Effects of Heparin and Enoxaparin on APP Processing and Aβ Production in Primary Cortical Neurons from Tg2576 Mice

Abstract

BackgroundAlzheimer's disease (AD) is caused by accumulation of Aβ, which is produced through sequential cleavage of β-amyloid precursor protein (APP) by the β-site APP cleaving enzyme (BACE1) and γ-secretase. Enoxaparin, a low molecular weight form of the glycosaminoglycan (GAG) heparin, has been reported to lower Aβ plaque deposition and improve cognitive function in AD transgenic mice.Methodology/Principal FindingsWe examined whether heparin and enoxaparin influence APP processing and inhibit Aβ production in primary cortical cell cultures. Heparin and enoxaparin were incubated with primary cortical cells derived from Tg2576 mice, and the level of APP and proteolytic products of APP (sAPPα, C99, C83 and Aβ) was measured by western blotting. Treatment of the cells with heparin or enoxaparin had no significant effect on the level of total APP. However, both GAGs decreased the level of C99 and C83, and inhibited sAPPα and Aβ secretion. Heparin also decreased the level of β-secretase (BACE1) and α-secretase (ADAM10). In contrast, heparin had no effect on the level of ADAM17.Conclusions/SignificanceThe data indicate that heparin and enoxaparin decrease APP processing via both α- and β-secretase pathways. The possibility that GAGs may be beneficial for the treatment of AD needs further study.

Huntingtin associated protein 1 regulates trafficking of the amyloid precursor protein and modulates amyloid beta levels in neurons

“…Primary cortical neurons of postnatal day 1 HAP1+/+ (wild type) and HAP1−/−(knockout) litter mates from mice crossed between HAP1+/− were grown on glass coverslips coated with poly‐ d ‐lysine (Sigma, St Louis, MO, USA) as described previously (Hilgenberg and Smith 2007; Cui et al. 2011).…”

“…Immunocytochemical and immunohistochemical staining and fluorescence microscopy Primary cortical neurons of postnatal day 1 HAP1+/+ (wild type) and HAP1)/)(knockout) litter mates from mice crossed between HAP1+/) were grown on glass coverslips coated with poly-D-lysine (Sigma, St Louis, MO, USA) as described previously (Hilgenberg and Smith 2007;Cui et al 2011). 6 days after seeding, neurons were fixed with 4% paraformaldehyde solution in phosphate-buffered saline; Frozen sections of human brain were immersed in the citronic anhydride solution (0.05%, pH7.4) and incubated at 26°C for 1 week.…”

Dendritic Polyglycerol Sulfate Inhibits Microglial Activation and Reduces Hippocampal CA1 Dendritic Spine Morphology Deficits

“…23 Other polysulfates, for example, heparin and enoxaparin, have been proposed as candidates for the diagnosis or treatment of Alzheimer's disease, as they have already been shown to decrease amyloid precursor protein (APP) processing via α-and β-secretase pathways in cell cultures. 24 Microglia, parenchymal tissue macrophages, which constitute about 10% of cells in the central nervous system (CNS), 25 are often named "sensors of the CNS" because they are the first to respond to an insult. 26,27 Microglia modulate neural circuits by facilitating, maintaining, or inhibiting their physiological functions, thus, acting as "bad cop" or "good cop".…”

Modulation of BACE1 Activity as a Potential Therapeutic Strategy for Treating Alzheimer’s Disease

“…Interestingly, secretion of full length APP was also increased following treatment with heparin, and this effect could be blocked by low molecular weight heparin mimetics [138,139]. Conversely, heparin, and a low molecular weight heparin analogue, enoxaparin, have also been shown to inhibit BACE1 processing of APP through a dose-dependent decrease in sAPPβ secretion as well as C99 production [140]. However, the effect of GAGs on BACE1 appears to be more complex than merely an effect on activity, as heparin and enoxaparin were found to decrease BACE1 protein levels in a dose-dependent manner.…”

“…Conversely, heparin, and a low molecular weight heparin analogue, enoxaparin, have also been shown to inhibit BACE1 processing of APP through a dose-dependent decrease in sAPPβ secretion as well as C99 production [140]. Further this effect was not specific for BACE1, as levels of ADAM10, the most likely α -secretase candidate, were also decreased following GAG administration, along with α-secretase related APP processing products, indicating that administration of GAGs interferes with general processing of APP [140]. Further this effect was not specific for BACE1, as levels of ADAM10, the most likely α -secretase candidate, were also decreased following GAG administration, along with α-secretase related APP processing products, indicating that administration of GAGs interferes with general processing of APP [140].…”