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A Mouse Model of Retinal Ischemia-Reperfusion Injury Through Elevation of Intraocular Pressure
Published on: July 14, 2016
Brain ischemia and reperfusion activates the eukaryotic initiation factor 2alpha kinase, PERK
R Kumar1, S Azam, J M Sullivan
1Department of Emergency Medicine, Wayne State University, Detroit, Michigan 48201, USA.
Journal of Neurochemistry
|June 5, 2001
Summary
Global brain ischemia reperfusion suppresses protein synthesis by inhibiting translation initiation. This study identifies the RNA-dependent protein kinase (PKR)-like endoplasmic reticulum kinase (PERK) as the key enzyme responsible for this early post-ischemic effect.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Global brain ischemia and reperfusion trigger widespread protein synthesis suppression in neurons.
- This suppression is linked to the inhibition of translation initiation, mediated by the phosphorylation of eukaryotic initiation factor 2 alpha (eIF2alpha).
Purpose of the Study:
- To identify the specific kinases responsible for eIF2alpha phosphorylation during brain reperfusion.
- To investigate the roles of heme-regulated eIF2alpha kinase (HRI) and amino acid-regulated eIF2alpha kinase (GCN2) in this process.
Main Methods:
- Global brain ischemia was induced in mice via bilateral carotid artery occlusion.
- Post-ischemic brain eIF2alpha phosphorylation levels were assessed in wild-type mice and in knockout mice lacking functional HRI or GCN2.
- Activation of PERK was evaluated using SDS-PAGE to detect isoform mobility shifts.
Main Results:
- A significant 10-fold increase in eIF2alpha phosphorylation was observed in reperfused wild-type, HRI-/-, and GCN2-/- mice.
- The RNA-dependent protein kinase (PKR)-like endoplasmic reticulum eIF2alpha kinase (PERK) showed an activation-consistent mobility shift in all reperfused groups.
- Neither HRI nor GCN2 were found to be essential for the elevated eIF2alpha phosphorylation post-ischemia.
Conclusions:
- HRI and GCN2 are not the primary kinases responsible for increased eIF2alpha phosphorylation in the early stages of brain reperfusion.
- These findings, combined with prior data on PKR knockout mice, strongly implicate PERK as the key kinase driving eIF2alpha phosphorylation in the post-ischemic brain.
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