UDP-Induced Phagocytosis and ATP-Stimulated Chemotactic Migration Are Impaired in STIM1^−/− Microglia In Vitro and In Vivo

Figure 6

Decreased neuron phagoptosis activity of STIM1^−/− microglia. (a) Neuron phagoptosis by WT microglia was shown by immunostaining of neuron and microglia after damaging neuron and LPS-activated WT microglia (bar = 200 μm). Normal neurons were stained with MAP specific antibodies (green), and WT microglia were stained with tomato lectins (red). The second image shows enlarged microglia indicated via arrows. The third image shows highly magnified images of the activated microglia engulfing neurons, so MAP staining was found inside of the microglia stained with tomato lectin. (b) Similar image to the above, but used LPS-activated STIM1^−/− microglia which coexisted with neurons. The second image shows some enlarged STIM1^−/− microglia indicated with arrows. The third image shows highly magnified images showing the activated microglia near the neurons. (c) The relative size of the activated WT and STIM1^−/− microglia indicated via bar graph. 25 μm² was determined as the minimum size of activated microglia, and the number of cells bigger than 35 μm² was assigned as the “fully enlarged microglia engulfing neuron,” which is significantly small in STIM1^−/− microglia population. . ; = cell number from 3 independent experiments. (d) The relative neuron survival rate was analysed using MAP2 staining intensity of the remaining neuron after 6 hr phagoptosis, in which images were delivered from five randomly selected fields of leftmost images. Each of the phagoptosis activities was compared with the total MAP2 intensity of the only neuron which was without phagoptosis by activated microglia. , , , and images from 3 independent experiments.

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