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.

Public Health Relevance

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.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL096973-04
Application #
8453430
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Schwartz, Lisa
Project Start
2010-04-15
Project End
2014-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
4
Fiscal Year
2013
Total Cost
$345,471
Indirect Cost
$91,178
Name
University of Pittsburgh
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Corti, Paola; Xue, Jianmin; Tejero, Jesús et al. (2016) Globin X is a six-coordinate globin that reduces nitrite to nitric oxide in fish red blood cells. Proc Natl Acad Sci U S A 113:8538-43
Simon, Marc A; Vanderpool, Rebecca R; Nouraie, Mehdi et al. (2016) Acute hemodynamic effects of inhaled sodium nitrite in pulmonary hypertension associated with heart failure with preserved ejection fraction. JCI Insight 1:e89620
Lai, Yen-Chun; Tabima, Diana M; Dube, John J et al. (2016) SIRT3-AMP-Activated Protein Kinase Activation by Nitrite and Metformin Improves Hyperglycemia and Normalizes Pulmonary Hypertension Associated With Heart Failure With Preserved Ejection Fraction. Circulation 133:717-31
Saraf, Santosh L; Zhang, Xu; Shah, Binal et al. (2015) Genetic variants and cell-free hemoglobin processing in sickle cell nephropathy. Haematologica 100:1275-84
Tejero, Jesús; Sparacino-Watkins, Courtney E; Ragireddy, Venkata et al. (2015) Exploring the mechanisms of the reductase activity of neuroglobin by site-directed mutagenesis of the heme distal pocket. Biochemistry 54:722-33
Wang, Jun; Krizowski, Sabina; Fischer-Schrader, Katrin et al. (2015) Sulfite Oxidase Catalyzes Single-Electron Transfer at Molybdenum Domain to Reduce Nitrite to Nitric Oxide. Antioxid Redox Signal 23:283-94
Madigan, Michael C; McEnaney, Ryan M; Shukla, Ankur J et al. (2015) Xanthine Oxidoreductase Function Contributes to Normal Wound Healing. Mol Med 21:313-22
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
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

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