http://www.fasebj.org/content/early/2017/01/15/fj.201601033R.abstract
- Cameron Rink1,
- Surya Gnyawali,
- Richard Stewart,
- Seth Teplitsky,
- Hallie Harris,
- Sashwati Roy,
- Chandan K. Sen and
- Savita Khanna2
+ Author Affiliations
- ↵1Correspondence: 473 W. 12th Ave., Columbus, OH 43210, USA. E-mail: cameron.rink@osumc.edu
- ↵2Correspondence: 473 W. 12th Ave., Columbus, OH 43210, USA. E-mail: savita.khanna@osumc.edu
Abstract
Ischemic stroke results in excessive
release of glutamate, which contributes to neuronal cell death. Here, we
test the hypothesis
that otherwise neurotoxic glutamate can be
productively metabolized by glutamate oxaloacetate transaminase (GOT) to
maintain
cellular energetics and protect the brain from
ischemic stroke injury. The GOT-dependent metabolism of glutamate was
studied
in primary neural cells and in stroke-affected
C57-BL6 mice using magnetic resonance spectroscopy and GC-MS.
Extracellular
Glu sustained cell viability under hypoglycemic
conditions and increased GOT-mediated metabolism in vitro. Correction of stroke-induced hypoxia using supplemental oxygen in vivo lowered Glu levels as measured by 1H
magnetic resonance spectroscopy. GOT knockdown abrogated this effect
and caused ATP loss in the stroke-affected brain. GOT
overexpression increased anaplerotic refilling of
tricarboxylic acid cycle intermediates in mouse brain during ischemic
stroke.
Furthermore, GOT overexpression not only reduced
ischemic stroke lesion volume but also attenuated neurodegeneration and
improved
post-stroke sensorimotor function. Taken together,
our results show that GOT enables metabolism of otherwise neurotoxic
extracellular
Glu through a truncated tricarboxylic acid cycle
under hypoglycemic conditions.—Rink, C., Gnyawali, S., Stewart, R.,
Teplitsky,
S., Harris, H., Roy, S., Sen, C. K., Khanna, S.
Glutamate oxaloacetate transaminase enables anaplerotic refilling of TCA
cycle
intermediates in stroke-affected brain.
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