Spag6基因在听觉功能障碍中的作用及机制

Deafness represents one of the most common sensory or functional defective diseases, in which more than 60% of patients with deafness are attributed to genetic maladies. Numerous causative genes for this disorder, however, have not been identified to date. Thus, the discovery of a new pathogenic gene for a non-syndromic hearing loss and, more importantly, the elucidation of its mechanism (s) responsible for auditory dysfunction as well as reconstruction are becoming the hot spot of researches in the area of otology. Sperm associated antigen 6 (spag6) gene encodes sperm-associated antigen 6, a cilia-related protein, and the deletion of spag6 gene results in a variety of diseases. Previously, we found, for the first time, that spag6 expressed in the inner ear of wide type mice and spag6 knock out mice appeared severe hearing loss in comparison to normal subjects. The precise mechanism by which spag6 gene elicits auditory dysfunction has not been deciphered to date. Therefore, the present study was designed to: 1) test the effect of spag6 gene on auditory function utilizing spag6 knockout mice; 2) investigate the role of spag6 gene in plannar cell polarity pathway; 3) determine the relationship between spag6 and prestin; 4) analyze the impact of spag6 gene on the development of auditory center; and 5) make a genetic epidemiological survey among patients with deafness. The implementation of this project will unmask the mechanism underlying the action of spag6 gene on deafness and, in turn, offer a new theoretic framework for auditory reconstruction and, finally, may lend a novel therapeutic target for hearing loss.

耳聋是人类发病率最高的感官或功能缺陷性疾病，60%以上的耳聋与遗传有关。目前仍有众多耳聋基因未被鉴定，因此确定新的耳聋基因、揭示其致聋机制有十分重大意义。精子相关抗原6（sperm associated antigen 6，spag6）基因编码纤毛相关蛋白SPAG6，spag6的缺失导致多种疾病。我们前期研究发现，spag6在正常小鼠的内耳表达，spag6基因敲除小鼠出现重度耳聋, 但spag6导致听觉障碍的机制未见报道。本项目在前期工作的基础上，拟采用spag6基因敲除小鼠检测spag6对听功能的影响；进一步探讨spag6在平面细胞极性中的作用，检测spag6与马达蛋白的关系，分析spag6对听觉中枢发育的影响；并开展耳聋患者流行病学调查，藉此阐明spag6与听觉功能异常的关系。本项目的实施将进一步揭示听觉障碍的发生机制，为听觉功能重建提供新的理论依据和治疗靶点

项目背景：耳聋是人类发病率最高的感官或功能缺陷性疾病，但致聋原因非常复杂，其中60％以上的耳聋是由于遗传因素所致，发现新的聋病基因、揭示其致聋机制， 对于治疗和预防听觉功能障碍有十分重要的意义。 我们通过前期研究发现spag6 对鞭毛的结构维持和正常运动具有重要作用，同时在听觉系统的纤毛表达，spag6敲除小鼠出现重度听力损失，但是其致聋机制并不清楚。. 实验目的和研究内容：以spag6敲除小鼠为模型，探索spag6致聋机制。内容为检测spag6对听觉通路上主要结构的影响，包括内耳螺旋神经节（SGN）、毛细胞、中耳纤毛等结构。1）观察spag6纯合小鼠SGN在体内和体外的发育情况。2）探索spag6与prestin蛋白的关系。3）spag6在中耳纤毛的情况，对中耳纤毛功能的影响。. 重要结果和关键数据：1）体内实验发现spag6在小鼠SGN表达，纯合SGN出现过早凋亡，其相关凋亡因子表达上升，电镜显示亚显微结构异常。体外实验发现spag6纯合小鼠SGN均表现出神经突发育异常，纯合小鼠突触蛋白密度明显低于野生型小鼠，表明神经元功能受到影响。2）Spag6纯合小鼠中prestin表达显著降低。3）SPAG6蛋白在中耳腔纤毛表达，spag6缺失导致纤毛极性异常，纯合小鼠出现中耳炎。. 科学意义：初步探索了spag6对听觉通路的影响。数据表明1）Spag6在SGN的发展和功能中起着至关重要的作用2）SPAG6通过维持prestin的正常表达，对OHCs的稳定性是必不可少的，这意味着SPAG6基因对OHCs的机械感觉功能是必不可少的。3）Spag6在小鼠OM发病机制中发挥作用，可能是通过中耳和耳咽管中依赖于平面极性调节纤毛极性

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