The resident mitochondrial protein kinases (mPKs) comprising pyruvate dehydrogenase kinases (PDKs), and branched-chain 1-ketoacid dehydrogenase kinase (BCK) are the molecular switches that control carbohydrate and branched-chain amino acid degradation. Mitochondrial PDKs (isoforms 1, 2, 3 and 4) down-regulate activity of the mitochondrial pyruvate dehydrogenase complex by reversible phosphorylation, in response to hormonal and nutritional stimuli. Certain PDK isoforms are over-expressed in disease states such as type 2 diabetes, obesity and cancer, resulting in decreased glucose oxidation. Towards understanding the structure and function of these PDKs, the P.I.'s laboratory has solved the crystal structures for three (PDK1, PDK3 and PDK4) of the four PDK isoforms and various PDK-inhibitor/activator complexes. Based on these advances, the P.I. proposes to continue investigation into the structure, function and regulation of mammalian PDKs.
The Specific Aims are: 1) To decipher the allosteric mechanisms by which the L2 domain and the synthetic ligands modulate PDK activities;2) To offer biochemical and structural basis for the hyperactivity of PDK4 and to identify the E1p substrate-binding site in this kinase isoform;3) To isolate a new generation of small-molecule inhibitors that are specific for PDK4 by high-through-put screening and characterize these novel inhibitors both in vitro and in cell culture. Standard methods including X-ray crystallography, isothermal titration calorimetry, kinase activity assays and the high-through-put screening method will be employed to achieve these Specific Aims. The availability of PDK4-specific inhibitors will foster new strategies to mitigate defective glucose oxidation in obesity and type 2 diabetes.

Public Health Relevance

The mitochondrial protein kinases to be studied in this project are molecular switches that control carbohydrate and amino acid degradation in the liver and skeletal muscle. Aberrant functions of these protein kinases have been implicated in obesity and type 2 diabetes. Understanding the structure and function of pyruvate dehydrogenase kinase (PDK) isoforms and the development of PDK isoform #4-specific inhibitors will foster new strategies to mitigate defective glucose oxidation in these human diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK062306-09
Application #
8268354
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Sechi, Salvatore
Project Start
2002-07-01
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
9
Fiscal Year
2012
Total Cost
$334,680
Indirect Cost
$121,508
Name
University of Texas Sw Medical Center Dallas
Department
Biochemistry
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
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