Localization and expression of clarin-1, the Clrn1 gene product, in auditory hair cells and photoreceptors

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• 作者：Marisa Zallocchi ; Daniel T. Meehan ; Duane Delimont ; Charles Askew ; Suneetha Garige ; Michael Anne Gratton ; Christie A. Rothermund-Franklin ; Dominic Cosgrove
• 关键词：Usher syndrome ; Clarin-1 ; Stereocilia ; Connecting cilia ; Ribbon synapse
• 刊名：Hearing Research
• 出版年：2009
• 出版时间：September 2009
• 年：2009
• 卷：255
• 期：1-2
• 页码：109-120
• 全文大小：914 K

文摘

The Usher syndrome 3A (CLRN1) gene encodes clarin-1, which is a member of the tetraspanin family of transmembrane proteins. Although identified more than 6 years ago, little is known about its localization or function in the eye and ear. We developed a polyclonal antibody that react with all clarin-1 isoforms and used it to characterize protein expression in cochlea and retina. In the cochlea, we observe clarin-1expression in the stereocilia of P0 mice, and in synaptic terminals present at the base of the auditory hair cells from E18 to P6. In the retina, clarin-1 localizes to the connecting cilia, inner segment of photoreceptors and to the ribbon synapses. RT-PCR from P0 cochlea and P28 retina show mRNAs encoding only isoforms 2 and 3. Western blots show that only isoform 2 is present in protein extracts from these same tissues. We examined clarin-1 expression in the immortomouse-derived hair cell line UB/OC-1. Only isoform 2 is expressed in UB/OC-1 at both mRNA and protein levels, suggesting this isoform is biologically relevant to hair cell function. The protein co-localizes with microtubules and post-transgolgi vesicles. The subcellular localization of clarin-1 in hair cells and photoreceptors suggests it functions at both the basal and apical poles of neurosensoriepithelia.