Journal
FRONTIERS IN NEUROSCIENCE
Volume 11, Issue -, Pages -Publisher
FRONTIERS MEDIA SA
DOI: 10.3389/fnins.2017.00217
Keywords
amyloid-beta; Tau; adult human astrocytes; exosome; calcium-sensing receptor; calcilytics; Alzheimer's; disease; GSK-3 beta
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Funding
- Italian Ministry for University and Research (F.U.R.)
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The two main drivers of Alzheimer's disease (AD), amyloid-beta (4) and hyperphosphorylated Tau (p-Tau) oligomers, cooperatively accelerate AD progression, but a hot debate is still ongoing about which of the two appears first. Here we present preliminary evidence showing that Tau and p-Tau are expressed by untransformed cortical adult human astrocytes in culture and that exposure of such cells to an 442 proxy, A beta(25-35), which binds the calcium sensing receptor (CaSR) and activates its signaling, significantly increases intracellular p-Tau levels, an effect CaSR antagonist (calcilytic) NPS 2143 wholly hinders. The astrocytes also release both Tau and p-Tau by means of exosomes into the extracellular medium, an activity that could mediate p-Tau diffusion within the brain. Preliminary data also indicate that exosomal levels of p-Tau increase after A beta(25-35) exposure, but remain unchanged in cells pre-treated for 30-min with NPS 2143 before adding A beta(25-35). Thus, our previous and present findings raise the unifying prospect that A beta.CaSR signaling plays a crucial role in AD development and progression by simultaneously activating (i) the amyloidogenic processing of amyloid precursor holoprotein, whose upshot is a surplus production and secretion of 442 oligomers, and (ii) the GSK-3 beta-mediated increased production of p-Tau oligomers which are next released extracellularly inside exosomes. Therefore, as calcilytics suppress both effects on A beta(42) and p-Tau metabolic handling, these highly selective antagonists of pathological A beta.CaSR signaling would effectively
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