Figure 3.

TREM2 deletion in microglia leads to cell cycle arrest at the G₁/S checkpoint. A, Trem2^{−/ −}or WT microglia were fixed, stained with DAPI, and analyzed by flow cytometry. B, Ratio of stage-specific (G₁/G₀, S, or G₂/M) cell numbers to total cell numbers was quantified for comparison. The number of G₁/G₀ phase cells increased, whereas S-phase cells decreased in Trem2^−/− microglia compared with WT microglia. C, Cyclin D1 and c-Myc mRNA levels were decreased in Trem2^−/− microglia compared with WT cells as quantified by qRT-PCR. D, Cell lysates from Trem2^−/− microglia were analyzed for Cyclin D1 and c-Myc by Western blotting. Protein levels were quantified by densitometry normalized to α-tubulin. Note that Cyclin D1 and c-Myc were downregulated in Trem2^−/− microglia compared with WT cells. Data are plotted as mean ± SEM (n = 3). *p < 0.05; **p < 0.01; ***p < 0.001.