Cardiovascular disease (CVD) is the leading cause of death in the US annually, accounting for nearly 1 in 3 deaths and over $500 billion in annual health care cost in the US. Platelet-mediated thrombosis is the primary underlying mechanism leading to cardiovascular life-threatening clinical events, such as stroke or myocardial infarction One form of platelet-mediated thrombosis is through the immune-complex activation of Fc?RIIa (a transmembrane receptor containing ITAM in the cytoplasmic tail). The activation of Fc?RIIa is responsible for immune-mediated thrombocytopenia and thrombosis, which can often lead to life-threatening cardiovascular related complications in patients who receive heparin or experience sepsis. Platelet 12-lipoxygenase (12-LOX) has been demonstrated to be an essential modulator of Fc?RIIa-mediated platelet activation; however, the underlying signaling mechanism by which 12-LOX regulates the Fc?RIIa signaling is still unclear. Understanding the signaling mechanisms by which 12-LOX regulates this pathway is a critical step in validating its role as a potential and effective anti-platelet target for the prevention of immune-mediated thrombotic events. For this proposal, I will aim to 1) elucidate the underlying mechanisms by which 12-LOX regulates the Fc?RIIa-mediated activation in platelets. The role of 12-hydroxyeicosatetraenoic acid (12-HETE), the predominant 12-LOX oxidized lipid, and potential protein binding partners of 12-LOX will be investigated and identified in the Fc?RIIa signaling pathway. These studies will provide valuable and deeper insights in the biochemical roles of 12-LOX in the Fc?RIIa-mediated platelet activation pathway.
Aim will 2) Characterize the role of 12-LOX in vivo by utilizing transgenic mice expressing humanized Fc?RIIa and deficient in 12-LOX (hFcR/ALOX12-/-) compared to the normal 12-LOX model (hFcR/ALOX12+/+). The in vivo approaches will aid in determining whether 12-LOX proves to be an efficient target in treating and limiting immune-mediated thrombocytopenia and as well preventing thrombosis. Elucidating the underlying mechanisms by which 12- LOX and its oxylipin regulate Fc?RIIa-mediated platelet function is crucial in order to accelerate the rational design of novel therapeutics for immune-mediated disorders involving incidence of thrombotic occlusion.

Public Health Relevance

12?Lipoxygenase potentiates platelet reactivity, leading to unwanted thrombosis and blood clot formation. Additionally, 12?lipoxpoygenase has been proposed to be a viable target in regulating Fc?RIIa-mediated platelet activation and thrombosis. In order to validate 12?LOX As a therapeutic target, the signaling mechanisms by which 12-LOX impinge on the Fc?RIIa signaling pathway must be elucidated.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31HL129481-03
Application #
9330225
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Chang, Henry
Project Start
2015-09-01
Project End
2018-02-28
Budget Start
2017-09-01
Budget End
2018-02-28
Support Year
3
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Type
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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Yeung, Jennifer; Li, Wenjie; Holinstat, Michael (2018) Platelet Signaling and Disease: Targeted Therapy for Thrombosis and Other Related Diseases. Pharmacol Rev 70:526-548
Adili, Reheman; Tourdot, Benjamin E; Mast, Katherine et al. (2017) First Selective 12-LOX Inhibitor, ML355, Impairs Thrombus Formation and Vessel Occlusion In Vivo With Minimal Effects on Hemostasis. Arterioscler Thromb Vasc Biol 37:1828-1839
Yeung, Jennifer; Hawley, Megan; Holinstat, Michael (2017) The expansive role of oxylipins on platelet biology. J Mol Med (Berl) 95:575-588
Yeung, Jennifer; Holinstat, Michael (2017) Who is the real 12-HETrE? Prostaglandins Other Lipid Mediat 132:25-30
Yeung, Jennifer; Tourdot, Benjamin E; Adili, Reheman et al. (2016) 12(S)-HETrE, a 12-Lipoxygenase Oxylipin of Dihomo-?-Linolenic Acid, Inhibits Thrombosis via G?s Signaling in Platelets. Arterioscler Thromb Vasc Biol 36:2068-77