Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aberrant proteolytic processing of the amyloid precursor protein (APP) by beta- and gamma-secretases is key to amyloid plaque formation in Alzheimer's disease (AD). Identification of an aspartyl protease as the beta-secretase (beta-site APP cleaving enzyme, BACE) involved in APP processing provides a pharmaceutical target for potential AD treatment. In the present studies, we demonstrate that transient cerebral ischemia in female rats caused a 30% increase in beta-secretase activity. alpha-Secretase activity did not increase significantly. We examined protein levels of BACE1, and its analogue BACE2, in ischemic brain extracts. BACE1 protein levels increased 67%, while BACE2 protein level did not change after such a transient ischemia. Immunohistochemical studies demonstrated that BACE1 protein was increased in the ischemic neocortex, when compared with its contralateral cortex. Further, colocalization assessment indicated that BACE1 strongly associated with staining for the apoptotic marker, TUNEL. These results may partially explain epidemiological study, which demonstrate a higher incidence of dementia after stroke. Further, our results support the hypothesis that apoptosis and aberrant APP processing are correlated events in AD brain, and suggest that inhibition of BACE may have a therapeutic effect in the prevention of dementia after stroke recovery.
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PMID:Increased beta-secretase activity and expression in rats following transient cerebral ischemia. 1512 May 77

While it is well established that stroke and cerebral hypoperfusion are both significant risk factors for Alzheimer's disease, the molecular link between ischemia and amyloid precursor protein processing has only been recently established. Specifically, hypoxia significantly increases beta-site APP cleaving enzyme (BACE1) gene transcription through the over-expression of hypoxia inducible factor 1alpha, resulting in increased BACE1 secretase activity and amyloid-beta production. In this study, we significantly extend these findings both in vitro, in differentiated SK-N-BE neuroblastoma cells, and in vivo, in rats subjected to cerebral ischemia, showing that hypoxia up-regulates BACE1 expression through a biphasic mechanism. The early post-hypoxic up-regulation of BACE1 depends on the production of reactive oxygen species mediated by the sudden interruption of the mitochondrial electron transport chain, while the later expression of BACE1 is caused by hypoxia inducible factor 1alpha activation. The involvement of reactive oxygen species released by mitochondria in the BACE1 up-regulation was confirmed by the complete protection exerted by complex I inhibitors such as rotenone and diphenyl-phenylen iodonium. Moreover, the oxidative stress-mediated up-regulation of BACE1 is mediated by c-jun N terminal kinase pathway as demonstrated by the protection exerted by the silencing of c-jun N-terminal kinase isoforms 1 and 2. Our study strengthens the hypothesis that oxidative stress is a basic common mechanism of amyloid-beta accumulation.
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PMID:The up-regulation of BACE1 mediated by hypoxia and ischemic injury: role of oxidative stress and HIF1alpha. 1919 31

Peroxisome proliferator-activated receptor gamma (PPARgamma) has already been considered as an attractive therapeutic target for the treatment of metabolic disorders. Recently, PPARgamma agonists were shown to effectively attenuate oxidative stress, inflammation and apoptosis in the central nervous system. There are several preclinical and clinical studies indicating neuroprotective potential of PPARgamma agonists in the treatment of cerebral ischemia, Parkinson's disease, Alzheimer's disease, multiple sclerosis and amyotrophic lateral sclerosis. In these disorders, apart from inhibiting oxidative stress, inflammation and apoptosis, PPARgamma agonists have the potential to modulate various signaling molecules/pathways, including matrix metalloproteinase-9, mitogen-activated protein kinases, signal transducer and activator of transcription, mitochondrial uncoupling protein 2, mitoNEET expression, amyloid precursor protein degradation, beta-site amyloid precursor protein cleaving enzyme 1 and Wnt signaling. This article discusses evidence and mechanisms supporting the neuroprotective effects of PPARgamma agonists in central nervous system disorders.
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PMID:Peroxisome proliferator-activated receptor gamma agonists as neuroprotective agents. 2052 Aug 53