Conditional Plk4 expression and CA in the developing mouse kidney. (A) Schematic representation of nephrogenesis, from renal progenitors to mature nephrons. Diagram highlights the progenitor cell type and nephron segment-specific expression of Plk4 mediated by Six2-Cre (brown), Hoxb7-Cre (blue), and Ksp-Cre (dots). (B) Kidney sections from E15.5 control, Hoxb7-Plk4 (top), and Six2-Plk4 (bottom) mice were immunostained with antibodies targeting mCherry (Plk4), γ-tubulin (centrosomes), E-cadherin (UB tubules), or Six2 (MM). Control kidneys lacking mChPlk4 mainly contain one centrosome with one to two foci. In Hoxb7-Plk4, excess centrosomes are seen specifically in regions of UB tubules overexpressing mChPlk4 (white box, magnified 1.5-fold). Importantly, adjacent cells within the same tubule that lack mChPlk4 signal display normal centrosome doublets (arrowheads). Nuclei were stained with DAPI. Similarly, supernumerary centrosomes were seen specifically in cells overexpressing mChPlk4 in Six2-Plk4 mice (white box, magnified 1.5-fold). Nuclei were stained with DAPI. Bars (insets), 2 µm. (C) Graphs show the percentage of cells with normal centrosome number (one or two) or CA (more than two centrosomes) in Hoxb7-Plk4 or Six2-Plk4 mice. Centrosome number was quantified per nucleus of the cells in each progenitor population, using cell-specific markers (E-cadherin or Six2). n = 1,210 cells (E15.5 WT control), 324 mChPlk4-positive cells (E15.5 Hoxb7-Plk4), 1,442 cells (E15.5 WT control), and 277 mChPlk4-positive cells (E15.5 Six2-Plk4). Box plots represent the median, maximum, and minimum values for each dataset. A two-tailed unpaired t test was performed to determine statistically significant differences between samples (*, P < 0.05).