Mechanisms of Mitochondrial Dysfunction in Brain Vasculature

Summary

Principal Investigator: Neetu Tyagi
Abstract: DESCRIPTION (provided by applicant): Clinical data suggest an association between elevated levels of Hcy, also known as hyperhomocysteine-mia (HHcy) and stroke. HHcy is generated due to increase in de-methylation of methionine by S-adenosine- homocysteine hydrolase (SAHH) and a decrease in methyltetrahydrofolate reductase (MTHFR) and cystathionine-y-lyase (CSE, an enzyme responsible for Hcy metabolism to H2S, a most potent vasodilator, antioxidant and anti-hypertensive agent) contribute to mitochondria dysfunction (mitophagy) and ischemic stroke. Cytochrome-C transports electrons and facilitates mitochondrial bioenergetics. Interestingly, during HHcy, cytochrome-C becomes homocysteinylated (N-Hcy-cyt-c). However, it's consequence to mitophagy and stroke is unclear. The long-term goal of this project is to understand the mechanism of mitophagy, mitochondrial repair and permeability in brain vasculature during I/R injury. Our preliminary studies suggest that during I/R ,total Hcy levels increases, causes N-Hcy-cyt-C , increases mitochondrial matrix metalloproteinase-9 (mtMMP-9), in-part degradation of mt-matrix (connexin and tight junction protein, TJP) which led to mitophagy and permeability in brain vasculature. Interestingly, THC decreases Hcy level and mitigates brain damage. Tetra hydro-curcumin (THC), a major herbal antioxidant and anti-inflammatory agent, has shown to protect brain against I/R injury. The central hypothesis of this proposal is that HHcy contributes to mitophagy mediated brain damage through N-Hcy-cyt-C in part, by increasing oxidative stress, mtMMP-9, degrades connexin-43 and TJP (Figure 1). The treatment with THC, CSE gene and SAHH shRNA gene transfer attenuates mitophagy and permeability. We will test this hypothesis by following three specific aims: Specific Aim #1: To determine whether the Hcy contributes to mitophagy, in part by inducing oxidative stress, exacerbating homocysteinylation of cytochrome-c in ischemia reperfusion and if THC, CSE and SAHH shRNA gene therapy mitigates these changes. Specific Aim #2: To determine whether the homocysteinylation of cytochrome-c activates mt-MMP-9, disruption of collagen/elastin ratio, mtCxn43 and mt-tight junction proteins in ischemia reperfusion and if THC, CSE and SAHH shRNA gene therapy ameliorate. Specific Aim #3: To determine whether Hcy alters mitochondrial (mt) bioenergetics and cerebro-vascular remodeling in ischemia reperfusion and if THC, CSE and SAHH shRNA gene therapy alleviate. These studies will demonstrate the novel mechanism of cerebrovascular remodeling and have therapeutic ramifications for mitochondrial repair in cerebral ischemic stroke.
Funding Period: 2012-03-01 - 2017-02-28
more information: NIH RePORT

Top Publications

  1. pmc Tetrahydrocurcumin ameliorates homocysteinylated cytochrome-c mediated autophagy in hyperhomocysteinemia mice after cerebral ischemia
    Neetu Tyagi
    Department of Physiology and Biophysics, School of Medicine, Health Sciences Center, A 1115, University of Louisville, Louisville, KY 40202, USA
    J Mol Neurosci 47:128-38. 2012
  2. pmc Synergy of homocysteine, microRNA, and epigenetics: a novel therapeutic approach for stroke
    Anuradha Kalani
    Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA
    Mol Neurobiol 48:157-68. 2013
  3. pmc The role of homocysteine in bone remodeling
    Thomas P Vacek
    Department of Physiology and Biophysics, University of Louisville School of Medicine Louisville, Louisville, KY 40202, USA
    Clin Chem Lab Med 51:579-90. 2013
  4. pmc Hydrogen sulfide attenuates neurodegeneration and neurovascular dysfunction induced by intracerebral-administered homocysteine in mice
    P K Kamat
    Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA
    Neuroscience 252:302-19. 2013
  5. pmc Exosomes: mediators of neurodegeneration, neuroprotection and therapeutics
    Anuradha Kalani
    Department of Physiology and Biophysics, School of Medicine, Health Sciences Center, A 1201, University of Louisville, 500 South Preston Street, Louisville, KY, 40202, USA
    Mol Neurobiol 49:590-600. 2014
  6. pmc Curcumin-primed exosomes mitigate endothelial cell dysfunction during hyperhomocysteinemia
    A Kalani
    Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA
    Life Sci 107:1-7. 2014
  7. ncbi Autophagy of mitochondria: a promising therapeutic target for neurodegenerative disease
    Pradip K Kamat
    Department of Physiology and Biophysics, School of Medicine, Health Sciences Center, University of Louisville, A 1201, Louisville, KY, 40202, USA
    Cell Biochem Biophys 70:707-19. 2014

