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Article Allele-specific silencing of Alzheimer's disease genes: the amyloid precursor protein genes with Swedish or London mutations. 2006
Feng X, Zhao P, He Y, Zuo Z. · Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908, USA. · Gene. · Pubmed #16426772 No free full text.
Abstract: Alzheimer's disease (AD) is the most common cause of dementia in humans. A pathological hallmark in the brain of an AD patient is extracellular amyloid plaques formed by accumulated beta-amyloid protein (Abeta), a metabolic product of amyloid precursor protein (APP). Studies have revealed a strong genetic linkage in the early-onset familial form (<60 years old) of AD. For example, some mutant APPs are transmitted dominantly and are segregated with inheritance of early onset AD. These mutants facilitate Abeta production. The "Swedish" mutations (APP(SW)) and the "London" mutation (APP(LON)) are examples of these mutants. Selective silencing of these mutant alleles holds therapeutic promise for AD. Here we show that the expression of the mutant APPs was selectively inhibited by RNA interference. The best selectivity was obtained when the mismatches were centrally placed in the antisense strand of small interfering RNAs. Introducing an additional mismatch in the antisense strand may improve the selectivity. The addition of a G at 5' end of the antisense strand may enhance the efficacy of gene silencing by RNA interference. Our results illustrate the guiding principles for selection of targeted sequences to achieve allele-specific silencing. The sequences that are effective to silence APP(SW) and APP(LON) as identified in this study may be useful in both in vivo and in vitro studies to investigate the pathophysiological role of APP(SW) and APP(LON) in AD development.
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Article Adeno-associated viral vector-mediated ApoE expression in Alzheimer's disease mice: low CNS immune response, long-term expression, and astrocyte specificity. 2004
Feng X, Eide FF, Jiang H, Reder AT. · Department of Neurology, University of Chicago, Chicago, IL 60637-1470, USA. · Front Biosci. · Pubmed #14977565 No free full text.
Abstract: Recombinant Adenovirus and Adeno-associated virus (AAV) are highly effective vehicles for gene transfer into CNS cells. However, the duration of gene expression and the cytotoxicity to cells are quite different between these viral approaches. We initially investigated these distinctions by stereotaxically injecting both Adenovirus vector and AAV vectors expressing reporter genes into mouse hippocampus. The adenovirus vector induced a pronounced immune response with a marked increase in CD45 and MHC class I protein expression and transgene expression was shorter than six weeks. In contrast, with the AAV vector there was lower expression of CD45 and MHC class I immune activation markers, and longer expression of reporter gene (up to 12 months). To study the roles of human Apolipoprotein E (ApoE) alleles in the pathogenesis of Alzheimer's disease and other CNS diseases, we generated recombinant AAV-apoE alleles driven by the GFAP promoter and expressed them in the mouse brain of Alzheimer's disease mouse. High level ApoE expressions in mouse brain lasted for 12 months, and ApoE was specifically expressed in astrocytes. We demonstrate that AAV-GFAP-ApoE is valuable in studying the pathogenesis and in gene therapy for Alzheimer's disease and other CNS diseases.
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