Fig. 2.

Cep57 is essential for centriole engagement and PCM organization in mitosis. a HeLa cells were treated with siControl or siCep57 and immunostained with antibodies against centrin-2 (green) and Cep192 (red). Left–right arrows indicate precociously disengaged centrioles. b Schematic model of the phenotype of Cep57 knockdown observed in a. Depletion of Cep57 led to PCM disorganization and precocious centriole disengagement. c Histograms represent frequency of mitotic cells with the indicated phenotypes observed in a. Values are mean percentages ± s.d. from three independent experiments (n = 50 for each experiment). d Time-lapse observation of cells upon Cep57 depletion. HeLa cells expressing GFP-centrin-1 were treated with siControl or siCep57 and observed in the presence of SiR-DNA (200 nM). Green and blue represent GFP-centrin-1 and DNA, respectively. Left–right arrows indicate precociously disengaged centrioles. Time zero corresponds to the beginning of nuclear envelope breakdown (NEBD). e Time-lapse observation of unequal distribution of centrioles (UDC) in Cep57-depleted cells. Precociously disengaged centrioles move around in the cells, which sometimes results in UDC. Arrowheads indicate the precociously disengaged centriole moving toward the opposite spindle pole. f Histograms represent frequency of the cells with the indicated phenotypes observed in e. Values are mean percentages ± s.d. from three independent experiments (siControl n = 116, siCep57 n = 119). g Aberrant acquisition of PCM components of precociously disengaged daughter centrioles in Cep57-depleted cells. HeLa cells were immunostained with the indicated antibodies h Ectopic MTOC activity of precociously disengaged daughter centrioles in Cep57-depleted cells. HeLa cells were immunostained with antibodies against α-Tubulin (green) and CP110 (red). Arrowheads indicate the aberrant MTOC activity in Cep57-depleted mitotic cells. i Schematic illustration of the phenotype of Cep57 knockdown observed in g and h. Precociously disengaged daughter centrioles aberrantly acquire PCM components and MTOC activity. All scale bars, 5 μm in the low-magnified view, 1 μm in the inset. Two-tailed, unpaired Student’s t-test was used in c and f to obtain p value. **p < 0.01