Research Grants

  1. DEGENERATIVE AND DEMENTING DISEASES OF AGING
    Stanley B Prusiner; Fiscal Year: 2013
  2. Mechanisms of Atherogenesis in Insulin Resistance
    IRA A TABAS; Fiscal Year: 2013

Detail Information

Publications9

  1. pmc Tetrahydrocurcumin ameliorates homocysteinylated cytochrome-c mediated autophagy in hyperhomocysteinemia mice after cerebral ischemia
    Neetu Tyagi
    Department of Physiology and Biophysics, School of Medicine, Health Sciences Center, A 1115, University of Louisville, Louisville, KY 40202, USA
    J Mol Neurosci 47:128-38. 2012
    ..This study suggests a potential therapeutic role of dietary THC in cerebral ischemia...
  2. pmc Synergy of homocysteine, microRNA, and epigenetics: a novel therapeutic approach for stroke
    Anuradha Kalani
    Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA
    Mol Neurobiol 48:157-68. 2013
    ..The review also highlights possible epigenetic mechanisms, potential therapeutic molecules, putative challenges, and approaches to deal with stroke during HHcy...
  3. pmc The role of homocysteine in bone remodeling
    Thomas P Vacek
    Department of Physiology and Biophysics, University of Louisville School of Medicine Louisville, Louisville, KY 40202, USA
    Clin Chem Lab Med 51:579-90. 2013
    ..However, more studies are needed to clarify the mechanistic role of Hcy during bone diseases...
  4. pmc Hydrogen sulfide attenuates neurodegeneration and neurovascular dysfunction induced by intracerebral-administered homocysteine in mice
    P K Kamat
    Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA
    Neuroscience 252:302-19. 2013
    ..The results indicate that H2S is effective in providing protection against neurodegeneration and neurovascular dysfunction...
  5. pmc Exosomes: mediators of neurodegeneration, neuroprotection and therapeutics
    Anuradha Kalani
    Department of Physiology and Biophysics, School of Medicine, Health Sciences Center, A 1201, University of Louisville, 500 South Preston Street, Louisville, KY, 40202, USA
    Mol Neurobiol 49:590-600. 2014
    ..This review is focused on the role of exosomes in mediating neurodegeneration and neuroprotection. ..
  6. pmc Curcumin-primed exosomes mitigate endothelial cell dysfunction during hyperhomocysteinemia
    A Kalani
    Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA
    Life Sci 107:1-7. 2014
    ..5 μM), release an alleviated exosome population that can help recover the endothelial cell (EC) layer permeability...
  7. ncbi Autophagy of mitochondria: a promising therapeutic target for neurodegenerative disease
    Pradip K Kamat
    Department of Physiology and Biophysics, School of Medicine, Health Sciences Center, University of Louisville, A 1201, Louisville, KY, 40202, USA
    Cell Biochem Biophys 70:707-19. 2014
    ..This review also explores new approaches that can prevent mitochondrial dysfunction, improve neurodegenerative etiology, and also offer possible cures to the aforementioned neurodegenerative diseases. ..

Research Grants30

  1. DEGENERATIVE AND DEMENTING DISEASES OF AGING
    Stanley B Prusiner; Fiscal Year: 2013
    ..The ultimate goal of all the proposed studies is to define the molecular events that feature in the formation of human prions in order to develop therapeutics that cure the human prion diseases. ..
  2. Mechanisms of Atherogenesis in Insulin Resistance
    IRA A TABAS; Fiscal Year: 2013
    ..End of Abstract) ..