Progressive deafness and altered cochlear innervation in knock-out mice lacking prosaposin
Progressive deafness and altered cochlear innervation in knock-out mice lacking prosaposin
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DOI：
10.1523/jneurosci.3746-06.2006
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发表时间：
2006-12-13
影响因子：
5.3
通讯作者：
Lustig, Lawrence R.
中科院分区：
文献类型：
--
作者：
Akil, Omar;Chang, Jolie;Lustig, Lawrence R.
在酵母双杂交筛选鉴定出鞘脂激活蛋白原作为与烟碱乙酰胆碱受体（nAChR）亚基α 10的潜在相互作用蛋白之后，进行研究以表征正常啮齿动物内耳中的鞘脂激活蛋白原。鞘脂激活蛋白原在出生时表现为弥漫性Corti器官表达，到出生后第21天（P21）逐渐定位于内毛细胞（IHC）及其支持细胞、内柱细胞以及外毛细胞（OHC）和Deiters细胞（DC）的突触区域。显微解剖的OHC和DC定量逆转录酶-PCR和免疫组织学定位于DCs和OHC的鞘脂激活蛋白原mRNA，蛋白质主要位于DCs的顶端。随后对鞘脂激活蛋白原基因敲除（KO）（-/-）小鼠的研究显示，到P19时听力完好但略有下降，但到P25时耳聋，从P15开始畸变产物耳声发射减少。从P12开始，鞘脂激活蛋白原KO小鼠显示组织学Corti器官变化，包括IHC和大上皮嵴区域的细胞肥大、耳蜗尖OHC损失和OHC空泡化。免疫荧光显示，在该地区的IHC和听觉传出神经突起的Corti隧道区域的听觉传入神经突起的过度生长旺盛。来自这些KO小鼠的IHC记录显示正常的I-V曲线和对施加的乙酰胆碱的反应。总之，这些结果表明，saposin有助于维持正常的神经支配模式的器官的Corti。此外，鞘脂激活蛋白原的重叠发育表达模式和对nAChR α 10的结合能力表明，α 10也可能在这一功能中发挥作用。
After a yeast two-hybrid screen identified prosaposin as a potential interacting protein with the nicotinic acetylcholine receptor (nAChR) subunit alpha 10, studies were performed to characterize prosaposin in the normal rodent inner ear. Prosaposin demonstrates diffuse organ of Corti expression at birth, with gradual localization to the inner hair cells (IHCs) and its supporting cells, inner pillar cells, and synaptic region of the outer hair cells (OHCs) and Deiters' cells (DCs) by postnatal day 21 (P21). Microdissected OHC and DC quantitative reverse transcriptase-PCR and immunohistology localizes prosaposin mRNA to DCs and OHCs, and protein predominantly to the apex of the DCs. Subsequent studies in a prosaposin knock-out (KO) (-/-) mouse showed intact but slightly reduced hearing through P19, but deafness by P25 and reduced distortion product otoacoustic emissions from P15 onward. Beginning at P12, the prosaposin KO mice showed histologic organ of Corti changes including cellular hypertrophy in the region of the IHC and greater epithelial ridge, a loss of OHCs from cochlear apex, and vacuolization of OHCs. Immunofluorescence revealed exuberant overgrowth of auditory afferent neurites in the region of the IHCs and proliferation of auditory efferent neurites in the region of the tunnel of Corti. IHC recordings from these KO mice showed normal I-V curves and responses to applied acetylcholine. Together, these results suggest that prosaposin helps maintain normal innervation patterns to the organ of Corti. Furthermore, prosaposin's overlapping developmental expression pattern and binding capacity toward the nAChR alpha 10 suggest that alpha 10 may also play a role in this function.