May 2005
Volume 46, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2005
Increased Extracellular Glutamate Induces Oxidation of Key Mitochondrial Enzymes
Author Affiliations & Notes
  • L.D. Carter–Dawson
    Opthalmology & Visual Sciences, UT Health Science Center, Houston, TX
  • A. Whitetree
    Opthalmology & Visual Sciences, UT Health Science Center, Houston, TX
  • R. Rojas
    Opthalmology & Visual Sciences, UT Health Science Center, Houston, TX
  • Footnotes
    Commercial Relationships  L.D. Carter–Dawson, None; A. Whitetree, None; R. Rojas, None.
  • Footnotes
    Support  NIH Grant EY10608 and Research to Prevent Blindness
Investigative Ophthalmology & Visual Science May 2005, Vol.46, 1616. doi:
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      L.D. Carter–Dawson, A. Whitetree, R. Rojas; Increased Extracellular Glutamate Induces Oxidation of Key Mitochondrial Enzymes . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1616.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: Mitochondrial proteins are known to become nitrated in disease systems, altering their function and potentially compromising the cell, leading to cell death. Nitration of manganese superoxide dismutase (MnSOD) and OxPhos complex II reduces their activities and contributes to further generation of reactive oxygen species and oxidative damage to mitochondria. Nitration of cytochrome c leads to its release from mitochondria and initiation of apoptosis. The purpose of the current study is to determine whether increased extracellular glutamate promotes nitration of MnSOD, cytochrome c and OxPhos complex II. Methods: Extracellular glutamate was raised in male Sprague–Dawley rats in the inner plexiform layer by intraocular dihydrokainic acid (DHK) injection to block the GLT–1 glutamate transporter. Under deep anesthesia, eyes were removed and retinas dissected from the eye cup, homogenized and aliquots were prepared for SDS–PAGE or immunoprecipitated with antibodies to nitrotyrosine and then separated by SDS–PAGE. Proteins were transferred to nitrocellulose membranes and probed with antibodies to MnSOD, cytochrome c, or OxPhos complex II. Results: Western blot analysis of immunoprecipitated nitrated proteins revealed an increase in MnSOD, cytochrome c, and OxPhos complex II by four and seven days after DHK treatment compared to controls. Conclusions: Increased extracellular glutamate leads to nitration of key mitochondrial enzymes in the retina. The increased nitration of mitochondrial proteins (MnSOD, cytochrome c, and OxPhos complex II) represents a pathway by which increased extracellular glutamate leads to cell compromise and death.

Keywords: oxidation/oxidative or free radical damage • excitatory neurotransmitters • mitochondria 
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