THE REGULATORY ROLE OF NF-κB IN AUTOPHAGY-LIKE CELL DEATH AFTER FOCAL CEREBRAL ISCHEMIA IN MICE

Autophagy may contribute to ischemia-induced cell death in the brain, but the regulation of autophagic cell death is largely unknown. Nuclear factor kappa B (NF-kappa B) is a regulator of apoptosis in cerebral ischemia. We examined the hypothesis that autophagy-like cell death could contribute to ischemia-induced brain damage and the process was regulated by NF-kappa B. In adult wild-type (WT) and NF-kappa B p50 knockout (p50(-/-)) mice, focal ischemia in the barrel cortex was induced by ligation of distal branches of the middle cerebral artery. Twelve to 24 h later, autophagic activity increased as indicated by enhanced expression of Beclin-1 and LC3 in the ischemic core and/or penumbra regions. This increased autophagy contributed to cell injury, evidenced by terminal deoxynucleotidyltransferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) co-staining and a protective effect achieved by the autophagy inhibitor 3-methyladenine. The number of Beclin-1/TUNEL-positive cells was significantly more in p50(-/-) mice than in WT mice. Neuronal and vascular cell death, as determined by TUNEL-positive cells co-staining with NeuN or Collagen IV, was more abundant in p50(-/-) mice. Immunostaining of the endothelial cell tight junction marker occludin revealed more damage to the blood-brain barrier in p50(-/-) mice. Western blotting of the peri-infarct tissue showed a reduction of Akt-the mammalian target of rapamycin (mTOR) signaling in p50(-/-) mice after ischemia. These findings provide the first evidence that cerebral ischemia induced autophagy-like injury is regulated by the NF-kappa B pathway, which may suggest potential treatments for ischemic stroke. (c) 2013 IBRO. Published by Elsevier Ltd. All rights reserved.