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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Wang, Pingyuan; Liu, Zhiqing; Chen, Haiying et al. (2017) Exchange proteins directly activated by cAMP (EPACs): Emerging therapeutic targets. Bioorg Med Chem Lett 27:1633-1639
Liu, Zhiqing; Zhu, Yingmin; Chen, Haiying et al. (2017) Structure-activity relationships of 2-substituted phenyl-N-phenyl-2-oxoacetohydrazonoyl cyanides as novel antagonists of exchange proteins directly activated by cAMP (EPACs). Bioorg Med Chem Lett 27:5163-5166
Ye, Na; Zhu, Yingmin; Liu, Zhiqing et al. (2017) Identification of novel 2-(benzo[d]isoxazol-3-yl)-2-oxo-N-phenylacetohydrazonoyl cyanide analoguesas potent EPAC antagonists. Eur J Med Chem 134:62-71
Zhu, Yingmin; Mei, Fang; Luo, Pei et al. (2017) A cell-based, quantitative and isoform-specific assay for exchange proteins directly activated by cAMP. Sci Rep 7:6200
Wild, Christopher T; Zhu, Yingmin; Na, Ye et al. (2016) Functionalized N,N-Diphenylamines as Potent and Selective EPAC2 Inhibitors. ACS Med Chem Lett 7:460-4
Almahariq, Muayad; Mei, Fang C; Cheng, Xiaodong (2016) The pleiotropic role of exchange protein directly activated by cAMP 1 (EPAC1) in cancer: implications for therapeutic intervention. Acta Biochim Biophys Sin (Shanghai) 48:75-81
Hu, Yaohua; Robichaux 3rd, William G; Mei, Fang C et al. (2016) Role of Exchange Protein Directly Activated by Cyclic AMP Isoform 1 in Energy Homeostasis: Regulation of Leptin Expression and Secretion in White Adipose Tissue. Mol Cell Biol 36:2440-50
Wang, Hui; Robichaux, William G; Wang, Ziqing et al. (2016) Inhibition of Epac1 suppresses mitochondrial fission and reduces neointima formation induced by vascular injury. Sci Rep 6:36552

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