The transcription factor interferon regulatory factor 1 is expressed aftercerebral ischemia and contributes to ischemic brain injury

The transcription factor interferon regulatory factor 1 (IRF-1) is involved in the molecular mechanisms of inflammation and apoptosis, processes that contribute to ischemic brain injury. In this study, the induction of IRF-1 in response to cerebral ischemia and its role in ischemic brain injury were investigated. IRF-1 gene expression was markedly upregulated within 12 h o f occlusion of the middle cerebral artery in C57BL/6 mice. The expression r eached a peak 4 d after ischemia (6.0 +/- 1.8-fold; P < 0.001) and was rest ricted to the ischemic regions of the brain. The volume of ischemic injury was reduced by 23 +/- 3% in IRF-1(+/-) and by 46 +/- 9% in IRF-1(-/-) mice (P < 0.05). The reduction in infarct volume was paralleled by a substantial attenuation in neurological deficits. Thus, IRF-1 is the first nuclear tra nsacting factor demonstrated to contribute directly to cerebral ischemic da mage and may be a novel therapeutic target in ischemic stroke.