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Le Wang, Junhuang Zou, Zuolian Shen, Jun Yang; Interaction Of Whirlin And Espin Provides A Potential Link Between The Ush2 Complex And Actin Filaments. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2662.
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Whirlin, USH2A and VLGR1 are the three causative genes of Usher syndrome type II (USH2), a condition with both retinitis pigmentosa and congenital deafness. The proteins encoded by these genes form a complex in photoreceptors. Disruption of this complex causes retinal degeneration. However, the composition and function of this complex are largely unknown. In this study, we identified a new component of this complex.
A yeast two-hybrid screen of a mouse retinal cDNA library was conducted using whirlin as a bait. The obtained whirlin-interacting candidate proteins were further examined by a series of biochemical and cellular assays in cultured cells, photoreceptors, and hair cells.
Espin, an actin-binding and -bundling protein, was identified as a whirlin-interacting candidate by the yeast two-hybrid screen. The interaction between whirlin and espin was further confirmed by coimmunoprecipitation and colocalization in cultured cells. This interaction was shown to be mediated through the multiple domains in espin and in whirlin. In the retina, whirlin and espin was coimmunoprecipitated. In both photoreceptors and hair cells, these two proteins exhibited partial colocalization. The expression of espin was decreased in whirlin knockout hair cells.
This study demonstrates that espin is a novel component of the USH2 complex in both photoreceptors and hair cells. Based on the actin-binding and -bundling ability of espin, the interaction between whirlin and espin suggests that the USH2 complex may associate with actin filaments in cells. This interaction probably plays a more important role in hair cells than in photoreceptors.
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