Cyclic nucleotide phosphodiesterases (PDEs) control cellular concentration of "second messengers" cAMP and cGMP that modulate many metabolic processes. Human genome encodes 21 PDE genes that are categorized into 11 families and express over 100 isoforms of proteins via RNA splicing. Selective inhibitors of PDEs have been studied as therapeutic agents for various human diseases. An example is PDE5-selective inhibitor sildenafil (Viagra) that is a drug for treatment of erectile dysfunction and pulmonary hypertension. The studies of our last grant proposal have led to publications of 14 original research papers, and provided insight into the mechanisms of substrate specificity and inhibitor selectivity of PDEs. However, no structures of full-length or fragments with both regulatory and catalytic domains are available so that it remains unknown how the PDE catalysis is regulated by their regulatory domains. It is also a puzzle how PDEs cross-talk to proteins in other signaling pathways. This proposal aims at understanding regulation of PDE activities by their regulatory domains, PDE interaction with other proteins, and PDE inhibitor discovery.
The specific aims i nclude: (1) structural and biochemical studies of the near-full length PDE5A1 and its complexes with substrate and inhibitors, (2) structures of PDE8A and its complexes with inhibitors and with the binding protein I?B?, (3) structural and kinetic studies on PDE1A in complex with calmodulin, and (4) structure-based discovery of PDE4 inhibitors for treatment of inflammatory diseases.
Specific aims I, II, and III will not only reveal the structural information of near full-length PDE5, PDE8 and PDE1, but also provide insight into the catalytic mechanisms of these PDE families. The complex structures of PDE1-calmodulin and PDE8-I?B? will shed light on the potential roles of the PDE families in the signaling pathways.
Specific aim I V may lead to discovery of a new category of PDE4 inhibitors for treatment of human diseases.

Public Health Relevance

Phosphodiesterases (PDEs) are sole enzymes degrading cellular second messengers cAMP and cGMP that play important roles in physiological processes. This proposal aims at (1) structural and biochemical studies of near-full length PDE1, 5, and 8 and their interactions with calmodulin and IkB and (2) structure-based discovery of PDE4 selective inhibitors. These studies will not only provide insight into the regulation of PDE catalysis and interactions with proteins in other signaling pathways, but also lead to discovery of PDE4 inhibitors for treatment of human diseases.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Macromolecular Structure and Function B Study Section (MSFB)
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Flicker, Paula F
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University of North Carolina Chapel Hill
Schools of Medicine
Chapel Hill
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Shang, Na-Na; Shao, Yong-Xian; Cai, Ying-Hong et al. (2014) Discovery of 3-(4-hydroxybenzyl)-1-(thiophen-2-yl)chromeno[2,3-c]pyrrol-9(2H)-one as a phosphodiesterase-5 inhibitor and its complex crystal structure. Biochem Pharmacol 89:86-98
Tian, Yuanyuan; Cui, Wenjun; Huang, Manna et al. (2014) Dual specificity and novel structural folding of yeast phosphodiesterase-1 for hydrolysis of second messengers cyclic adenosine and guanosine 3',5'-monophosphate. Biochemistry 53:4938-45
Jansen, Chimed; Wang, Huanchen; Kooistra, Albert J et al. (2013) Discovery of novel Trypanosoma brucei phosphodiesterase B1 inhibitors by virtual screening against the unliganded TbrPDEB1 crystal structure. J Med Chem 56:2087-96
Wang, Huanchen; Kunz, Stefan; Chen, Gong et al. (2012) Biological and structural characterization of Trypanosoma cruzi phosphodiesterase C and Implications for design of parasite selective inhibitors. J Biol Chem 287:11788-97
Francis, Sharron H; Sekhar, Konjeti R; Ke, Hengming et al. (2011) Inhibition of cyclic nucleotide phosphodiesterases by methylxanthines and related compounds. Handb Exp Pharmacol :93-133
Hou, Jing; Xu, Jie; Liu, Ming et al. (2011) Structural asymmetry of phosphodiesterase-9, potential protonation of a glutamic acid, and role of the invariant glutamine. PLoS One 6:e18092
Seebeck, Thomas; Sterk, Geert Jan; Ke, Hengming (2011) Phosphodiesterase inhibitors as a new generation of antiprotozoan drugs: exploiting the benefit of enzymes that are highly conserved between host and parasite. Future Med Chem 3:1289-306
Zhang, Jun; Sapienza, Paul J; Ke, Hengming et al. (2010) Crystallographic and nuclear magnetic resonance evaluation of the impact of peptide binding to the second PDZ domain of protein tyrosine phosphatase 1E. Biochemistry 49:9280-91
Wang, Huanchen; Luo, Xuan; Ye, Mengchun et al. (2010) Insight into binding of phosphodiesterase-9A selective inhibitors by crystal structures and mutagenesis. J Med Chem 53:1726-31
Wang, Huanchen; Robinson, Howard; Ke, Hengming (2010) Conformation changes, N-terminal involvement, and cGMP signal relay in the phosphodiesterase-5 GAF domain. J Biol Chem 285:38149-56

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