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Synthesis of indole derived protease-activated receptor 4 antagonists and characterization in human platelets.

ABSTRACT: Protease activated receptor-4 (PAR4) is one of the thrombin receptors on human platelets and is a potential target for the management of thrombotic disorders. We sought to develop potent, selective, and novel PAR4 antagonists to test the role of PAR4 in thrombosis and hemostasis. Development of an expedient three-step synthetic route to access a novel series of indole-based PAR4 antagonists also necessitated the development of a platelet based high-throughput screening assay. Screening and subsequent structure activity relationship analysis yielded several selective PAR4 antagonists as well as possible new scaffolds for future antagonist development.

SUBMITTER: Young SE

PROVIDER: S-EPMC3679140 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Synthesis of indole derived protease-activated receptor 4 antagonists and characterization in human platelets.

Young Summer E SE Duvernay Matthew T MT Schulte Michael L ML Lindsley Craig W CW Hamm Heidi E HE

PloS one 20130611 6

Protease activated receptor-4 (PAR4) is one of the thrombin receptors on human platelets and is a potential target for the management of thrombotic disorders. We sought to develop potent, selective, and novel PAR4 antagonists to test the role of PAR4 in thrombosis and hemostasis. Development of an expedient three-step synthetic route to access a novel series of indole-based PAR4 antagonists also necessitated the development of a platelet based high-throughput screening assay. Screening and subse ...[more]

PMID: 23776495

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Protease-activated receptor signaling in platelets activates cytosolic phospholipase A2? differently for cyclooxygenase-1 and 12-lipoxygenase catalysis.

Project description:The rate-limiting step in the biosynthesis of thromboxane A(2) (TxA(2)) and 12-hydroxyeicosatetraenoic acid (12-HETE) by platelets is activation of cytosolic phospholipase A(2?) (cPLA(2?)), which releases arachidonic acid, which is the substrate for cyclooxygenase-1 (COX-1) and 12-lipoxygenase. We evaluated signaling via the human platelet thrombin receptors, protease-activated receptor (PAR) 1 and PAR4, to the activation of cPLA(2?), which provides a substrate for the biosynthesis of TxA(2) and 12-HETE.Stimulating washed human platelets resulted in delayed biosynthesis of 12-HETE, which continues after maximal formation of TxA(2) is completed, suggesting that 12-HETE is not formed by the same pool of arachidonic acid that provides a substrate to COX-1. PAR1-induced formation of TxA(2) was inhibited by the phosphatidylinositol kinase inhibitor LY294002, whereas this inhibitor did not block 12-HETE biosynthesis. Both 1-butanol and propranolol also blocked TxA(2) biosynthesis but did not inhibit 12-HETE formation.The concerted evidence indicates that the platelet thrombin receptors signal activation of cPLA(2?) coupled to COX-1 by a pathway different from that signaling activation of the cPLA(2?) coupled to 12-lipoxygenase.

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Thrombin-induced reactive oxygen species generation in platelets: A novel role for protease-activated receptor 4 and GPIbα.

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| S-EPMC4656914 | biostudies-literature

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