FIGURE 5.

Roles of extracellular signal-regulated kinase (ERK) activity in regulating microglial phagocytosis of fibrillar Aβ42 and of neuronal phagocytosis. (a) Flow cytometry experimental data showing the uptake of fluorescent Aβ42 fibrils by live CD45+ microglia that had been treated with an ERK1/2 inhibitor and/or IFNγ. (b) Dotplots showing the reduction of microglial phagocytosis of Aβ42 by ERK inhibition under unstimulated and stimulated conditions in-vitro. N = 3 replicates per group. Error bars represent SD. *p < 0.05, ^**p < 0.01, ^***p < 0.005. (c) Experimental protocol for microglia-N2a coculture study: GFP-positive N2a cells were differentiated for 4 days using retinoic acid. Meanwhile, primary microglia were isolated, and after 24 hr, were incubated with the ERK inhibitor with or without IFNγ. After incubation for 24 hr, the microglia were seeded into the differentiated N2a cultures overnight and then harvested for antibody staining and flow cytometry. This figure was created using modified images from Servier Medical Art. (d) Bar plot demonstrating the viability of N2a cells when cocultured with microglia. N = 3 replicates per group. Error bars represent SD. *p < 0.05, ^**p < 0.01, ^***p < 0.005. (e) Bar plots showing a reduction of microglialphagocytosis of differentiated N2a cells in the ERK inhibited group. GFP⁺ N2A cells were differentiated and then cocultured with primary microglia that were pretreated with an ERK inhibitor with or without IFNγ. N = 3 replicates per group. Error bars represent SD. *p < 0.05, ^**p < 0.01, ^***p < 0.005