Figure 5.
IPCs exit cell cycle prematurely in the absence of Gli3. A–C, Cell cycle exit was studied by labeling cells in the S-phase of cell cycle with EdU and BrdU at E14.5 and E15.5, respectively, and analyzed for coexpression of EdU (green), BrdU (blue), and Ki67 (red) at E16.5. Boxed areas of CP and SVZ are shown at higher magnification (right) to indicate cells remaining in cell cycle from E14.5 to E16.5 (EdU+ BrdU+ Ki67+, white dashed outline and arrowheads), cells that exited cell cycle by E15.5 (EdU+ BrdU− Ki67−, green dashed outline), and cells that exited cell cycle by E16.5 (BrdU+ Ki67−, yellow dashed outline). Note that more EdU+ cells are found in the CP in Gli3cko than in controls. D, Cells that were dividing at E14.5 (EdU+) were quantitatively analyzed at E16.5 for their cell cycle status. A higher percentage of EdU+ became postmitotic by E15.5 (EdU+ BrdU− Ki67−, green) in Gli3cko than in controls (Con). Similarly, more mutant (Mut) cells exited cell cycle by E16.5 (EdU+ BrdU+ Ki67−, blue) compared with controls. In contrast, there was a decrease in the number of EdU+ cells remaining in cell cycle by E16.5 (EdU+ BrdU− Ki67+, yellow; EdU+ BrdU+ Ki67+, white). E, Cells dividing at E15.5 (BrdU+) also increased the cell cycle exit by E16.5, as evidenced by the ratio of BrdU+ Ki67− cells to the total number of BrdU+ cells. F, More EdU+ cells were found to be postmitotic in the CP of Gli3cko compared with the control. N = 3 per genotype for E14.5-dividing cell analysis. N = 8 per genotype for E15.5-dividing cell analysis. Error bars represent the SD.