Figure 3. Wdr62 and Aspm genetically interact to control centriole duplication.

(A) Mouse embryonic fibroblasts (MEFs) stained with Centrin (green) and Cyclin A (red) to mark centrioles and S-phase/G2 cells, respectively, showing that loss of Wdr62, Aspm or both leads to underduplication of centrioles. Left to right: Wild-type (WT), Wdr62 −/−, Aspm −/−, Wdr62 +/−, Aspm +/−, Wdr62 +/−; Aspm −/−. Insets (in grayscale) show Centrin staining at higher magnification. Scale bar = 10 µm.

(B) EM of representative WT (left), Aspm −/− (middle) and Wdr62 −/− (right) MEFs, with white dotted ovals or circles outlining the individual centrioles. Pairs of centrioles are seen in WT MEFs, while only one unpaired centriole is visible in Aspm −/− and Wdr62 −/− MEFs. Scale bar = 100 nm.

(C) Serial EM confirms centriole duplication defect in Wdr62 +/−; Aspm −/− mouse embryonic fibroblasts (MEFs). Left: White rectangles and circles outline the pair of centrioles in serial sections of a representative WT cell. Right: Only one centriole (outlined in white) is visible through several serial sections of a representative Wdr62 +/−; Aspm −/− cell. Scale bar = 20 nm.

(D) Quantification of centriole number in S-phase cells of various genotypes indicates that the severity of the centriole duplication defect is proportional to the severity of the microcephaly phenotype. N = 200–300 cells per genotype. Fisher’s exact test, “ns” = not significant, * = p < 0.05 and **** = p < 0.0001 (compared to WT unless otherwise indicated). See also Supplemental Figure S3.