Figure 3.

TLR3 signaling negatively regulates neural progenitor cell proliferation. A, Treatment of neurospheres with the TLR3 ligands polycytidylic acid (polyIC) (10 or 20 μg/ml) and interferon-β (200 or 500 U) significantly reduced the number of BrdU-positive (proliferating) cells. *p < 0.05 compared with the control value. B, NPC proliferation relative to control values in wild-type neurospheres treated with polyIC (2 or 20 μg/ml) and neurosphere cultures derived from TLR3^−/− mice. Immunofluorescence analysis of differentiated TLR3^−/− neurospheres showing their potential to remain NPCs (C, bottom, sox2, green) or differentiate into astrocytes (C, bottom, GFAP, red), oligodendrocytes (C, top, CNPase, green), or neurons (C, top, β3-tubulin, red). All images counterstained with Hoechst. Scale bar, 100 μm. D, No difference was observed in the percentage of neurons, astrocytes and oligodendrocytes derived from WT or TLR3^−/− (TLR3KO) mice.