1. FGFR1-mediated protocadherin-15 loading mediates cargo specificity during intraflagellar transport in inner ear hair-cell kinocilia
- Author
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Shigenobu Yonemura, Kazuyo Misaki, John E. Ladbury, Raj K. Ladher, Shri Vidhya Seshadri, Akira Honda, Guy P. Richardson, Tomoko Kita, and Zamal Ahmed
- Subjects
0301 basic medicine ,Stereocilia (inner ear) ,Cadherin Related Proteins ,Chick Embryo ,Transport Pathway ,Mice ,03 medical and health sciences ,Intraflagellar transport ,Ciliogenesis ,otorhinolaryngologic diseases ,medicine ,Animals ,Inner ear ,Receptor, Fibroblast Growth Factor, Type 1 ,Phosphorylation ,Protein Precursors ,Adaptor Proteins, Signal Transducing ,Hair Cells, Auditory, Inner ,Multidisciplinary ,integumentary system ,Chemistry ,Cilium ,Biological Sciences ,Kinocilium ,Cadherins ,Clathrin ,Cell biology ,Adaptor Proteins, Vesicular Transport ,Protein Transport ,030104 developmental biology ,medicine.anatomical_structure ,Flagella ,sense organs ,Hair cell ,Apoptosis Regulatory Proteins - Abstract
The mechanosensory hair cells of the inner ear are required for hearing and balance and have a distinctive apical structure, the hair bundle, that converts mechanical stimuli into electrical signals. This structure comprises a single cilium, the kinocilium, lying adjacent to an ensemble of actin-based projections known as stereocilia. Hair bundle polarity depends on kinociliary protocadherin-15 (Pcdh15) localization. Protocadherin-15 is found only in hair-cell kinocilia, and is not localized to the primary cilia of adjacent supporting cells. Thus, Pcdh15 must be specifically targeted and trafficked into the hair-cell kinocilium. Here we show that kinocilial Pcdh15 trafficking relies on cell type-specific coupling to the generic intraflagellar transport (IFT) transport mechanism. We uncover a role for fibroblast growth factor receptor 1 (FGFR1) in loading Pcdh15 onto kinociliary transport particles in hair cells. We find that on activation, FGFR1 binds and phosphorylates Pcdh15. Moreover, we find a previously uncharacterized role for clathrin in coupling this kinocilia-specific cargo with the anterograde IFT-B complex through the adaptor, DAB2. Our results identify a modified ciliary transport pathway used for Pcdh15 transport into the cilium of the inner ear hair cell and coordinated by FGFR1 activity.
- Published
- 2018
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