FIGURE 6.

Short term treatment of microglia with LPS up-regulates P2X4 expression at the cell surface. A, surface biotinylation was carried out on microglia incubated with LPS (0.5 μg/ml) for different time periods. Samples were loaded to obtain approximately the same level of total P2X4 protein for the different treatments, along with the corresponding fractions of streptavidin-purified protein. After 3 h in LPS, there was a significant increase in the fraction of biotinylated protein (*, p < 0.05, n = 3). B, after 3 h in LPS (0.5 μg/ml) there was a small but significant increase in total P2X4 protein, normalized to actin (*, p < 0.05, n = 3). C, microglia were treated with a combination of LPS and Dynasore, and total protein samples were loaded to obtain approximately the same level of actin. Co-treatment with Dynasore and LPS resulted in a dramatic increase in total P2X4 expression (*, p < 0.05). Blots for biotinylated samples are not shown because cells became permeabilized following the combined Dynasore/LPS treatment.