The asymmetric hair bundle on top of hair cells (HCs), comprises a kinocilium and stereocilia staircase, dictates HC's directional sensitivity. The mother centriole (MC) forms the base of the kinocilium, where stereocilia are subsequently built next to it. Previously we showed that transcription factor Emx2 reverses hair bundle orientation and its expression in the mouse vestibular utricle is restricted, resulting in two regions of opposite bundle orientation (Jiang et al, 2017). Here, we investigated establishment of opposite bundle orientation in embryonic utricles by live-imaging GFP-labeled centrioles in HCs. The daughter centriole invariably migrated ahead of the MC from the center to their respective peripheral locations in HCs. Comparing HCs between utricular regions, centriole trajectories were similar but they migrated towards opposite directions, suggesting that Emx2 pre-patterned HCs prior to centriole migration. Ectopic Emx2, however, reversed centriole trajectory within hours during a critical time-window when centriole trajectory was responsive to Emx2.
The following figures contain the source data files. Figure 2 (source data 1), Figure 2 supplement 2 (source data 1-3), Figure 2 supplement 3 (source data 1-4), Figure 2 supplement 4 (source data 1-2), Figure 3 (source data 1-2), figure 3 supplement 2 (source data 1), Figure 4 (source data 1-2), Figure 5 (source data 1), Figure 6 (source data 1-2), Figure 7 (source data 1), Figure 7 supplement 1 (source data 1), Figure 8 (source data 1-2), Figure 9 (source data 1).
- Yosuke Tona
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All animal experiments were conducted according to NIH guidelines and under the approved Animal Care Protocol of NIDCD/NIH (#1212-17).
- Tanya T Whitfield, University of Sheffield, United Kingdom
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