Novel roles for the radial spoke head protein 9 in neural and neurosensory cilia.

PubMed ID: 27687975

Author(s): Sedykh I, TeSlaa JJ, Tatarsky RL, Keller AN, Toops KA, Lakkaraju A, Nyholm MK, Wolman MA, Grinblat Y. Novel roles for the radial spoke head protein 9 in neural and neurosensory cilia. Sci Rep. 2016 Sep 30;6:34437. doi: 10.1038/srep34437. PMID 27687975

Journal: Scientific Reports, Volume 6, Sep 2016

Cilia are cell surface organelles with key roles in a range of cellular processes, including generation of fluid flow by motile cilia. The axonemes of motile cilia and immotile kinocilia contain 9 peripheral microtubule doublets, a central microtubule pair, and 9 connecting radial spokes. Aberrant radial spoke components RSPH1, 3, 4a and 9 have been linked with primary ciliary dyskinesia (PCD), a disorder characterized by ciliary dysmotility; yet, radial spoke functions remain unclear. Here we show that zebrafish Rsph9 is expressed in cells bearing motile cilia and kinocilia, and localizes to both 9 + 2 and 9 + 0 ciliary axonemes. Using CRISPR mutagenesis, we show that rsph9 is required for motility of presumptive 9 + 2 olfactory cilia and, unexpectedly, 9 + 0 neural cilia. rsph9 is also required for the structural integrity of 9 + 2 and 9 + 0 ciliary axonemes. rsph9 mutant larvae exhibit reduced initiation of the acoustic startle response consistent with hearing impairment, suggesting a novel role for Rsph9 in the kinocilia of the inner ear and/or lateral line neuromasts. These data identify novel roles for Rsph9 in 9 + 0 motile cilia and in sensory kinocilia, and establish a useful zebrafish PCD model.