FIGURE 4.

AIMP3 induces cell cycle arrest at G2/M phase and apoptosis depends on p53. A, Cell cycle analysis of A549 cells transfected with different amounts of AIMP3 for 48 h. Cells were collected and analysed by flow cytometry after propidium iodide staining. The inserts showed the proportion of cells for each phase and were marked with different colours (violet: G0/G1 phase, green: S phase and gold: G2/M phase). B, The quantification of cell number in each phase of cell cycle. C, Examination of apoptotic cells in A549 cells transfected with indicated amount of AIMP3. D, Quantitative analysis of the percentage of apoptotic cells was shown in Figure C. Data are presented as mean ± SEM (n = 3); * P < .05, ** P < .01. E, The effect of AIMP3 on p53‐dependent transcription of NOXA, PUMA and p21. A549 cells were transiently transfected with indicated amount of AIMP3 and incubated for 24 h. Total RNAs were extracted and used for RT‐PCR detection. F, A549 cells were co‐transfected with p21 promoter‐reporter vector and different amounts of AIMP3 expression plasmid (0, 50, 100 ng). Relative luciferase activity values are presented as mean ± SEM (n = 3); ** P < .01 by Student's t test. G, A549 cells were transiently transfected with HA‐AIMP3 for 24 h, and whole cell lysates were immunoprecipitated with HA antibody (mouse) or mouse IgG as control. The precipitates were immunoblotted with ATM antibody. H, Cells were transiently transfected with AIMP3 or control vector. The expression of indicated proteins was analysed by Western blot