cAMP-mediated signaling regulates a myriad of important biological processes under physiological conditions and disease states, including diabetes, heart failure and cancer. In eukaryotic cells, the effects of cAMP are mediated by two ubiquitously expressed intracellular cAMP receptors, the classic protein kinase A/cAMP-dependent protein kinase (PKA/cAPK) and the recently discovered exchange protein directly activated by cAMP/cAMP-regulated guanine nucleotide exchange factor (Epac/cAMP-GEF). The existence of two ubiquitously expressed cAMP effectors provides a mechanism for a more precise and integrated control of the cAMP signaling pathways in a spatial and temporal manner. However, little is known about the mechanism of Epac activation. The objective of this proposal is to fill the gap in our current knowledge by mapping the conformational changes associated with Epac activation. Specifically, we have planned experiments with the following Specific Aims: 1) To determine the specific residues important for Epac activation by site-directed mutagenesis;2) to delineate the conformational changes associated with cAMP binding and Epac activation and to determine the protein interface between Epac and it's downstream effector, Rap1, using enhanced deuterium exchange-mass spectrometry (DXMS) and small-angle X-ray scattering;and 3) to solve the crystal structure of Epac2-cAMP using X-ray crystallography. The long-term goals of our research are to understand the physiological functions and mechanisms of Epac regulation. Accomplishing the proposed research in this application will significantly move the field forward towards these goals. Furthermore, the medical and pharmacological implications of this research program are also far-reaching. A better understanding of cAMP- mediated signal transduction could potentially lead to the identification of novel mechanism-based therapeutic strategies specifically targeting the cAMP-signaling components.

Public Health Relevance

Cylic AMP-mediated signaling regulates a myriad of important biological processes under both physiological conditions and disease states, including diabetes, heart failure and cancer. Components of the cAMP-signaling cascade have been implicated in abnormal cell growth and drug actions and successfully targeted for diagnosis and chemotherapy of cancer and other diseases. A better understanding of cAMP- mediated signal transduction could potentially lead to the identification of novel drug targets and the development of new or improved therapeutic agents.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM066170-09
Application #
8197449
Study Section
Molecular and Integrative Signal Transduction Study Section (MIST)
Program Officer
Gerratana, Barbara
Project Start
2003-05-01
Project End
2013-11-30
Budget Start
2011-12-01
Budget End
2012-11-30
Support Year
9
Fiscal Year
2012
Total Cost
$344,608
Indirect Cost
$96,012
Name
University of Texas Medical Br Galveston
Department
Pharmacology
Type
Schools of Medicine
DUNS #
800771149
City
Galveston
State
TX
Country
United States
Zip Code
77555
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Tao, Xinrong; Mei, Feng; Agrawal, Anurodh et al. (2014) Blocking of exchange proteins directly activated by cAMP leads to reduced replication of Middle East respiratory syndrome coronavirus. J Virol 88:3902-10
Chen, Haijun; Wild, Christopher; Zhou, Xiaobin et al. (2014) Recent advances in the discovery of small molecules targeting exchange proteins directly activated by cAMP (EPAC). J Med Chem 57:3651-65
Chen, Haijun; Ding, Chunyong; Wild, Christopher et al. (2013) Efficient Synthesis of ESI-09, A Novel Non-cyclic Nucleotide EPAC Antagonist. Tetrahedron Lett 54:1546-1549
Almahariq, Muayad; Tsalkova, Tamara; Mei, Fang C et al. (2013) A novel EPAC-specific inhibitor suppresses pancreatic cancer cell migration and invasion. Mol Pharmacol 83:122-8
Yan, Jingbo; Mei, Fang C; Cheng, Hongqiang et al. (2013) Enhanced leptin sensitivity, reduced adiposity, and improved glucose homeostasis in mice lacking exchange protein directly activated by cyclic AMP isoform 1. Mol Cell Biol 33:918-26
Chepurny, Oleg G; Bertinetti, Daniela; Diskar, Mandy et al. (2013) Stimulation of proglucagon gene expression by human GPR119 in enteroendocrine L-cell line GLUTag. Mol Endocrinol 27:1267-82
Chen, Haijun; Tsalkova, Tamara; Chepurny, Oleg G et al. (2013) Identification and characterization of small molecules as potent and specific EPAC2 antagonists. J Med Chem 56:952-62
Zhang, Adrianna P P; Bornholdt, Zachary A; Liu, Tong et al. (2012) The ebola virus interferon antagonist VP24 directly binds STAT1 and has a novel, pyramidal fold. PLoS Pathog 8:e1002550
Lu, Weiya D; Liu, Tong; Li, Sheng et al. (2012) The prohormone proenkephalin possesses differential conformational features of subdomains revealed by rapid H-D exchange mass spectrometry. Protein Sci 21:178-87

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