Figure 4.

Neurite protective effect of Siglec-E in neuron–microglia cocultures. A, Loss of neurites after knockdown of Siglece in microglia. Neurons were cocultured for 48 h with microglia. Siglece overexpression increased whereas knockdown of Siglece decreased the relative neurite length. Representative images without sialidase treatment of three independent experiments are shown. Scale bar, 30 μm. B, Relative neurite length and neuronal cell body density were quantified. Although the neuronal cell body density was unchanged (right graph), the relative neurite length was dependent on the expression level of Siglec-E on the microglial surface (left graph). After sialidase treatment, the relative neurite length was significantly reduced. **p ≤ 0.01, ***p ≤ 0.001. C, Neurons were cocultured with microglia in the presence of Trolox. Reduced neurite length after knockdown of Siglec-E was restored after treatment with 40 nm Trolox. ***p ≤ 0.001.