FIGURE 1.

Co-expression of DAP12 with TREM2 increases the level of TREM2-CTF. A, HEK293T cells were transfected with TREM2-Myc in combination with vector control or DAP12-GFP. Cells were harvested 24 h after transfection and the lysates were analyzed by Western blotting. The levels of TREM2 and DAP12 were detected by antibodies against the Myc or GFP epitope, respectively. Blots with α-Tubulin in this and subsequent figures serve as loading controls. Bar graph to the right shows the quantification of Western blots as ratios of TREM2-CTF/FL (n = 4). **, p < 0.01. B, HEK293T cells were transfected with TREM2-GFP in combination with vector control or DAP12-Myc. Cell surface proteins were biotinylated with sulfo-NHS-biotin followed by precipitation with streptavidin beads. Biotinylated proteins were eluted with SDS-PAGE sample buffer and subjected to Western blotting. Bar graphs to the right show the quantification of Western blots as either relative levels of TREM2-FL or TREM2-CTF/TREM2-FL ratios on the cell surface (n = 3). ns, not significant; ***, p < 0.001. C, BV2 cells were transfected with TREM2-Myc in combination with vector control or DAP12-GFP. Cell lysates were collected at 24 h post-transfection. The levels of TREM2 and DPAP12 were detected by antibodies against Myc or GFP epitope, respectively. Bar graph to the right shows the quantification of Western blots as ratios of TREM2-CTF/TREM2-FL (n = 3). **, p < 0.01.