Nitric oxide (NO) is produced by endothelial NO synthase (eNOS) and plays a key role in maintaining vascular health and renal function. Chronic exposure to high glucose triggers oxidation of tetrahydrobiopterin (BH4), an essential eNOS cofactor, resulting in accumulation of dihydrobiopterin (BH2) in the vascular endothelium. During the initial period of Merit Award support, we discovered that BH2 binds eNOS with high avidity, replacing BH4 and switching the eNOS product from NO to superoxide. Studies suggest that BH2 binding to eNOS can initiate a pivotal feed-fonivard molecular cascade that drives oxidative stress and NO insufficiency in diabetic blood vessels, responsible for severe diabetic vascular complications that can lead to amputations, blindness, kidney failure and death. Research also demonstrates the efficacy of a novel pharmacological approach for disrupting the cascade of NO insufficiency and oxidative stress in diabetic blood vessels, utilizing agents that release NO via efficient reaction with superoxide (and/or derived oxidants). Remarkably, superoxide-dependent NO release is a property of the eNOS catalytic intermediate, N' -hydroxyarginine (NOMA), an endogenous molecule that circulates in blood at 5-10 pM. By concurrently scavenging oxidants and releasing NO, administered NOMA can selectively target NO delivery to vascular sites of oxidative stress, increasing BH4:BH2 and restoring eNOS coupling and NO production. Indeed, chronic NOMA treatment of genetically-diabetic db/db prevented development of endothelial dysfunction, hypertension and NO insufficiency that othenwise occurred in vehicle-treated controls. NOMA (or a related hydroxyguanidine) could fill a major unmet clinical need, by providing targeted therapy for diabetic vasculapathies as a first-in-class superoxide-dependent NO-releasing agent. The overall goal of studies proposed during this Merit Award extension period is to enhance our biochemical understanding of the role of NO in diabetes and extend our assessment of NOHA for potential therapy of diabetic vasculopathies. This will include evaluation of NOHA pharmacokinetics, metabolism, reaction mechanisms, effects on metabolism and therapeutic benefit in rodent models of diabetes-impaired wound healing, angiogenesis and limb blood flow insufficiency. Studies will rely on new research approaches and assays, established during the initial Merit Award period - including a powerful LC/MS/MS platform for global untargeted metabolite profiling (to survey expression changes in thousands of molecules, 50 - 1000 m/z) and a proteomic approach for discovering nitrated proteins and sites that result from uncoupled eNOS and may contribute to vasculopathy.
Insufficiency of endothelium-derived NO bioactivity is the basis for endothelial dysfunction in diabetic patients. Cardiovascular complications are the most common and devastating manifestation of diabetes, responsible for at least 77% of diabetic hospital admissions. Diminished NO is the apparent basis for diabetic vasculopathies that often result in amputations, blindness, kidney failure and death. This research seeks to evaluate a potential breakthrough pharmacological strategy and agent for therapy of diabetic vasculopthy.
|Hansler, Alex; Chen, Qiuying; Gray, Jason D et al. (2014) Untargeted metabolite profiling of murine embryos to reveal metabolic perturbations associated with neural tube closure defects. Birth Defects Res A Clin Mol Teratol 100:623-32|
|Diani-Moore, Silvia; Ma, Yuliang; Gross, Steven S et al. (2014) Increases in levels of epoxyeicosatrienoic and dihydroxyeicosatrienoic acids (EETs and DHETs) in liver and heart in vivo by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and in hepatic EET:DHET ratios by cotreatment with TCDD and the soluble epoxide hydrolas Drug Metab Dispos 42:294-300|
|Ismailoglu, Ismail; Chen, Qiuying; Popowski, Melissa et al. (2014) Huntingtin protein is essential for mitochondrial metabolism, bioenergetics and structure in murine embryonic stem cells. Dev Biol 391:230-40|
|Abbott, Geoffrey W; Tai, Kwok-Keung; Neverisky, Daniel L et al. (2014) KCNQ1, KCNE2, and Na+-coupled solute transporters form reciprocally regulating complexes that affect neuronal excitability. Sci Signal 7:ra22|
|Lu, Changyuan; Kavalier, Adam; Lukyanov, Eugene et al. (2013) S-sulfhydration/desulfhydration and S-nitrosylation/denitrosylation: a common paradigm for gasotransmitter signaling by H2S and NO. Methods 62:177-81|
|Deeb, Ruba S; Nuriel, Tal; Cheung, Cynthia et al. (2013) Characterization of a cellular denitrase activity that reverses nitration of cyclooxygenase. Am J Physiol Heart Circ Physiol 305:H687-98|
|Witherspoon, Mavee; Chen, Qiuying; Kopelovich, Levy et al. (2013) Unbiased metabolite profiling indicates that a diminished thymidine pool is the underlying mechanism of colon cancer chemoprevention by alpha-difluoromethylornithine. Cancer Discov 3:1072-81|
|Diani-Moore, Silvia; Ma, Yuliang; Labitzke, Erin et al. (2011) Discovery and biological characterization of 1-(1H-indol-3-yl)-9H-pyrido[3,4-b]indole as an aryl hydrocarbon receptor activator generated by photoactivation of tryptophan by sunlight. Chem Biol Interact 193:119-28|
|Nuriel, Tal; Hansler, Alex; Gross, Steven S (2011) Protein nitrotryptophan: formation, significance and identification. J Proteomics 74:2300-12|
|Zhou, Ping; Qian, Liping; Gallo, Eduardo F et al. (2011) The scavenger receptor CD36 contributes to the neurotoxicity of bone marrow-derived monocytes through peroxynitrite production. Neurobiol Dis 42:292-9|
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