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Stereocilin Paralogs Have Distinct Roles in Zebrafish Inner Ear Development
Author(s) -
Kramer Kenneth L,
Inserra Christopher J
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.740.23
Subject(s) - kinocilium , stereocilia (inner ear) , cilium , inner ear , biology , zebrafish , microbiology and biotechnology , hair cell , anatomy , basal body , utricle , aurelia aurita , microtubule , genetics , flagellum , jellyfish , gene , ecology
In the vertebrate inner ear, sound and movement are transduced into electrical signals by specialized bundles of cilia on the apical surface of sensory hair cells. Each hair bundle is composed of a single Tubulin‐filled kinocilium attached to multiple rows of Actin‐packed stereocilia. Cilia are linked to each other and to an overlying membrane by a complex of proteins that includes Stereocilin (STRC), a putative GPI‐linked protein that is expressed in both stereocilia and kinocilia in mouse auditory and vestibular hair cells. Since loss of STRC in mouse results in defects in the attachments both between neighboring cilia as well as between cilia and the overlying tectorial membrane, we sought to determine if STRC is similarly required in zebrafish inner ear development. We generated antibodies that specifically distinguish the two zebrafish STRC paralogs and found that STRCa and STRCb are both expressed during hair cell formation but with slightly different expression patterns. STRCb is found on the distal tip of kinocilia when the hair cells first start tethering to the seeding otoliths, while STRCa is found a few hours later in a few punctate locations along the distal half of the kinocilium. Knockdown of strcb by injecting antisense morpholinos or eliminating strcb in CRISPR/Cas9‐generated mutant embryos blocked the ability of kinocilia to tether otoliths to hair cells. In contrast, otolith attachment appeared to be normal in strca morphants and mutant embryos. Kinocilia in strcb morphant and mutant embryos were normal in length, yet proteins in the unattached otolith were disorganized compared to otoliths in normal and strca ‐deficient zebrafish. We conclude that STRCb is uniquely required for zebrafish otolith attachment and organization. Support or Funding Information The work was supported by grants from the National Institutes of Health (8P20GM103471) and the Creighton Health Science Strategic Investment Fund.