a(HBP:"amyloid-beta derived diffusible ligands")
NU1 completely blocked the increase in P-Ser404 and P-Thr231 phosphotau levels induced by ADDLs (Fig. 3D–H). PubMed:17403556
Soluble Aβ can be removed from the brain by various clearance systems, including enzymatic degradation and cellular uptake, transport across the blood–brain barrier (BBB) and blood–cerebrospinal fluid barrier (BCSFB), interstitial fluid (ISF) bulk flow, and cerebro- spinal fluid (CSF) absorption into the circulatory and lymphatic systems. PubMed:26195256
If APP is first cleaved by β-secretase 1 (also known as BACE1) instead of α-secretase, the subsequent γ-secretase cleavage will result in soluble monomeric Aβ. PubMed:26195256
At longer incubation times (48 and 96 h) ADDLs caused a progressive decrease in MTT reduction (Fig. 1B), which can be due to altered trafficking (Liu et al., 1998) as well as cell death. PubMed:17403556
While vehicle treated cells (Fig. 2A and B) exhibited low phosphotau immunofluorescence, cells treated with 1 microM biotinylated ADDLs (bADDLs) for 6 h (Fig. 2C and D) showed a significant increase in P-tau immunofluorescence (Fig. 2D). PubMed:17403556
We then investigated whether bADDLs also induced tau phosphorylation in rat hippocampal neurons. To this end, we initially used frozen dissociated rat hippocampal cell preparations (Cambrex). Cells were maintained in the presence of 1M bADDLs (Fig. 2I and J) or vehicle (not shown) for 6 h at 37 ◦C. We observed a marked P-tau immunostaining in a subpopulation of neurons that also had ADDLs bound (Fig. 2I, arrowheads), while cells that did not bind bADDLs had no AT8 staining (Fig. 2J). PubMed:17403556
Following exposure to ADDLs, double-label immunofluorescence microscopy showed high levels of tau phosphorylated at Thr231, which discriminates among AD and non-AD subjects and patients with other forms of dementia (Hampel et al., 2004, 2003), in neurons with prominent dendritic ADDL binding (detected with NU1, Fig. 2K–M). ADDL binding to synaptic hot-spots in hippocampal neurons is evident in images at highermagnification (60×objective, PanelsLand M). PubMed:17403556
Vehicle-treated neurons (Fig. 3A and E) exhibited very low phosphotau immunofluorescence, but neurons treated for 4 h with 500nM ADDLs showed significantly higher levels in immunofluorescence of P-Ser404 and P-Thr231 tau (Fig. 3B and F, respectively). Neurons treated for 4 h with 10M Abeta fibrils also showed an increase in immunofluorescence of P-Ser404 and P-Thr231 tau (Fig. 3C and G, respectively). PubMed:17403556
Verification of the findings from immunofluorescence microscopy was provided by Western blot analysis of hippocampal neuronal lysates with P404, P231 and P181 antiphosphotau antibodies. A 4 h exposure to 500nM ADDLs resulted in a significant increase in tau phosphorylated at the three epitopes, to levels similar to those observed after exposure to 10 M Abeta fibrils (Fig. 4A–D). PubMed:17403556
Following exposure to ADDLs, double-label immunofluorescence microscopy showed high levels of tau phosphorylated at Thr231, which discriminates among AD and non-AD subjects and patients with other forms of dementia (Hampel et al., 2004, 2003), in neurons with prominent dendritic ADDL binding (detected with NU1, Fig. 2K–M). ADDL binding to synaptic hot-spots in hippocampal neurons is evident in images at highermagnification (60×objective, PanelsLand M). PubMed:17403556
Vehicle-treated neurons (Fig. 3A and E) exhibited very low phosphotau immunofluorescence, but neurons treated for 4 h with 500nM ADDLs showed significantly higher levels in immunofluorescence of P-Ser404 and P-Thr231 tau (Fig. 3B and F, respectively). Neurons treated for 4 h with 10M Abeta fibrils also showed an increase in immunofluorescence of P-Ser404 and P-Thr231 tau (Fig. 3C and G, respectively). PubMed:17403556
Verification of the findings from immunofluorescence microscopy was provided by Western blot analysis of hippocampal neuronal lysates with P404, P231 and P181 antiphosphotau antibodies. A 4 h exposure to 500nM ADDLs resulted in a significant increase in tau phosphorylated at the three epitopes, to levels similar to those observed after exposure to 10 M Abeta fibrils (Fig. 4A–D). PubMed:17403556
Verification of the findings from immunofluorescence microscopy was provided by Western blot analysis of hippocampal neuronal lysates with P404, P231 and P181 antiphosphotau antibodies. A 4 h exposure to 500nM ADDLs resulted in a significant increase in tau phosphorylated at the three epitopes, to levels similar to those observed after exposure to 10 M Abeta fibrils (Fig. 4A–D). PubMed:17403556
A rapid but transient increase was found in the amount of fyn detected in DRMs on ADDL exposure for 2 min that was partially reduced after 10 min exposure. Mirroring the movement of fyn into the DRM, tau content of DRMs increased in response to ADDLs. To further test a putative association between fyn and tau levels in DRMs, we treated cells with 2-bromopalmitate, an inhibitor of protein palmitoylation, which is required for fyn’s localization in DRMs. This treatment resulted in a progressive reduction in both fyn and tau in DRMs, demonstrating that the association of tau with DRMs may be directly regulated by fyn (Supplemental Fig. 2). PubMed:18096814
A rapid but transient increase was found in the amount of fyn detected in DRMs on ADDL exposure for 2 min that was partially reduced after 10 min exposure. Mirroring the movement of fyn into the DRM, tau content of DRMs increased in response to ADDLs. To further test a putative association between fyn and tau levels in DRMs, we treated cells with 2-bromopalmitate, an inhibitor of protein palmitoylation, which is required for fyn’s localization in DRMs. This treatment resulted in a progressive reduction in both fyn and tau in DRMs, demonstrating that the association of tau with DRMs may be directly regulated by fyn (Supplemental Fig. 2). PubMed:18096814
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If you find BEL Commons useful in your work, please consider citing: Hoyt, C. T., Domingo-Fernández, D., & Hofmann-Apitius, M. (2018). BEL Commons: an environment for exploration and analysis of networks encoded in Biological Expression Language. Database, 2018(3), 1–11.