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P2‐236: microRNA mediated reversal of AD pathology
Author(s) -
Zimmer Danna,
Roltsch Emily,
Miranda Rajesh
Publication year - 2010
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2010.05.1285
Subject(s) - microrna , biology , gene expression profiling , gene , gene expression , microarray , downregulation and upregulation , regulation of gene expression , genetics
Background: HSV-1 is a neurotropic virus that, following primary infection, usually establishes a lifelong latent infection in the trigeminal ganglion. Following periodic reactivations, the newly produced viral particles may be transported to the central nervous system (CNS), resulting in productive but usually asymptomatic infections. Possible links between recurrent HSV-1 infections and Alzheimer’s disease (AD) have emerged from epidemiological studies and experimental findings. We have recently found that HSV-1 produces marked changes in neuronal excitability and intracellular Ca2+ signalling which affect the phosphorylation of amyloid precursor protein (APP) and result in intracellular accumulation of amyloid-b peptide (Ab). The present study was aimed at investigating the effects of productive HSV-1 infections on APP processing in neuronal cells. Methods: SH-SY5Y human neuroblastoma cells and cortical neurons obtained from E17-E18 rat embryos were challenged with wild-type HSV-1 or HSV-1 mutants deleted in VHS (DUL41) or UL34.5 (Dg34.5) genes. All strains productively infected cells. Western blot analysis of proteins from cell lysates or TCA-precipitated supernatants was performed by using different anti-APP antibodies. Ab40 and Ab42 were detected by immunocytochemistry. Results: In both SHSY5Y cells and rat cortical neurons HSV-1 infection triggered APP processing which generated the following species: i) two Ab-containing APP fragments (APP-Fs) with molecular weights of 35 (APP-F35) and 45 KDa (APPF45); ii) secreted N-terminal APP-Fs; iii) intracellular C-terminal APP-Fs; iv) Ab40 and Ab42. WB analysis of cell lysates treated with formic acid suggests that APP-F35 is an oligomeric form of Ab whose electrophoretic mobility is consistent with that of Ab nonamer. The APP processing seen in infected cells consisted of multiple cleavages which were produced, at least in part, by cellular enzymes that are known components of the amyloidogenic APP processing pathway, i.e., band g-secretases, and caspase-3 like enzymes. Conclusions: Collectively, our findings indicate that HSV-1 infection affects APP processing leading to the production of APP fragments with documented neurotoxic potential. It is tempting to speculate that, in the presence of other genetic or environmental risk factors, repeated cycles of viral reactivation within the CNS could play a co-factorial role in AD pathogenesis by causing intraand extracellular accumulation of Ab and other neurotoxic APP fragments.