The long-term goal of this project is to understand how prostanoid receptors mediate human physiopathological vascular and hemodynamic processes, including hemostasis, thrombosis, and inflammation. Prostanoids, including thromboxane A2 (TXA2), prostacyclin 12 (PGI2) and prostaglandin D2 (PGD2), E2 (PGE2) and F2 (PGF2) are synthesized by vascular smooth muscle, endothelium, and other tissues. TXA2 is a potent stimulator of platelet aggregation and a smooth muscle constrictor. PGI2 actions are essentially opposite to those of TXA2. PGE2 plays diverse/opposite functions as a vasodilator or vasoconstrictor based on the mediations of the subtype receptors. TXA2 and PGI2 are also mediated by their receptors. All the receptors belong to the G protein-coupled receptor family, with seven transmembrane domains, and are coupled to different signaling. The structure and function relationships of the TXA2 receptor (TP), the PGI2 receptor (IP) and four subtype PGE2 receptors (EP) are poorly defined, with little structural information on how the prostanoids recognize their receptors and signaling through G proteins specifically. The diverse receptor-mediated actions of TXA2, PGI2, and PGE2 have led us to hypothesize that the receptors have distinct 3D structures in their extracellular ligand recognition sites, and in their intracellular G protein-coupled sites. Recently, we have partially characterized the ligand-binding pockets in the extracellular domains, and parts of the intracellular G protein coupling domains of the TP and IP receptors. Further characterization of the specific ligand recognition and G protein coupling sites of the TP, IP, and a typical EP receptor should reveal their differences. The following specific aims will use recombinant receptor mutants, synthetic peptides, circular dichroism and 2D nuclear magnetic resonance spectroscopy to: 1. Identify the segments and key residues comprising the TP receptor agonist recognition pocket for comparison with the antagonist recognition pocket; 2. Determine the solution conformation of the extracellular domains of the IP receptor and define the segments and key residues making up the ligand recognition pocket; 3. Determine the solution conformation of the extracellular domains in the human EP3 receptor, and identify the residues making up its specific ligand recognition pocket for comparison with those of the TP and IP receptors; 4. Determine the solution conformation of segments comprising the intracellular domains.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Hemostasis and Thrombosis Study Section (HT)
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Goldman, Stephen
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University of Texas Health Science Center Houston
Internal Medicine/Medicine
Schools of Medicine
United States
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Ling, Qing-Lan; Mohite, Anita J; Murdoch, Emma et al. (2018) Creating a mouse model resistant to induced ischemic stroke and cardiovascular damage. Sci Rep 8:1653
Akasaka, Hironari; Thaliachery, Natasha; Zheng, Xianghai et al. (2017) The key residue within the second extracellular loop of human EP3 involved in selectively turning down PGE2- and retaining PGE1-mediated signaling in live cells. Arch Biochem Biophys 616:20-29
Akasaka, Hironari; Ruan, Ke-He (2016) Identification of the two-phase mechanism of arachidonic acid regulating inflammatory prostaglandin E2 biosynthesis by targeting COX-2 and mPGES-1. Arch Biochem Biophys 603:29-37
Akasaka, Hironari; So, Shui-Ping; Ruan, Ke-He (2015) Relationship of the Topological Distances and Activities between mPGES-1 and COX-2 versus COX-1: Implications of the Different Post-Translational Endoplasmic Reticulum Organizations of COX-1 and COX-2. Biochemistry 54:3707-15
Vollert, Craig; Ohia, Odochi; Akasaka, Hironari et al. (2014) Elevated prostacyclin biosynthesis in mice impacts memory and anxiety-like behavior. Behav Brain Res 258:138-44
Ruan, Ke-He; Mohite, Anita J; So, Shui-Ping (2013) Resistant to thrombosis, induced stroke and heart arrest by incorporation of a single gene of PGI2-synthesizing COX-1-PGIS in vivo: Implication against human heart disease. Int J Cardiol 168:2960-1
Lin, Haocheng; Yuan, Jiuhong; Ruan, Ke-He et al. (2013) COX-2-10aa-PGIS gene therapy improves erectile function in rats after cavernous nerve injury. J Sex Med 10:1476-87
Chillar, Annirudha; So, Shui-Ping; Ruan, Cheng-Huai et al. (2011) A profile of NSAID-targeted arachidonic acid metabolisms in human embryonic stem cells (hESCs): implication of the negative effects of NSAIDs on heart tissue regeneration. Int J Cardiol 150:253-9
Ruan, Cheng-Huai; So, Shui-Ping; Ruan, Ke-He (2011) Inducible COX-2 dominates over COX-1 in prostacyclin biosynthesis: mechanisms of COX-2 inhibitor risk to heart disease. Life Sci 88:24-30
Mohite, Anita; Chillar, Annirudha; So, Shui-Ping et al. (2011) Novel mechanism of the vascular protector prostacyclin: regulating microRNA expression. Biochemistry 50:1691-9

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