Elevated levels of homocysteine (Hcy) known as hyperhomocysteinemia (HHcy) are associated with cardiac arrhythmia and sudden cardiac death (SCO). Hey increases the iNOS, activates matrix metalloproteinase (MMP), disrupts connexin-43 and increases collagen/elastin ratio. The disruption of connexin-43 and accumulation of collagen (fibrosis) interrupts cardiac conduction and attenuate NO transport from endothelium to myocyte (E-M) causing E-M uncoupling. The novelty of this proposal is that Hcy behaves as an agonist to N-methyl-D-aspartate (NMDA, an excitatory neurotransmitter) receptor-1, and blockade of NMDA-R1 reduces SCO. The central hypothesis of this proposal is that Hcy increases iNOS, mtNOS activities, superoxide levels, metalloproteinase activity, disrupts connexin-43, exacerbates endothelial-myocyte uncoupling, and induces cardiac failure by activating NMDA-R1.
Specific Aim #1 : To determine whether Hey exacerbates heart failure and endothelial-myocyte uncoupling by increasing iNOS and rendering ineffective eNOS and nNOS by behaving as an agonist to NMDA-R1. CBS heterozygote (-/+) knockout (CBSKO) mice will be crossbred with iNOS homozygote (-/-) knockout (iNOSKO) mice, producing wild type (WT), CBSKO, iNOSKO and CBS/iNOS (-/+;-/-) double knockout (doubleKO). In these mice, chronic volume overload heart failure will be created by aorta-venacava (AV) fistula. NMDA-R1 will be blocked by dizocilpine (MK-801). The endothelial-myocyte coupling will be determined in cardiac rings. LV levels of NMDA-R1, iNOS, nNOS and eNOS will be measured.
Specific Aim #2 : To determine whether Hey increases MMP-2, -9, -13, ADAM-12, decreases TIMP-4, and degrades connexin-43 in heart failure by inducing NMDA-R1. MMP and TIMP activities will be measured by innovative 2-zymography (MMP functional proteomics) and reverse zymography, respectively. The degradation of connexin-43, collagen and elastin will be measured by Western analysis.
Specific Aim #3 : To determine whether Hey decreases LV mitochondrial thioredoxin, peroxiredoxin, and SOD, and increases NADH oxidase and mtNOS activity in heart failure by activating NMDA-R1. In hearts, in situ labeling will be performed for thioredoxin, peroxiredoxin, SOD, and NADH oxidase. These studies will delineate the mechanism of Hcy-dependent endothelial-myocyte uncoupling in cardiac arrhythmia and failure, and will have therapeutic ramifications for sudden cardiac death.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Special Emphasis Panel (ZRG1-CVS-D (02))
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Wang, Lan-Hsiang
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University of Louisville
Schools of Medicine
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Soni, Chirag V; Tyagi, Suresh C; Todnem, Nathan D et al. (2016) Hyperhomocysteinemia Alters Sinoatrial and Atrioventricular Nodal Function: Role of Magnesium in Attenuating These Effects. Cell Biochem Biophys 74:59-65
Vacek, Thomas P; Rehman, Shahnaz; Neamtu, Diana et al. (2015) Matrix metalloproteinases in atherosclerosis: role of nitric oxide, hydrogen sulfide, homocysteine, and polymorphisms. Vasc Health Risk Manag 11:173-83
Qipshidze, Natia; Tyagi, Neetu; Metreveli, Naira et al. (2012) Autophagy mechanism of right ventricular remodeling in murine model of pulmonary artery constriction. Am J Physiol Heart Circ Physiol 302:H688-96
Vacek, Thomas P; Vacek, Jonathan C; Tyagi, Neetu et al. (2012) Autophagy and heart failure: a possible role for homocysteine. Cell Biochem Biophys 62:1-11
Givvimani, Srikanth; Munjal, Charu; Tyagi, Neetu et al. (2012) Mitochondrial division/mitophagy inhibitor (Mdivi) ameliorates pressure overload induced heart failure. PLoS One 7:e32388
Mishra, Paras Kumar; Chavali, Vishalakshi; Metreveli, Naira et al. (2012) Ablation of MMP9 induces survival and differentiation of cardiac stem cells into cardiomyocytes in the heart of diabetics: a role of extracellular matrix. Can J Physiol Pharmacol 90:353-60
Vacek, Thomas P; Vacek, Jonathan C; Tyagi, Suresh C (2012) Mitochondrial mitophagic mechanisms of myocardial matrix metabolism and remodelling. Arch Physiol Biochem 118:31-42
Sen, Utpal; Sathnur, Pushpakumar B; Kundu, Sourav et al. (2012) Increased endogenous H2S generation by CBS, CSE, and 3MST gene therapy improves ex vivo renovascular relaxation in hyperhomocysteinemia. Am J Physiol Cell Physiol 303:C41-51
Qipshidze, Natia; Metreveli, Naira; Mishra, Paras K et al. (2012) Hydrogen sulfide mitigates cardiac remodeling during myocardial infarction via improvement of angiogenesis. Int J Biol Sci 8:430-41
Qipshidze, Natia; Metreveli, Naira; Lominadze, David et al. (2011) Folic acid improves acetylcholine-induced vasoconstriction of coronary vessels isolated from hyperhomocysteinemic mice: an implication to coronary vasospasm. J Cell Physiol 226:2712-20

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