Fig. 5.

CSNK2A1 is essential for tip stability. (A) A tip gap is a tip positive for ARL13B and negative for acetylated alpha-tubulin (illustrated by ‘’a’’). (Scale bars, 1 μm.) Graph shows the mean percentage of cilia that display tip gaps ± SEM (47 control cilia and 49 mutant cilia). (B) Under Noco treatment, mutant cilia are less stable than control cilia. Cells were serum starved for 48 h and then treated with 10 μM Noco or dimethyl sulfoxide (DMSO) as a control for 35 min. Cilia length was collected and data were displayed as a mean difference of cilia length [+Noco]−[−Noco] ± SEM. Measurements were produced from 74 control cilia and 70 Csnk2a1 mutant cilia. (C) Csnk2a1-knockout cells shed more ciliary EVs. Western blots from total cell lysates (TCL, left blots) and EVs purifications (right blots) are probed with antibodies to FLOTILLIN-1, ARL13B, and IFT88. For each probe, the fold change value was calculated as follows: ratio of [EVs_Area under the curve]:[TCL_Area under the curve]. The fold change was normalized to the control value. Dashed line marks where the Western blot images were cut to remove experimental conditions that were not relevant to the current study. (D) Csnk2a1-knockout cilia are prone to tip breakage. Nonclonal control and Csnk2a1-depleted cells were generated in transgenic ARL13B-mCherry MEFs. Cilia were imaged every 15 min for 75 min. Breakage events were quantified and normalized to the total number of imaged cilia. The graph represents the mean percentage of tip breakage ± SEM for control (n = 51 cilia) and Csnk2a1-depleted cells (n = 63 cilia). (Scale bars, 3 μm.)