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XB-ART-1469
Proc Natl Acad Sci U S A August 30, 2005; 102 (35): 12572-7.
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Xenopus TRPN1 (NOMPC) localizes to microtubule-based cilia in epithelial cells, including inner-ear hair cells.

Shin JB , Adams D , Paukert M , Siba M , Sidi S , Levin M , Gillespie PG , Gründer S .


Abstract
In vertebrates, the senses of hearing and balance depend on hair cells, which transduce sounds with their hair bundles, containing actin-based stereocilia and microtubule-based kinocilia. A longstanding question in auditory science is the identity of the mechanically sensitive transduction channel of hair cells, thought to be localized at the tips of their stereocilia. Experiments in zebrafish implicated the transient receptor potential (TRP) channel NOMPC (drTRPN1) in this role; TRPN1 is absent from the genomes of higher vertebrates, however, and has not been localized in hair cells. Another candidate for the transduction channel, TRPA1, apparently is required for transduction in mammalian and nonmammalian vertebrates. This discrepancy raises the question of the relative contribution of TRPN1 and TRPA1 to transduction in nonmammalian vertebrates. To address this question, we cloned the TRPN1 ortholog from the amphibian Xenopus laevis, generated an antibody against the protein, and determined the protein''s cellular and subcellular localization. We found that TRPN1 is prominently located in lateral-line hair cells, auditory hair cells, and ciliated epidermal cells of developing Xenopus embryos. In ciliated epidermal cells TRPN1 staining was enriched at the tips and bases of the cilia. In saccular hair cells, TRPN1 was located prominently in the kinocilial bulb, a component of the mechanosensory hair bundles. Moreover, we observed redistribution of TRPN1 upon treatment of hair cells with calcium chelators, which disrupts the transduction apparatus. This result suggests that although TRPN1 is unlikely to be the transduction channel of stereocilia, it plays an essential role, functionally related to transduction, in the kinocilium.

PubMed ID: 16116094
PMC ID: PMC1194908
Article link: Proc Natl Acad Sci U S A
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: actb actl6a ank1 cdh23 mcoln3 naa50 nos1 pkd2 trpa1 trpc1 trpc3 trpm2 trpm3 trpv1 trpv4 tuba4b XB5813854 [provisional:ankrd52]
Antibodies: FITC-phalloidin Lectin FM1-43 TRPN1 Ab1 cdh23 Ab1


Article Images: [+] show captions
References [+] :
Adams, Biotin amplification of biotin and horseradish peroxidase signals in histochemical stains. 1992, Pubmed