Study on a cause of hearing defect in Vlgr1 mutated mice

1)Vlgr 1功能域的研究我们与法国人小组合作研究了这一主题。2）Vlgr 1基因敲除小鼠听力障碍的研究通过听性脑干反应和畸变产物耳声发射检测，发现Vlgr 1基因敲除小鼠因内耳功能障碍而出现听力障碍。Vlgr 1的表达在胚胎第17天至出生后第10天的发育中的毛细胞中被鉴定。共聚焦显微镜下Vlgr 1定位于毛细胞静纤毛基部。这种Vlgr 1定位仅限于从毛细胞的顶面约200-400 nm内的静纤毛的基础上，使用免疫电镜。在无钙条件下，Vlgr 1的这种定位消失。扫描电镜下可见Vlgr 1基因敲除小鼠耳蜗毛细胞静纤毛畸形。出生后第0天，Vlgr 1基因敲除小鼠的毛束外观几乎正常。Vlgr 1基因敲除小鼠的耳蜗毛束在出生后第8天变得紊乱。此外，Vlgr 1基因敲除小鼠的静纤毛变得倾斜和紊乱。这些结果表明Vlgr 1基因缺失导致静纤毛发育异常，Vlgr 1基因缺失与踝关节连接的形成有关。

1) Study on the functional domain of Vlgr1We collaborated on this theme with the group of French. We revealed that Vlgr1 was related to the proteins that consist of the ankle link of stereocilia.2) Study on the hearing defect of Vlgr1 knockout miceWe revealed that Vlgr1-knockout mice suffered from a hearing defect because of inner ear dysfunction, as indicated by auditory brainstem response and distortion product oto-acoustic emissions. The expression of Vlgr1 was identified in the developing hair cells from embryonic day 17 to postnatal day 10. Vlgr1 was localized in the base of stereocilia on hair cells using confocal microscopy. This Vlgr1 localization was limited to the base of stereocilia within approximately 200-400 nm from the apical surface of hair cells using immunoelectron microscopy. This localization of Vlgr1 was disappeared under the calcium free condition. Under the SEM studies, the Vlgr1 knockout mice showed malformation of the stereocilia of cochlear hair cells. At postnatal day 0, the appearance of hair bundles was almost normal in the Vlgr1 knockout mice. The cochlear hair bundles of Vlgr1 knockout mice became disarranged at postnatal day 8. Furthermore, the stereocilia in the Vlgr1 knockout mice became slanted and disarranged thereafter. These results indicate that loss of Vlgr1 resulted in abnormal development of stereocilia formation and the Vlgr1 was related to the formation of ankle link.