There is an emerging appreciation that heme proteins such as myoglobin and hemoglobin catalyze the metabolism of nitric oxide (NO) and nitrite, and thereby modulate cell and tissue responses to hypoxia. Over the last five years our group has published biochemical and physiological studies that suggest a novel function for hemoglobin as a nitrite reductase that generates NO under physiological and pathological hypoxia, suggesting that myoglobin, the other major heme globin, may also possess a capability to mediate the metabolism of oxides of nitrogen in a manner influenced by oxygen tension. Analogous to the bacterial nitrite reductases, a concerted proton and electron transfer reaction to nitrite reduces the anion to NO. We have also discovered a novel nitrite anhydrase activity that converts two nitrite molecules into the highly diffusible, nitrosating molecule N2O3, allowing efficient NO signaling in a heme rich environment. In the current research proposal, the NO/ N2O3 signaling pathways will be explored in myoglobin, with special focus on an ability to regulate cellular responses to hypoxic and ischemic stress by a) modulating cellular metabolism via the regulation of mitochondrial electron transfer reactions and b) activating net cytoprotective cell signaling reactions after ischemia-reperfusion injury. These concepts will be addressed by testing the hypothesis that myoglobin-mediated nitrite metabolism regulates hypoxic NO signaling and promotes NO bioavailability in the heart. More specifically, using mutant myoglobin proteins in in vitro biochemical and cell culture systems as well as an in vivo model of myocardial infarction, we aim 1) to determine the molecular and enzymatic mechanisms underlying the nitrite reductase activity of myoglobin in hypoxia, 2) define critical molecular targets of myoglobin-derived NO and N2O3, and 3) to determine the role of myoglobin in regulating downstream cytoprotective signaling (apoptosis and mitochondrial biogenesis) after ischemia/reperfusion. Successful completion of the proposed research plan will advance our understanding of the biological function of myoglobin and the physiological and pharmacological potential of nitrite in the cardiovascular system.
After a heart attack, part of the tissue in the heart dies. A heart protein called myoglobin can convert nitrite, a chemical found in the diet, to nitric oxide, a chemical that protects heart cells from death. This project will investigate how nitrite and myoglobin work together so that nitrite can be used to protect the heart during a heart attack.
|Khoo, Nicholas K H; Mo, Li; Zharikov, Sergey et al. (2014) Nitrite augments glucose uptake in adipocytes through the protein kinase A-dependent stimulation of mitochondrial fusion. Free Radic Biol Med 70:45-53|
|Kamga Pride, Christelle; Mo, Li; Quesnelle, Kelly et al. (2014) Nitrite activates protein kinase A in normoxia to mediate mitochondrial fusion and tolerance to ischaemia/reperfusion. Cardiovasc Res 101:57-68|
|Sparacino-Watkins, Courtney E; Tejero, Jesús; Sun, Bin et al. (2014) Nitrite reductase and nitric-oxide synthase activity of the mitochondrial molybdopterin enzymes mARC1 and mARC2. J Biol Chem 289:10345-58|
|Simon, Marc A; Lacomis, Christopher D; George, M Patricia et al. (2014) Isolated right ventricular dysfunction in patients with human immunodeficiency virus. J Card Fail 20:414-21|
|Cardenes, Nayra; Corey, Catherine; Geary, Lisa et al. (2014) Platelet bioenergetic screen in sickle cell patients reveals mitochondrial complex V inhibition, which contributes to platelet activation. Blood 123:2864-72|
|Lai, Yen-Chun; Potoka, Karin C; Champion, Hunter C et al. (2014) Pulmonary arterial hypertension: the clinical syndrome. Circ Res 115:115-30|
|Aguilera, J Javier; Zhang, Fuming; Beaudet, Julie M et al. (2014) Divergent effect of glycosaminoglycans on the in vitro aggregation of serum amyloid A. Biochimie 104:70-80|
|Griffin, Paula J; Sebastiani, Paola; Edward, Heather et al. (2014) The genetics of hemoglobin A2 regulation in sickle cell anemia. Am J Hematol 89:1019-23|
|Milton, Jacqueline N; Gordeuk, Victor R; Taylor 6th, James G et al. (2014) Prediction of fetal hemoglobin in sickle cell anemia using an ensemble of genetic risk prediction models. Circ Cardiovasc Genet 7:110-5|
|Tejero, Jesús; Gladwin, Mark T (2014) The globin superfamily: functions in nitric oxide formation and decay. Biol Chem 395:631-9|
Showing the most recent 10 out of 38 publications