Figure 3.

Zn-finger domain of MdmX suppresses genome instability in mouse tumor cells. (a) DNA content of MdmX/p53-double knockout (DKO) mouse tumor cells transduced with MdmX FL or deletion mutants determined by propidium iodide staining. DNA content of experimental cells (red histograms) was superimposed over the DNA content of parental non-transduced MdmX/p53-null cells (blue histograms). (b) Metaphase spread analysis for chromosome number per cell (in indicated ranges) in MdmX-transduced DKO cells. The results are from representative experiment with at least 50 metaphase cells scored per cell line. (c) Summary of chromosome analyses showing cell fraction with larger than triploid genome in population of transduced DKO cells. Error bars represent mean±s.d. from two to four independent experiments with more than 50 metaphase cells scored per cell line per experiment. (d) Frequency of multipolar spindles as a percent of total mitotic events in the populations of MdmX-transduced DKO cells. More than 200 mitotic spindles were scored per experiment. Error bars represent mean±s.d. from three independent experiments. (e) Representative imunofluorescence images of DKO cells illustrating mitotic spindle organization. Cells were stained for alpha-tubulin (green), gamma-tubulin (red) and DNA (4′-6-diamidino-2-phenylindole, blue). Scale bar, 10 μm. (f) Chromosome analyses showing cell fraction with larger than triploid genome in population of MdmX-transduced MdmX/Mdm2/p53-triple knockout (TKO) mouse tumor cells. Error bars represent mean±s.d. from two independent experiments with at least 50 metaphases scored per cell line per experiment. (g) Frequency of multipolar spindles expressed as a percent of total mitotic events in the populations of transduced TKO cells. Error bars represent mean±s.d. from two to three independent experiments. P-values relative to Mock control: **P<0.005; *P from 0.005 to 0.05, unpaired t-test.