Regions of the circulation, such as the carotid bulb, the proximal coronary arteries and the distal aorta are exposed to disturbed, often oscillatory flow and are predisposed to development of atherosclerosis. There is currently no therapy to prevent lesion development at these sites. Tetrahydrobiopterin (BH4) is a critical cofactor for the nitric oxide synthase (NOS) enzymes and in its absence, the NOS enzymes become uncoupled, so that they produce superoxide (O2-) rather than NO. Our laboratory has discovered a new mechanism by which endothelial cells modulate BH4 levels in response to shear. We found that laminar shear stimulates BH4 levels by 30-fold, and increases the activity of GTP cyclohydrolase-1 (GTPCH-1), the rate-limiting enzyme for BH4 production, by a similar extent. Shear stress dissociates GTPCH-1 from its feedback regulatory protein (GFRP), and this allows phosphorylation of GTPCH-1 on serine 81 (serine 72 in the mouse) by casein kinase alpha prime. In contrast, oscillatory shear stress does not dissociate GFRP and GTPCH-1, and does not cause GTPCH-1 phosphorylation, causing BH4 levels to be insufficient. This reduces NO production and increases O2"""""""" levels, and markedly enhances atherosclerotic lesion development in a mouse model with disturbed carotid flows. We therefore propose that GTPCH-1 phosphorylation represents a critical switch that alters endothelial cell phenotype, promotes oxidative injury, reduces NO production and predisposes to atherosclerosis. To test this hypothesis in vivo, we have successfully targeted knock-in of both an aspartate (to mimic phosphorylation) and an alanine (to prevent phosphorylation) in murine embryonic stem cells.
In aims 1, we will to study mice with the aspartate knock-in (KI[GCH/S72D] mice) to determine if maintaining GTPCH-1 activation prevents atherosclerosis and preserves NO function.
In aim 2, we will study mice in which GTPCH-1 cannot be activated by shear ( K I [GCH/S72A] mice), hypothesize that these animals will have enhanced atherosclerosis lesion. In the final aim, we plan to continue studies to discover new molecules that cause dissociation of GFRP and GTPCH-1. To accomplish this, we have developed a high-throughput screening assay and have already used this to screen 34,000 molecules. We have promising preliminary data to show that this approach will allow discovery of genes that can increase endothelial cell BH4 levels. We propose that agents discovered using this approach will provide of novel approach for prevention of atherosclerosis at sites of disturbed flow in vivo.

Public Health Relevance

While strategies such as lipid lowering and risk factor modification have proven effective in treatment of atherosclerosis, there are currently no specific therapies to prevent atherosclerosis in regions of the circulation with disturbed blood flow. In this project, we will test the hypothesis that a major cause of atherosclerosis at these sites is deficient tetrahydrobiopterin, and wilt attempt to discover new treatment strategies for prevention of atherosclerosis at these sites.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Vanderbilt University Medical Center
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Salisbury-Ruf, Christi T; Bertram, Clinton C; Vergeade, Aurelia et al. (2018) Bid maintains mitochondrial cristae structure and function and protects against cardiac disease in an integrative genomics study. Elife 7:
Foss, Jason D; Kirabo, Annet; Harrison, David G (2017) Do high-salt microenvironments drive hypertensive inflammation? Am J Physiol Regul Integr Comp Physiol 312:R1-R4
Kong, Deping; Li, Juanjuan; Shen, Yujun et al. (2017) Niacin Promotes Cardiac Healing after Myocardial Infarction through Activation of the Myeloid Prostaglandin D2 Receptor Subtype 1. J Pharmacol Exp Ther 360:435-444
Teder, Tarvi; Boeglin, William E; Brash, Alan R (2017) Oxidation of C18 Hydroxy-Polyunsaturated Fatty Acids to Epoxide or Ketone by Catalase-Related Hemoproteins Activated with Iodosylbenzene. Lipids 52:587-597
Plewes, Katherine; Kingston, Hugh W F; Ghose, Aniruddha et al. (2017) Cell-free hemoglobin mediated oxidative stress is associated with acute kidney injury and renal replacement therapy in severe falciparum malaria: an observational study. BMC Infect Dis 17:313
Harrison, D G; Guzik, Tomasz J (2016) Macrophages come to mind as keys to cognitive decline. J Clin Invest 126:4393-4395
Gamble-George, Joyonna Carrie; Baldi, Rita; Halladay, Lindsay et al. (2016) Cyclooxygenase-2 inhibition reduces stress-induced affective pathology. Elife 5:
Kudalkar, Shalley N; Kingsley, Philip J; Marnett, Lawrence J (2016) Assay of Endocannabinoid Oxidation by Cyclooxygenase-2. Methods Mol Biol 1412:205-15
Wu, Jing; Montaniel, Kim Ramil C; Saleh, Mohamed A et al. (2016) Origin of Matrix-Producing Cells That Contribute to Aortic Fibrosis in Hypertension. Hypertension 67:461-8
Montaniel, Kim Ramil C; Harrison, David G (2016) Is Hypertension a Bone Marrow Disease? Circulation 134:1369-1372

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