-mediated adiponectin expression to explore our central hypothesis. Using the pig and pig adipocyte as our model, our three objectives are to: (1) establish the extent to which adiponectin regulates the activity of 5'-AMP-activated protein kinase and acetyl Co-A carboxylase, and influences glucose transport in porcine adipocytes; (2) determine whether adiponectin enhances fatty acid oxidation in adipocytes through a PPARalpha-mediated mechanism that up regulates oxidative genes; (3) determine the extent to which prolonged hyper-adiponectinemia in growing pigs alters body composition and efficiency of gain.
Project Methods
Our approaches to accomplish our objectives is isolate primary pig adipocytes and perform lipogenesis and oxidation assays in vitro, in cells cultured in the presence or absence of recombinant pig adiponectin. In vivo, we will construct an adenovirus vector to deliver porcine adiponectin systemically. Thereafter, the regulation of key lipogenic and oxidative enzymes will be assessed by western blot analyses and activity assays. Glucose transport will be measured based on the transport of radiolabeled glucose in incubated adipocytes. To confirm the role of PPARalpha, we will incubate adipocytes with and without adiponectin, in the presence and absence of activators and inhibitors of the PPARalpha transcription factor. For the in vivo experiments, we will determine whether elevated concentrations of adiponectin alter the composition of gain (fat vs. lean) in growing pigs. Confirmation of a hyper-adiponectinemic state will be through semiquantitative western blot analysis of serum from pigs receiving the vector control or the adiponectin construct.

Progress 12/15/03 to 12/14/06

Outputs
Adiponectin is an adipocyte-derived hormone that regulates energy metabolism in vivo, and in muscle (i.e., myotube) cultures in vitro. In general, adiponectin promotes fatty acid oxidation and prevents an over accumulation of lipid in myofibers. Because the adiponectin receptors are also expressed in adipocytes, we anticipated that adiponectin would act directly on fat cells to suppress lipid accumulation. We have cloned and expressed porcine adiponectin. Our recent findings provide solid evidence that adiponectin suppresses lipid accumulation in pig adipocytes by suppressing the incorporation of glucose into lipid. We are currently determining the cellular mechanisms by which adiponectin acts on the fat cells to suppress lipogenesis, and results to date indicate that adiponectin activates the AMP-activated kinase, which subsequently phosphorylates a key lipogenic enzyme to deactivate it. In collaboration with Dr. Suresh Mittals laboratory, we have also conducted a small pilot study to use adenoviral vectors to over express adiponectin in the pig. These preliminary results indicate that circulating adiponectin concentrations are increased and that triglyceride concentrations are reduced. The results of our work provide essential information that will allow us to target specific tissues and signaling pathways within particular cell types to further establish the role of the adipocyte in the regulation of energy balance, and as a participant in the immune response. It is through these discoveries that novel strategies to improve the efficiency of animal production, and address animal well-being issues, will be developed.

Impacts
These discoveries offer novel strategies to improve the efficiency of animal production and address animal well-being issues.

Publications

  • No publications reported this period


Progress 10/01/03 to 09/30/04

Outputs
Adiponectin is an adipocyte-derived hormone that regulates energy metabolism in vivo, and in muscle (i.e., myotube) cultures in vitro. In general, adiponectin promotes fatty acid oxidation and prevents an over accumulation of lipid in myofibers. Because the adiponectin receptors are also expressed in adipocytes, we anticipated that adiponectin would act directly on fat cells to suppress lipid accumulation. We have cloned and expressed porcine adiponectin. Our recent findings provide solid evidence that adiponectin suppresses lipid accumulation in pig adipocytes by suppressing the incorporation of glucose into lipid. We are currently determining the cellular mechanisms by which adiponectin acts on the fat cells to suppress lipogenesis. In collaboration with Dr. Suresh Mittal's laboratory, we have also prepared adenovirus constructs to over express adiponectin in the pig in vivo so that growth and body composition experiments can be conducted. The results of our work provide essential information that will allow us to target specific tissues and signaling pathways within particular cell types to further establish the role of the adipocyte in the regulation of energy balance, and as a participant in the immune response.

Impacts
These discoveries offer novel strategies to improve the efficiency of animal production and address animal well-being issues.

Publications

  • Wulster-Radcliffe, M. C., J. A. Christian, J. Wang, and M. E. Spurlock. 2004. The anti-inflammatory actions of adiponectin include the regulation of IL-6 and IL-10, and a suppression of cell proliferation that is associated with increased caspase activity. Biochem. Biophys. Res. Comm.316(3):924-929
  • Ajuwon, K.M, S.K. Jacobi, J.L. Kuske, and M.E. Spurlock. 2004. Primary pig adipocytes respond directly to lipopolysaccharide and interferon-f by increasing the expression of interleukin-6 andinterleukin-15. Am J Physiol. 286(3):R547-53
  • Jacobi, S., K.M. Ajuwon, T.E. Weber, J.L. Kuske, C.J. Dyer, and M.E. Spurlock. 2004. Cloning and Expression of Porcine Adiponectin, and its Relationship to Adiposity, Lipogenesis, and the Acute Phase Response. J. Endocrinol. 182(1):133-44.
  • Weber, T. E., and M. E. Spurlock. 2004. Leptin alters antibody isotype in the pig in vivo, and prevents dexamethasone-induced down-regulation of the anti-apoptotic gene, bcl-xL, in peripheral blood monocytes in vitro. 2004. J. Anim. Sci. 82(6):1630-40.
  • Ajuwon, K. M., and M. E. Spurlock. 2004. Direct Regulation of Lipolysis and Lipogenesis by Interleukin-15 in Primary Pig Adipocytes. Am. J. Physiol.287(3):R608-11.