Amyloid-beta peptides induce several chemokine mRNA expressions in the primary microglia and Ra2 cell line via the PI3K/Akt and/or ERK pathway.
ABSTRACT Alzheimer's disease (AD) is characterized by the presence of senile plaques composed primarily of amyloid-beta peptide (Abeta) in the brain. Microglia have been reported to surround these Abeta plaques, which have opposite roles, provoking a microglia-mediated inflammatory response that contributes to neuronal cell loss or the removal of Abeta and damaged neurons. To perform these tasks microglia migrate to the sites of Abeta secretion. We herein analyzed the process of chemokine expression induced by Abeta stimulation in primary murine microglia and Ra2 microglial cell line. We found that Abeta1-42 induced the expressions of CCL7, CCL2, CCL3, CCL4 and CXCL2 in the microglia. The signal transduction pathway for the expression of CCL2 and CCL7 mRNA induced by Abeta1-42 was found to depend on phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK), whereas the pathway for CCL4 depended only on PI3K/Akt. These inflammatory chemokine expressions by Abeta stimulation emphasize the contribution of neuroinflammatory mechanisms to the pathogenesis of AD.
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ABSTRACT: The mammalian target of rapamycin (mTOR) is a highly conserved serine/threonine kinase that can sense environmental stimuli such as growth factors, energy state, and nutrients. It is essential for cell growth, proliferation, and metabolism, but dysregulation of mTOR signaling pathway is also associated with a number of human diseases. Encouraging data from experiments have provided sufficient evidence for the relationship between the mTOR signaling pathway and Alzheimer's disease (AD). Upregulation of mTOR signaling pathway is thought to play an important role in major pathological processes of AD. The mTOR inhibitors such as rapamycin have been proven to ameliorate the AD-like pathology and cognitive deficits effectively in a broad range of animal models. Application of mTOR inhibitors indicates the potential value of reducing mTOR activity as an innovative therapeutic strategy for AD. In this review, we will focus on the recent process in understanding mTOR signaling pathway and the vital involvement of this signaling pathway in the pathology of AD, and discuss the application of mTOR inhibitors as potential therapeutic agents for the treatment of AD.Molecular Neurobiology 07/2013; · 5.29 Impact Factor
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ABSTRACT: The detrimental effect of activation of the chemokine CCL4/MIP-1β on neuronal integrity in patients with HIV-associated dementia has directed attention to the potential role of CCL4 expression and regulation in Alzheimer disease. Here, we show that CCL4 mRNA and protein are overexpressed in the brains of APPswe/PS1ΔE9 (APP/PS1) double-transgenic mice, a model of cerebral amyloid deposition; expression was minimal in brains from nontransgenic littermates or single-mutant controls. Increased levels of CCL4 mRNA and protein directly correlated with the age-related progression of cerebral amyloid-β (Aβ) levels in APP/PS1 mice. We also found significantly increased expression of activating transcription factor 3 (ATF3), which was positively correlated with age-related Aβ deposition and CCL4 in the brains of APP/PS1 mice. Results from chromatin immunoprecipitation-quantitative polymerase chain reaction confirmed that ATF3 binds to the promoter region of the CCL4 gene, consistent with a potential role in regulating CCL4 transcription. Finally, elevated ATF3 mRNA expression in APP/PS1 brains was associated with hypomethylation of the ATF3 gene promoter region. These observations prompt the testable hypothesis for future study that CCL4 overexpression, regulated in part by hypomethylation of the ATF3 gene, may contribute to neuropathologic progression associated with amyloid deposition in Alzheimer disease.Journal of neuropathology and experimental neurology. 03/2014;
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ABSTRACT: Previous mass spectrometry analysis of cerebrospinal fluid (CSF) has allowed the identification of a panel of molecular markers that are associated with Alzheimer's disease (AD). The panel comprises Amyloid beta, Apolipoprotein E, Fibrinogen alpha chain precursor, Keratin type I cytoskeletal 9, Serum albumin precursor, SPARC-like 1 protein and Tetranectin. Here we report the development and implementation of immunoassays to measure the abundance and diagnostic capacity of these putative biomarkers in matched lumbar CSF and blood plasma samples taken in life from individuals confirmed at post-mortem as suffering from AD (n = 10) and from screened 'cognitively healthy' subjects (n = 18). The inflammatory components of Alzheimer's disease were also investigated. Employment of supervised learning techniques permitted examination of the interrelated expression patterns of the putative biomarkers and identified inflammatory components, resulting in biomarker panels with a diagnostic accuracy of 87.5% and 86.7% for the plasma and CSF datasets respectively. This is extremely important as it offers an ideal high-throughput and relatively inexpensive population screening approach. It appears possible to determine the presence or absence of AD based on our biomarker panel and it seems likely that a cheap and rapid blood test for AD is feasible.International Journal of Molecular Epidemiology and Genetics 01/2014; 5(2):53-70.