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HIF‐1α reveals a binding activity to the promoter of iNOS gene after permanent middle cerebral artery occlusion
Author(s) -
Matrone C.,
Pignataro G.,
Molinaro P.,
Irace C.,
Scorziello A.,
Di Renzo G. F.,
Annunziato L.
Publication year - 2004
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2004.02483.x
Subject(s) - ischemia , western blot , nitric oxide synthase , lesion , hypoxia (environmental) , hippocampus , middle cerebral artery , pathology , medicine , biology , endocrinology , nitric oxide , chemistry , gene , biochemistry , oxygen , organic chemistry
Hypoxia inducible factor (HIF‐1)‐1α is a specific, oxygen‐sensitive protein that regulates the activity of HIF‐1, a transcriptional factor that increases after cerebral ischemia and may either promote or prevent neuronal survival. In this study to determine whether the inducible nitric oxide synthase (iNOS) gene containing the sequence of the hypoxia‐responsive enhancer (HRE) was an HIF‐1 target after cerebral ischemia induced by permanent middle cerebral artery occlusion (pMCAO), electrophoretic mobility shift assay (EMSA) and iNOS western blot analysis were performed in the ischemic core, in the area surrounding the infarct and in the hippocampus ipsilateral and contralateral to the lesion. In addition, both HIF‐1α mRNA and protein expression were examined in the ischemic core, in the area surrounding the ischemic core and in the hippocampus ipsilateral to the insult. Our results revealed that pMCAO up‐regulates iNOS protein in the ischemic core, in the area surrounding the ischemic core and in the hippocampus ipsilateral to the lesion, and that the activation of iNOS expression is mediated by HIF‐1. Moreover, HIF‐1α mRNA and protein levels increased in the ischemic core and in the hippocampus ipsilateral to the lesion compared with the levels obtained in the corresponding areas of sham‐operated controls or in the contralateral hemisphere. Particularly in the area surrounding the ischemic core, HIF‐1α protein accumulated during pMCAO although mRNA did not increase. Our study suggests that the activation of HIF‐1 might be involved in the mechanisms whereby iNOS promotes cell survival and/or death after cerebral ischemia.