Cardiac hypertrophic remodeling underlies a large component of the morbidity and mortality of heart disease. It affects nearly 10% of the world's population given the high prevalence of hypertension and hypertrophy that evolves with it. Cyclic guanosine-3', 5'-monophosphate (cGMP) is an intracellular second messenger which controls diverse cell physiology. Accumulating evidence shows that enhanced synthesis of cGMP by nitric oxide or natriuretic peptides negatively regulate cardiac hypertrophy development. We recently found that blocking cGMP degradation with phospho- diesterase5A (PDE5A) inhibitor have potent anti-hypertrophic and anti-remodeling effects. One major downstream mediator of cGMP is cGMP-dependent protein kinase (cGK). It remains unclear how cGMP and its downstream cGK regulate intra-cellular signaling network, resulting in such physiological impact on the heart. PDE5A inhibitors are currently widely used to treat erectile dysfunction and pulmonary hypertension. Reports from us and others supporting cardiac benefits from cGMP enhancement by PDE5A inhibitors have raised substantial interest for these drugs in treatment of human heart disease. To clarify the underlying mechanism of this signaling takes on more prominence now that the NIH is expected to initiate a clinical trial of PDE5A inhibitor in heart failure patients. Our preliminary data suggest that cGMP- activated cGK type I1 (cGKI1) targets two different molecules to exert beneficial effects over stressed or diseased heart, depending on its intracellular location at different stages of cardiac remodeling. cGKI1 blunts Gq signaling by activating its inhibitory protein named regulator of G-protein coupled signaling 2 (RGS2) at the sarcolemmal membrane in the early phase of hypertrophy development, whereas in the late phase (failure), it up-regulates PGC-11 (peroxisome proliferators-activated receptor 3 coactivator 1-1), a master regulator of mitochondrial biogenesis and function possibly in the nucleus. The research in this proposal aims to provide critical information on the mechanisms of this regulation in two aims by utilizing animals deficient in RGS2 (conventional and inducible conditional) and animals harboring mutant cGKI1 in which critical protein- protein interaction site (leucine zipper motif) is disrupted.
The first aim will examine the cardio- protective mechanism of GKI1 in the early hypertrophy development phase.
The second aim will examine the role and the mechanism of PGC-11 regulation by cGKI1, and its impact on mitochondrial biogenesis/ function in the late phase of cardiac failure. The successful completion of these studies will greatly expand our understanding of the role for cGMP signaling in diseased hearts, and inform clinical trials testing cGMP signaling-enhancing drugs such as PDE5A inhibitors for treating heart disease.

Public Health Relevance

Nearly 10% of the world's population develops cardiac hypertrophy which increases their risk of suffering from heart disease, and sudden death. We discovered that cardiac hypertrophy/ remodeling is ameliorated by enhancing intrinsic cGMP pathway with sildenafil (Viagra), the drug currently widely used for treating erectile dysfunction. This project will clarify the underlying mechanisms for this beneficial impact from enhanced cGMP signaling pathway in the heart, focusing on a major downstream molecule and its interaction with other key regulators.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Adhikari, Bishow B
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Johns Hopkins University
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Zhu, Guangshuo; Groneberg, Dieter; Sikka, Gautam et al. (2015) Soluble guanylate cyclase is required for systemic vasodilation but not positive inotropy induced by nitroxyl in the mouse. Hypertension 65:385-92
Lee, Dong I; Zhu, Guangshuo; Sasaki, Takashi et al. (2015) Phosphodiesterase 9A controls nitric-oxide-independent cGMP and hypertrophic heart disease. Nature 519:472-6
Nakamura, Taishi; Ranek, Mark J; Lee, Dong I et al. (2015) Prevention of PKG1? oxidation augments cardioprotection in the stressed heart. J Clin Invest 125:2468-72
Sasaki, Hideyuki; Nagayama, Takahiro; Blanton, Robert M et al. (2014) PDE5 inhibitor efficacy is estrogen dependent in female heart disease. J Clin Invest 124:2464-71
Rainer, Peter P; Hao, Scarlett; Vanhoutte, Davy et al. (2014) Cardiomyocyte-specific transforming growth factor ? suppression blocks neutrophil infiltration, augments multiple cytoprotective cascades, and reduces early mortality after myocardial infarction. Circ Res 114:1246-57
Rowell, Janelle; Koitabashi, Norimichi; Kass, David A et al. (2014) Dynamic gene expression patterns in animal models of early and late heart failure reveal biphasic-bidirectional transcriptional activation of signaling pathways. Physiol Genomics 46:779-87
Blanton, Robert M; Takimoto, Eiki; Aronovitz, Mark et al. (2013) Mutation of the protein kinase I alpha leucine zipper domain produces hypertension and progressive left ventricular hypertrophy: a novel mouse model of age-dependent hypertensive heart disease. J Gerontol A Biol Sci Med Sci 68:1351-5
Zhang, Manling; Takimoto, Eiki; Lee, Dong-ik et al. (2012) Pathological cardiac hypertrophy alters intracellular targeting of phosphodiesterase type 5 from nitric oxide synthase-3 to natriuretic peptide signaling. Circulation 126:942-51
Lee, Dong I; Kass, David A (2012) Phosphodiesterases and cyclic GMP regulation in heart muscle. Physiology (Bethesda) 27:248-58
Tsai, Emily J; Liu, Yuchuan; Koitabashi, Norimichi et al. (2012) Pressure-overload-induced subcellular relocalization/oxidation of soluble guanylyl cyclase in the heart modulates enzyme stimulation. Circ Res 110:295-303

Showing the most recent 10 out of 18 publications