Figure 3.

Heparin inhibits LRP1-mediated cellular uptake of Aβ in N2a cells. A, N2a cells stably expressing a LRP1 minireceptor (N2a–mLRP4) or vector control (N2a–pcDNA3) were analyzed for LRP1 expression using an anti-LRP1 antibody. B, C, N2a–pcDNA3 or N2a–mLRP4 cells were incubated with FAM–Aβ₄₀ (500 nm; B) or FAM–Aβ₄₂ (500 nm; C), respectively, in the presence or absence of heparin (15 U/ml = ∼100 μg/ml) for 24 h at 37°C. Internalization of Aβ was analyzed by FACS. C, In some experiments, cells were treated with Heparinase I (Hep. I). D, Various concentrations of heparin (0.15 mU/ml to 15 U/ml) were incubated with N2a–pcDNA3 (open circles) and N2a–mLRP4 (filled circles) cells during their incubation with FAM–Aβ₄₂ (500 nm). Error bars indicate SD from three independent experiments. **p < 0.01. E, Internalization of FAM–Aβ₄₂ (500 nm) was analyzed by confocal microscopy. Left, middle, and right columns indicate FAM–Aβ₄₂, Lysotracker, and merged images, respectively.